61 files changed, 907 insertions, 1268 deletions

diff --git a/sw/programmer/linux/src/flash.c b/sw/programmer/linux/src/flash.c
index 6fcd09f..24d5269 100644
--- a/sw/programmer/linux/src/flash.c
+++ b/sw/programmer/linux/src/flash.c
@@ -32,7 +32,7 @@ int flash_write(const char *romfile, void (*log)(const char *))
             log("[!] Error while reading from file\n");
             break;
         }
-                
+
 		head.addr = (uint16_t) lseek(romfd, 0, SEEK_CUR);
 
 		written = write(flash_serial_fd, &head, sizeof(struct flash_blk));
diff --git a/sw/z80/TODO.txt b/sw/z80/TODO.txt
new file mode 100644
index 0000000..67be671
--- /dev/null
+++ b/sw/z80/TODO.txt
@@ -0,0 +1 @@
+- fix kernel makefile (currently broken)
diff --git a/sw/z80_tests/usart/devices.h b/sw/z80/arch/addresses.h
index a846f9b..07ab473 100644
--- a/sw/z80_tests/usart/devices.h
+++ b/sw/z80/arch/addresses.h
@@ -1,5 +1,5 @@
-#ifndef __DEVICES_H__
-#define __DEVICES_H__
+#ifndef __ADDRESSES_H__
+#define __ADDRESSES_H__
 
 #define ADDR_DEV_ROM_L      0x0000
 #define ADDR_DEV_ROM_H      0x2000
diff --git a/sw/z80/coding_rules.txt b/sw/z80/coding_rules.txt
deleted file mode 100644
index e5c11f0..0000000
--- a/sw/z80/coding_rules.txt
+++ /dev/null
@@ -1,120 +0,0 @@
-CODING STYLE FOR THIS PROJECT
-=============================
-
-In order to have a consistent codebase, there are the following rules on
-writing code in C (and assembly). For the most part they are similar to the
-Linux kernel coding rules by Torvalds.
-
-PROGRAM LOGIC
--------------
-I expect a certain level of common sense from people so I won't mention the
-super-basic stuff. But I would like to point out a few thing I WON'T accept
-(unless there is a valid reason and an explanation of why).  First, I believe
-that code has to be aesthetically pleasing to watch and with a clear logic
-flow so:
-
-    - Avoid deeply nested code and recursive black magic
-
-    - No special cases: generally the code of a function should behave the
-      same with any argument. Avoid horrible exceptions for magic values
-
-    - No extreme modularization: do not write code that is extremely
-      encapsulated with dozens of helper functions to control every signal
-      that runs through the damn motherboard
-
-EDITOR (SPACES > TABS)
-----------------------
-You can use your favourite editor but spaces are better than tabs, no
-discussion. For this project every source file must have an indent of 4
-spaces. Since 80 characters is the standard terminal width, the code has to be
-hard wrapped at 80, 78 or 72 characters. Also there shouldn't be any markup on
-the source code for your editor, not even in the comments; just the code.
-
-    - use spaces, 1 indent - 4 spaces
-    - hard wrap at 80 / 78 / 72 characters
-    - no markup for folds or any other editor specific feature
-    
-
-C CODE INDENT AND BRACES
-------------------------
-I personally prefer the K&R coding style because it was used in 'The C
-Programming Language' book from Dennis Ritchie which is the 'standard' for
-learning C. But I also like Linus' kernel coding rules, so sometimes I might
-use some of his rules. Anyway, you can look them up if you want to or just
-look at the following example that sums most of the important stuff.
-
-    - K&R braces and function prototypes
-    - snake_case for variables and function names
-    - pointer asterisk in front of the variable ( ex: int *p; )
-
-Here's a short example that uses most of the stuff:
-
-    #include <stdio.h>
-    #include <stdlib.h>
-    
-    #define MY_DEVICE_MEMORY_ADDR   0x5020
-
-    #define MY_DEVICE_FLAG_RDY      1
-    #define MY_DEVICE_FLAG_ERR      2
-
-    // same for unions
-    struct my_device
-    {
-        volatile uint8_t buffer;
-        volatile uint8_t flags;
-    } *_my_dev = (struct my_device *) MY_DEVICE_MEMORY_ADDR;
-
-    
-    int my_device_write(uint8_t *data, size_t size);
-
-    /* This is the main function
-     * and this is a multiline comment to explain something if needed
-     */
-    int main(int argc, char *argv[])
-    {
-        int i;
-        int j = 0;
-        uint8_t data[2] = { 0xFF, 0xAB };
-        const char *string = "My magic string";
-
-        while (j < 100) {
-            j++;
-        }
-
-        printf("%s\n", string);
-
-        if (some_condition) {
-            // inline comment
-        } else {
-            my_device_write(data, 2);
-        }
-
-        switch (i) {
-        case 0:
-            some_function();
-            break;
-
-        case 1:
-            // ...
-            break;
-
-        default:
-            // ...
-        }
-    }
-
-    int my_device_write(uint8_t *data, size_t size) 
-    {
-        int i;
-
-        for (i = 0; i < size; i++) {
-            _my_dev.buffer = data;
-            while (!(_my_dev.flags & (1<<MY_DEVICE_FLAG_RDY)));
-
-            if (_my_dev.flags &  (1<<MY_DEVICE_FLAG_ERR)) {
-                return -1;
-            }
-        }
-
-        return i;
-    }
diff --git a/sw/z80/crt0.rel b/sw/z80/crt0.rel
deleted file mode 100644
index 880fd57..0000000
--- a/sw/z80/crt0.rel
+++ /dev/null
@@ -1,86 +0,0 @@
-XL2
-H 14 areas 5 global symbols
-M crt0
-S .__.ABS. Def0000
-S _kmain Ref0000
-A _CODE size A flags 0 addr 0
-S __clock Def0000
-S _exit Def0004
-A _HEADER size 0 flags 8 addr 0
-A _HEADER0 size 3 flags 8 addr 0
-A _HEADER1 size 2 flags 8 addr 8
-A _HEADER2 size 2 flags 8 addr 10
-A _HEADER3 size 2 flags 8 addr 18
-A _HEADER4 size 2 flags 8 addr 20
-A _HEADER5 size 2 flags 8 addr 28
-A _HEADER6 size 2 flags 8 addr 30
-A _HEADER7 size 2 flags 8 addr 38
-A _HEADER8 size C flags 8 addr 100
-A _HOME size 0 flags 0 addr 0
-A _INITIALIZER size 0 flags 0 addr 0
-A _GSINIT size 6 flags 0 addr 0
-S gsinit Def0000
-A _GSFINAL size 1 flags 0 addr 0
-A _DATA size 0 flags 0 addr 0
-A _INITIALIZED size 0 flags 0 addr 0
-A _BSEG size 0 flags 0 addr 0
-A _BSS size 0 flags 0 addr 0
-A _HEAP size 0 flags 0 addr 0
-T 00 00
-R 00 00 02 00
-T 00 00 C3 00 01
-R 00 00 02 00 00 03 0A 00
-T 08 00
-R 00 00 03 00
-T 08 00 ED 4D
-R 00 00 03 00
-T 10 00
-R 00 00 04 00
-T 10 00 ED 4D
-R 00 00 04 00
-T 18 00
-R 00 00 05 00
-T 18 00 ED 4D
-R 00 00 05 00
-T 20 00
-R 00 00 06 00
-T 20 00 ED 4D
-R 00 00 06 00
-T 28 00
-R 00 00 07 00
-T 28 00 ED 4D
-R 00 00 07 00
-T 30 00
-R 00 00 08 00
-T 30 00 ED 4D
-R 00 00 08 00
-T 38 00
-R 00 00 09 00
-T 38 00 ED 4D
-R 00 00 09 00
-T 00 01
-R 00 00 0A 00
-T 00 01
-R 00 00 0A 00
-T 00 01 31 FF FF CD 00 00 CD 00 00 C3 04 00
-R 00 00 0A 00 00 06 0D 00 02 09 01 00 00 0C 00 00
-T 00 00
-R 00 00 00 00
-T 00 00 3E 02 CF C9
-R 00 00 00 00
-T 04 00
-R 00 00 00 00
-T 04 00 3E 00 CF
-R 00 00 00 00
-T 07 00
-R 00 00 00 00
-T 07 00 76 18 FD
-R 00 00 00 00
-T 00 00
-R 00 00 0D 00
-T 00 00 78 B1 28 02 ED B0
-R 00 00 0D 00
-T 06 00
-R 00 00 0D 00
-T 00 00 C9
-R 00 00 0E 00
diff --git a/sw/z80_tests/usart/build/ctc.asm b/sw/z80/drivers/build/ctc.asm
index 838756a..838756a 100644
--- a/sw/z80_tests/usart/build/ctc.asm
+++ b/sw/z80/drivers/build/ctc.asm
diff --git a/sw/z80_tests/usart/build/ctc.lst b/sw/z80/drivers/build/ctc.lst
index e758d8a..e758d8a 100644
--- a/sw/z80_tests/usart/build/ctc.lst
+++ b/sw/z80/drivers/build/ctc.lst
diff --git a/sw/z80_tests/usart/build/ctc.rel b/sw/z80/drivers/build/ctc.rel
index 50a8b42..50a8b42 100644
--- a/sw/z80_tests/usart/build/ctc.rel
+++ b/sw/z80/drivers/build/ctc.rel
diff --git a/sw/z80_tests/usart/build/ctc.sym b/sw/z80/drivers/build/ctc.sym
index 82ca00e..82ca00e 100644
--- a/sw/z80_tests/usart/build/ctc.sym
+++ b/sw/z80/drivers/build/ctc.sym
diff --git a/sw/z80_tests/usart/build/pio.asm b/sw/z80/drivers/build/pio.asm
index ee1fcc6..3045492 100644
--- a/sw/z80_tests/usart/build/pio.asm
+++ b/sw/z80/drivers/build/pio.asm
@@ -13,6 +13,8 @@
 	.globl _pio_set_mode
 	.globl _pio_set_interrupts
 	.globl _pio_set_interrupts_mask
+	.globl _pio_read
+	.globl _pio_write
 ;--------------------------------------------------------
 ; special function registers
 ;--------------------------------------------------------
@@ -185,6 +187,44 @@ _pio_set_interrupts_mask::
 	ld	(hl),c
 ;pio.c:39: _pio_control(port, mask);
 	ret
+;pio.c:42: uint8_t pio_read(int port)
+;	---------------------------------
+; Function pio_read
+; ---------------------------------
+_pio_read::
+;pio.c:44: return *(pio_port + port);
+	ld	hl,#2
+	add	hl,sp
+	ld	iy,#_pio_port
+	ld	a,0 (iy)
+	add	a, (hl)
+	ld	c,a
+	ld	a,1 (iy)
+	inc	hl
+	adc	a, (hl)
+	ld	b,a
+	ld	a,(bc)
+	ld	l,a
+	ret
+;pio.c:47: void pio_write(int port, uint8_t data)
+;	---------------------------------
+; Function pio_write
+; ---------------------------------
+_pio_write::
+;pio.c:49: _pio_data(port, data);
+	ld	hl, #4+0
+	add	hl, sp
+	ld	c, (hl)
+	pop	de
+	pop	hl
+	push	hl
+	push	de
+;pio.c:8: *(pio_port + port) = data;
+	ld	de,(_pio_port)
+	add	hl,de
+	ld	(hl),c
+;pio.c:49: _pio_data(port, data);
+	ret
 	.area _CODE
 	.area _INITIALIZER
 __xinit__pio_port:
diff --git a/sw/z80/drivers/build/pio.lst b/sw/z80/drivers/build/pio.lst
new file mode 100644
index 0000000..0b83616
--- /dev/null
+++ b/sw/z80/drivers/build/pio.lst
@@ -0,0 +1,234 @@
+                              1 ;--------------------------------------------------------
+                              2 ; File Created by SDCC : free open source ANSI-C Compiler
+                              3 ; Version 3.6.0 #9615 (Linux)
+                              4 ;--------------------------------------------------------
+                              5 	.module pio
+                              6 	.optsdcc -mz80
+                              7 	
+                              8 ;--------------------------------------------------------
+                              9 ; Public variables in this module
+                             10 ;--------------------------------------------------------
+                             11 	.globl __pio_data
+                             12 	.globl __pio_control
+                             13 	.globl _pio_set_mode
+                             14 	.globl _pio_set_interrupts
+                             15 	.globl _pio_set_interrupts_mask
+                             16 	.globl _pio_read
+                             17 	.globl _pio_write
+                             18 ;--------------------------------------------------------
+                             19 ; special function registers
+                             20 ;--------------------------------------------------------
+                             21 ;--------------------------------------------------------
+                             22 ; ram data
+                             23 ;--------------------------------------------------------
+                             24 	.area _DATA
+                             25 ;--------------------------------------------------------
+                             26 ; ram data
+                             27 ;--------------------------------------------------------
+                             28 	.area _INITIALIZED
+   0000                      29 _pio_port:
+   0000                      30 	.ds 2
+   0002                      31 _pio_ctrl:
+   0002                      32 	.ds 2
+                             33 ;--------------------------------------------------------
+                             34 ; absolute external ram data
+                             35 ;--------------------------------------------------------
+                             36 	.area _DABS (ABS)
+                             37 ;--------------------------------------------------------
+                             38 ; global & static initialisations
+                             39 ;--------------------------------------------------------
+                             40 	.area _HOME
+                             41 	.area _GSINIT
+                             42 	.area _GSFINAL
+                             43 	.area _GSINIT
+                             44 ;--------------------------------------------------------
+                             45 ; Home
+                             46 ;--------------------------------------------------------
+                             47 	.area _HOME
+                             48 	.area _HOME
+                             49 ;--------------------------------------------------------
+                             50 ; code
+                             51 ;--------------------------------------------------------
+                             52 	.area _CODE
+                             53 ;pio.c:6: inline void _pio_data(int port, uint8_t data)
+                             54 ;	---------------------------------
+                             55 ; Function _pio_data
+                             56 ; ---------------------------------
+   0000                      57 __pio_data::
+                             58 ;pio.c:8: *(pio_port + port) = data;
+   0000 21 02 00      [10]   59 	ld	hl,#2
+   0003 39            [11]   60 	add	hl,sp
+   0004 FD 21r00r00   [14]   61 	ld	iy,#_pio_port
+   0008 FD 7E 00      [19]   62 	ld	a,0 (iy)
+   000B 86            [ 7]   63 	add	a, (hl)
+   000C 4F            [ 4]   64 	ld	c,a
+   000D FD 7E 01      [19]   65 	ld	a,1 (iy)
+   0010 23            [ 6]   66 	inc	hl
+   0011 8E            [ 7]   67 	adc	a, (hl)
+   0012 47            [ 4]   68 	ld	b,a
+   0013 21 04 00      [10]   69 	ld	hl, #4+0
+   0016 39            [11]   70 	add	hl, sp
+   0017 7E            [ 7]   71 	ld	a, (hl)
+   0018 02            [ 7]   72 	ld	(bc),a
+   0019 C9            [10]   73 	ret
+                             74 ;pio.c:11: inline void _pio_control(int port, uint8_t cmd)
+                             75 ;	---------------------------------
+                             76 ; Function _pio_control
+                             77 ; ---------------------------------
+   001A                      78 __pio_control::
+                             79 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   001A 21 02 00      [10]   80 	ld	hl,#2
+   001D 39            [11]   81 	add	hl,sp
+   001E FD 21r02r00   [14]   82 	ld	iy,#_pio_ctrl
+   0022 FD 7E 00      [19]   83 	ld	a,0 (iy)
+   0025 86            [ 7]   84 	add	a, (hl)
+   0026 4F            [ 4]   85 	ld	c,a
+   0027 FD 7E 01      [19]   86 	ld	a,1 (iy)
+   002A 23            [ 6]   87 	inc	hl
+   002B 8E            [ 7]   88 	adc	a, (hl)
+   002C 47            [ 4]   89 	ld	b,a
+   002D 21 04 00      [10]   90 	ld	hl, #4+0
+   0030 39            [11]   91 	add	hl, sp
+   0031 7E            [ 7]   92 	ld	a, (hl)
+   0032 02            [ 7]   93 	ld	(bc),a
+   0033 C9            [10]   94 	ret
+                             95 ;pio.c:16: void pio_set_mode(int port, int mode, uint8_t io)
+                             96 ;	---------------------------------
+                             97 ; Function pio_set_mode
+                             98 ; ---------------------------------
+   0034                      99 _pio_set_mode::
+                            100 ;pio.c:19: _pio_control(port, ((mode << 6) | 0x0F));
+   0034 21 04 00      [10]  101 	ld	hl, #4+0
+   0037 39            [11]  102 	add	hl, sp
+   0038 7E            [ 7]  103 	ld	a, (hl)
+   0039 0F            [ 4]  104 	rrca
+   003A 0F            [ 4]  105 	rrca
+   003B E6 C0         [ 7]  106 	and	a,#0xc0
+   003D F6 0F         [ 7]  107 	or	a, #0x0f
+   003F 4F            [ 4]  108 	ld	c,a
+   0040 D1            [10]  109 	pop	de
+   0041 E1            [10]  110 	pop	hl
+   0042 E5            [11]  111 	push	hl
+   0043 D5            [11]  112 	push	de
+                            113 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   0044 FD 2Ar02r00   [20]  114 	ld	iy,(_pio_ctrl)
+   0048 5D            [ 4]  115 	ld	e, l
+   0049 54            [ 4]  116 	ld	d, h
+   004A FD 19         [15]  117 	add	iy, de
+   004C FD 71 00      [19]  118 	ld	0 (iy), c
+                            119 ;pio.c:23: if (mode == PIO_MODE_BIT_IO) {
+   004F FD 21 04 00   [14]  120 	ld	iy,#4
+   0053 FD 39         [15]  121 	add	iy,sp
+   0055 FD 7E 00      [19]  122 	ld	a,0 (iy)
+   0058 D6 03         [ 7]  123 	sub	a, #0x03
+   005A C0            [11]  124 	ret	NZ
+   005B FD 7E 01      [19]  125 	ld	a,1 (iy)
+   005E B7            [ 4]  126 	or	a, a
+   005F C0            [11]  127 	ret	NZ
+                            128 ;pio.c:24: _pio_control(port, io);
+   0060 FD 21 06 00   [14]  129 	ld	iy,#6
+   0064 FD 39         [15]  130 	add	iy,sp
+   0066 FD 4E 00      [19]  131 	ld	c,0 (iy)
+                            132 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   0069 ED 5Br02r00   [20]  133 	ld	de,(_pio_ctrl)
+   006D 19            [11]  134 	add	hl,de
+   006E 71            [ 7]  135 	ld	(hl),c
+                            136 ;pio.c:24: _pio_control(port, io);
+   006F C9            [10]  137 	ret
+                            138 ;pio.c:28: void pio_set_interrupts(int port, int control)
+                            139 ;	---------------------------------
+                            140 ; Function pio_set_interrupts
+                            141 ; ---------------------------------
+   0070                     142 _pio_set_interrupts::
+                            143 ;pio.c:31: _pio_control(port, (control | 0x07));
+   0070 21 04 00      [10]  144 	ld	hl, #4+0
+   0073 39            [11]  145 	add	hl, sp
+   0074 7E            [ 7]  146 	ld	a, (hl)
+   0075 F6 07         [ 7]  147 	or	a, #0x07
+   0077 4F            [ 4]  148 	ld	c,a
+   0078 D1            [10]  149 	pop	de
+   0079 E1            [10]  150 	pop	hl
+   007A E5            [11]  151 	push	hl
+   007B D5            [11]  152 	push	de
+                            153 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   007C ED 5Br02r00   [20]  154 	ld	de,(_pio_ctrl)
+   0080 19            [11]  155 	add	hl,de
+   0081 71            [ 7]  156 	ld	(hl),c
+                            157 ;pio.c:31: _pio_control(port, (control | 0x07));
+   0082 C9            [10]  158 	ret
+                            159 ;pio.c:34: void pio_set_interrupts_mask(int port, int control, uint8_t mask)
+                            160 ;	---------------------------------
+                            161 ; Function pio_set_interrupts_mask
+                            162 ; ---------------------------------
+   0083                     163 _pio_set_interrupts_mask::
+                            164 ;pio.c:38: _pio_control(port, (control | 0x17));
+   0083 21 04 00      [10]  165 	ld	hl, #4+0
+   0086 39            [11]  166 	add	hl, sp
+   0087 7E            [ 7]  167 	ld	a, (hl)
+   0088 F6 17         [ 7]  168 	or	a, #0x17
+   008A 4F            [ 4]  169 	ld	c,a
+   008B D1            [10]  170 	pop	de
+   008C E1            [10]  171 	pop	hl
+   008D E5            [11]  172 	push	hl
+   008E D5            [11]  173 	push	de
+                            174 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   008F FD 2Ar02r00   [20]  175 	ld	iy,(_pio_ctrl)
+   0093 5D            [ 4]  176 	ld	e, l
+   0094 54            [ 4]  177 	ld	d, h
+   0095 FD 19         [15]  178 	add	iy, de
+   0097 FD 71 00      [19]  179 	ld	0 (iy), c
+                            180 ;pio.c:39: _pio_control(port, mask);
+   009A FD 21 06 00   [14]  181 	ld	iy,#6
+   009E FD 39         [15]  182 	add	iy,sp
+   00A0 FD 4E 00      [19]  183 	ld	c,0 (iy)
+                            184 ;pio.c:13: *(pio_ctrl + port) = cmd;
+   00A3 ED 5Br02r00   [20]  185 	ld	de,(_pio_ctrl)
+   00A7 19            [11]  186 	add	hl,de
+   00A8 71            [ 7]  187 	ld	(hl),c
+                            188 ;pio.c:39: _pio_control(port, mask);
+   00A9 C9            [10]  189 	ret
+                            190 ;pio.c:42: uint8_t pio_read(int port)
+                            191 ;	---------------------------------
+                            192 ; Function pio_read
+                            193 ; ---------------------------------
+   00AA                     194 _pio_read::
+                            195 ;pio.c:44: return *(pio_port + port);
+   00AA 21 02 00      [10]  196 	ld	hl,#2
+   00AD 39            [11]  197 	add	hl,sp
+   00AE FD 21r00r00   [14]  198 	ld	iy,#_pio_port
+   00B2 FD 7E 00      [19]  199 	ld	a,0 (iy)
+   00B5 86            [ 7]  200 	add	a, (hl)
+   00B6 4F            [ 4]  201 	ld	c,a
+   00B7 FD 7E 01      [19]  202 	ld	a,1 (iy)
+   00BA 23            [ 6]  203 	inc	hl
+   00BB 8E            [ 7]  204 	adc	a, (hl)
+   00BC 47            [ 4]  205 	ld	b,a
+   00BD 0A            [ 7]  206 	ld	a,(bc)
+   00BE 6F            [ 4]  207 	ld	l,a
+   00BF C9            [10]  208 	ret
+                            209 ;pio.c:47: void pio_write(int port, uint8_t data)
+                            210 ;	---------------------------------
+                            211 ; Function pio_write
+                            212 ; ---------------------------------
+   00C0                     213 _pio_write::
+                            214 ;pio.c:49: _pio_data(port, data);
+   00C0 21 04 00      [10]  215 	ld	hl, #4+0
+   00C3 39            [11]  216 	add	hl, sp
+   00C4 4E            [ 7]  217 	ld	c, (hl)
+   00C5 D1            [10]  218 	pop	de
+   00C6 E1            [10]  219 	pop	hl
+   00C7 E5            [11]  220 	push	hl
+   00C8 D5            [11]  221 	push	de
+                            222 ;pio.c:8: *(pio_port + port) = data;
+   00C9 ED 5Br00r00   [20]  223 	ld	de,(_pio_port)
+   00CD 19            [11]  224 	add	hl,de
+   00CE 71            [ 7]  225 	ld	(hl),c
+                            226 ;pio.c:49: _pio_data(port, data);
+   00CF C9            [10]  227 	ret
+                            228 	.area _CODE
+                            229 	.area _INITIALIZER
+   0000                     230 __xinit__pio_port:
+   0000 00 42               231 	.dw #0x4200
+   0002                     232 __xinit__pio_ctrl:
+   0002 02 42               233 	.dw #0x4202
+                            234 	.area _CABS (ABS)
diff --git a/sw/z80_tests/usart/build/pio.rel b/sw/z80/drivers/build/pio.rel
index 90210a9..d9b1ac3 100644
--- a/sw/z80_tests/usart/build/pio.rel
+++ b/sw/z80/drivers/build/pio.rel
@@ -1,13 +1,15 @@
 XL2
-H 9 areas 6 global symbols
+H 9 areas 8 global symbols
 M pio
 O -mz80
 S .__.ABS. Def0000
-A _CODE size AA flags 0 addr 0
+A _CODE size D0 flags 0 addr 0
 S _pio_set_interrupts Def0070
 S _pio_set_mode Def0034
 S _pio_set_interrupts_mask Def0083
+S _pio_read Def00AA
 S __pio_control Def001A
+S _pio_write Def00C0
 S __pio_data Def0000
 A _DATA size 0 flags 0 addr 0
 A _INITIALIZED size 4 flags 0 addr 0
@@ -63,6 +65,18 @@ T 91 00 02 00 5D 54 FD 19 FD 71 00 FD 21 06 00 FD
 R 00 00 00 00 00 02 02 00
 T 9F 00 39 FD 4E 00 ED 5B 02 00 19 71 C9
 R 00 00 00 00 00 08 02 00
+T AA 00
+R 00 00 00 00
+T AA 00 21 02 00 39 FD 21 00 00 FD 7E 00 86 4F FD
+R 00 00 00 00 00 08 02 00
+T B8 00 7E 01 23 8E 47 0A 6F C9
+R 00 00 00 00
+T C0 00
+R 00 00 00 00
+T C0 00 21 04 00 39 4E D1 E1 E5 D5 ED 5B 00 00 19
+R 00 00 00 00 00 0D 02 00
+T CE 00 71 C9
+R 00 00 00 00
 T 00 00
 R 00 00 07 00
 T 00 00 00 42
diff --git a/sw/z80_tests/usart/build/pio.sym b/sw/z80/drivers/build/pio.sym
index 3cf582f..52f787c 100644
--- a/sw/z80_tests/usart/build/pio.sym
+++ b/sw/z80/drivers/build/pio.sym
@@ -13,17 +13,18 @@ Symbol Table
   7 __xinit__pio_port                                              0000 R
   2 _pio_ctrl                                                      0002 R
   2 _pio_port                                                      0000 R
+  0 _pio_read                                                      00AA GR
   0 _pio_set_interrupts                                            0070 GR
   0 _pio_set_interrupts_mask                                       0083 GR
   0 _pio_set_mode                                                  0034 GR
-
+  0 _pio_write                                                     00C0 GR
 
 ASxxxx Assembler V02.00 + NoICE + SDCC mods  (Zilog Z80 / Hitachi HD64180), page 2.
 Hexadecimal [16-Bits]
 
 Area Table
 
-   0 _CODE                                      size   AA   flags    0
+   0 _CODE                                      size   D0   flags    0
    1 _DATA                                      size    0   flags    0
    2 _INITIALIZED                               size    4   flags    0
    3 _DABS                                      size    0   flags    8
diff --git a/sw/z80_tests/usart/build/usart.asm b/sw/z80/drivers/build/usart.asm
index 58d6fdf..fb65d62 100644
--- a/sw/z80_tests/usart/build/usart.asm
+++ b/sw/z80/drivers/build/usart.asm
@@ -366,14 +366,14 @@ _usart_read::
 	ld	sp,hl
 ;usart.c:77: uint8_t *bp = buffer;
 	ld	a,4 (ix)
-	ld	-6 (ix),a
+	ld	-4 (ix),a
 	ld	a,5 (ix)
-	ld	-5 (ix),a
+	ld	-3 (ix),a
 ;usart.c:80: while (count--) {
 	ld	c,6 (ix)
 	ld	b,7 (ix)
-	ld	-4 (ix),#0x00
-	ld	-3 (ix),#0x00
+	ld	hl,#0x0000
+	ex	(sp), hl
 00105$:
 	ld	e, c
 	ld	d, b
@@ -384,12 +384,12 @@ _usart_read::
 ;usart.c:81: *(bp++) = _usart->buffer;
 	ld	hl,(__usart)
 	ld	e,(hl)
-	pop	hl
-	push	hl
+	ld	l,-4 (ix)
+	ld	h,-3 (ix)
 	ld	(hl),e
-	inc	-6 (ix)
+	inc	-4 (ix)
 	jr	NZ,00123$
-	inc	-5 (ix)
+	inc	-3 (ix)
 00123$:
 	ld	de,(__usart)
 ;usart.c:83: if (_usart->LSR.framing_error || _usart->LSR.parity_error) {
@@ -414,23 +414,22 @@ _usart_read::
 	jr	Z,00102$
 00101$:
 ;usart.c:84: bp--; // delete last byte (?)
-	pop	hl
-	push	hl
+	ld	l,-4 (ix)
+	ld	h,-3 (ix)
 	dec	hl
-	ex	(sp), hl
+	ld	-4 (ix),l
+	ld	-3 (ix),h
 	jr	00105$
 00102$:
 ;usart.c:86: read_count++;
-	inc	-4 (ix)
+	inc	-6 (ix)
 	jr	NZ,00105$
-	inc	-3 (ix)
+	inc	-5 (ix)
 	jr	00105$
 00107$:
 ;usart.c:90: return read_count;
-	pop	bc
 	pop	hl
 	push	hl
-	push	bc
 	ld	sp, ix
 	pop	ix
 	ret
diff --git a/sw/z80_tests/usart/build/usart.lst b/sw/z80/drivers/build/usart.lst
index 7706cff..65365fe 100644
--- a/sw/z80_tests/usart/build/usart.lst
+++ b/sw/z80/drivers/build/usart.lst
@@ -366,30 +366,30 @@
    01A4 F9            [ 6]  366 	ld	sp,hl
                             367 ;usart.c:77: uint8_t *bp = buffer;
    01A5 DD 7E 04      [19]  368 	ld	a,4 (ix)
-   01A8 DD 77 FA      [19]  369 	ld	-6 (ix),a
+   01A8 DD 77 FC      [19]  369 	ld	-4 (ix),a
    01AB DD 7E 05      [19]  370 	ld	a,5 (ix)
-   01AE DD 77 FB      [19]  371 	ld	-5 (ix),a
+   01AE DD 77 FD      [19]  371 	ld	-3 (ix),a
                             372 ;usart.c:80: while (count--) {
    01B1 DD 4E 06      [19]  373 	ld	c,6 (ix)
    01B4 DD 46 07      [19]  374 	ld	b,7 (ix)
-   01B7 DD 36 FC 00   [19]  375 	ld	-4 (ix),#0x00
-   01BB DD 36 FD 00   [19]  376 	ld	-3 (ix),#0x00
-   01BF                     377 00105$:
-   01BF 59            [ 4]  378 	ld	e, c
-   01C0 50            [ 4]  379 	ld	d, b
-   01C1 0B            [ 6]  380 	dec	bc
-   01C2 7A            [ 4]  381 	ld	a,d
-   01C3 B3            [ 4]  382 	or	a,e
-   01C4 28 48         [12]  383 	jr	Z,00107$
+   01B7 21 00 00      [10]  375 	ld	hl,#0x0000
+   01BA E3            [19]  376 	ex	(sp), hl
+   01BB                     377 00105$:
+   01BB 59            [ 4]  378 	ld	e, c
+   01BC 50            [ 4]  379 	ld	d, b
+   01BD 0B            [ 6]  380 	dec	bc
+   01BE 7A            [ 4]  381 	ld	a,d
+   01BF B3            [ 4]  382 	or	a,e
+   01C0 28 55         [12]  383 	jr	Z,00107$
                             384 ;usart.c:81: *(bp++) = _usart->buffer;
-   01C6 2Ar00r00      [16]  385 	ld	hl,(__usart)
-   01C9 5E            [ 7]  386 	ld	e,(hl)
-   01CA E1            [10]  387 	pop	hl
-   01CB E5            [11]  388 	push	hl
+   01C2 2Ar00r00      [16]  385 	ld	hl,(__usart)
+   01C5 5E            [ 7]  386 	ld	e,(hl)
+   01C6 DD 6E FC      [19]  387 	ld	l,-4 (ix)
+   01C9 DD 66 FD      [19]  388 	ld	h,-3 (ix)
    01CC 73            [ 7]  389 	ld	(hl),e
-   01CD DD 34 FA      [23]  390 	inc	-6 (ix)
+   01CD DD 34 FC      [23]  390 	inc	-4 (ix)
    01D0 20 03         [12]  391 	jr	NZ,00123$
-   01D2 DD 34 FB      [23]  392 	inc	-5 (ix)
+   01D2 DD 34 FD      [23]  392 	inc	-3 (ix)
    01D5                     393 00123$:
    01D5 ED 5Br00r00   [20]  394 	ld	de,(__usart)
                             395 ;usart.c:83: if (_usart->LSR.framing_error || _usart->LSR.parity_error) {
@@ -411,31 +411,30 @@
    01F8 0F            [ 4]  411 	rrca
    01F9 0F            [ 4]  412 	rrca
    01FA E6 01         [ 7]  413 	and	a,#0x01
-   01FC 28 06         [12]  414 	jr	Z,00102$
+   01FC 28 0F         [12]  414 	jr	Z,00102$
    01FE                     415 00101$:
                             416 ;usart.c:84: bp--; // delete last byte (?)
-   01FE E1            [10]  417 	pop	hl
-   01FF E5            [11]  418 	push	hl
-   0200 2B            [ 6]  419 	dec	hl
-   0201 E3            [19]  420 	ex	(sp), hl
-   0202 18 BB         [12]  421 	jr	00105$
-   0204                     422 00102$:
-                            423 ;usart.c:86: read_count++;
-   0204 DD 34 FC      [23]  424 	inc	-4 (ix)
-   0207 20 B6         [12]  425 	jr	NZ,00105$
-   0209 DD 34 FD      [23]  426 	inc	-3 (ix)
-   020C 18 B1         [12]  427 	jr	00105$
-   020E                     428 00107$:
-                            429 ;usart.c:90: return read_count;
-   020E C1            [10]  430 	pop	bc
-   020F E1            [10]  431 	pop	hl
-   0210 E5            [11]  432 	push	hl
-   0211 C5            [11]  433 	push	bc
-   0212 DD F9         [10]  434 	ld	sp, ix
-   0214 DD E1         [14]  435 	pop	ix
-   0216 C9            [10]  436 	ret
-                            437 	.area _CODE
-                            438 	.area _INITIALIZER
-   0000                     439 __xinit___usart:
-   0000 00 40               440 	.dw #0x4000
-                            441 	.area _CABS (ABS)
+   01FE DD 6E FC      [19]  417 	ld	l,-4 (ix)
+   0201 DD 66 FD      [19]  418 	ld	h,-3 (ix)
+   0204 2B            [ 6]  419 	dec	hl
+   0205 DD 75 FC      [19]  420 	ld	-4 (ix),l
+   0208 DD 74 FD      [19]  421 	ld	-3 (ix),h
+   020B 18 AE         [12]  422 	jr	00105$
+   020D                     423 00102$:
+                            424 ;usart.c:86: read_count++;
+   020D DD 34 FA      [23]  425 	inc	-6 (ix)
+   0210 20 A9         [12]  426 	jr	NZ,00105$
+   0212 DD 34 FB      [23]  427 	inc	-5 (ix)
+   0215 18 A4         [12]  428 	jr	00105$
+   0217                     429 00107$:
+                            430 ;usart.c:90: return read_count;
+   0217 E1            [10]  431 	pop	hl
+   0218 E5            [11]  432 	push	hl
+   0219 DD F9         [10]  433 	ld	sp, ix
+   021B DD E1         [14]  434 	pop	ix
+   021D C9            [10]  435 	ret
+                            436 	.area _CODE
+                            437 	.area _INITIALIZER
+   0000                     438 __xinit___usart:
+   0000 00 40               439 	.dw #0x4000
+                            440 	.area _CABS (ABS)
diff --git a/sw/z80_tests/usart/build/usart.rel b/sw/z80/drivers/build/usart.rel
index 480c037..29ad600 100644
--- a/sw/z80_tests/usart/build/usart.rel
+++ b/sw/z80/drivers/build/usart.rel
@@ -3,7 +3,7 @@ H 9 areas B global symbols
 M usart
 O -mz80
 S .__.ABS. Def0000
-A _CODE size 217 flags 0 addr 0
+A _CODE size 21E flags 0 addr 0
 S _usart_read Def0198
 S _usart_set_autoflow Def00CE
 S _usart_word_length Def00B5
@@ -146,15 +146,15 @@ T 98 01
 R 00 00 00 00
 T 98 01 DD E5 DD 21 00 00 DD 39 21 FA FF 39 F9 DD
 R 00 00 00 00
-T A6 01 7E 04 DD 77 FA DD 7E 05 DD 77 FB DD 4E 06
+T A6 01 7E 04 DD 77 FC DD 7E 05 DD 77 FD DD 4E 06
 R 00 00 00 00
-T B4 01 DD 46 07 DD 36 FC 00 DD 36 FD 00
+T B4 01 DD 46 07 21 00 00 E3
 R 00 00 00 00
-T BF 01
+T BB 01
 R 00 00 00 00
-T BF 01 59 50 0B 7A B3 28 48 2A 00 00 5E E1 E5 73
+T BB 01 59 50 0B 7A B3 28 55 2A 00 00 5E DD 6E FC
 R 00 00 00 00 00 0A 02 00
-T CD 01 DD 34 FA 20 03 DD 34 FB
+T C9 01 DD 66 FD 73 DD 34 FC 20 03 DD 34 FD
 R 00 00 00 00
 T D5 01
 R 00 00 00 00
@@ -162,19 +162,21 @@ T D5 01 ED 5B 00 00 21 0D 00 19 DD 75 FE DD 74 FF
 R 00 00 00 00 00 04 02 00
 T E3 01 DD 6E FE DD 66 FF 7E 0F 0F 0F E6 01 20 0D
 R 00 00 00 00
-T F1 01 DD 6E FE DD 66 FF 7E 0F 0F E6 01 28 06
+T F1 01 DD 6E FE DD 66 FF 7E 0F 0F E6 01 28 0F
 R 00 00 00 00
 T FE 01
 R 00 00 00 00
-T FE 01 E1 E5 2B E3 18 BB
+T FE 01 DD 6E FC DD 66 FD 2B DD 75 FC DD 74 FD 18
 R 00 00 00 00
-T 04 02
+T 0C 02 AE
 R 00 00 00 00
-T 04 02 DD 34 FC 20 B6 DD 34 FD 18 B1
+T 0D 02
 R 00 00 00 00
-T 0E 02
+T 0D 02 DD 34 FA 20 A9 DD 34 FB 18 A4
 R 00 00 00 00
-T 0E 02 C1 E1 E5 C5 DD F9 DD E1 C9
+T 17 02
+R 00 00 00 00
+T 17 02 E1 E5 DD F9 DD E1 C9
 R 00 00 00 00
 T 00 00
 R 00 00 07 00
diff --git a/sw/z80_tests/usart/build/usart.sym b/sw/z80/drivers/build/usart.sym
index a6e3c38..71004e3 100644
--- a/sw/z80_tests/usart/build/usart.sym
+++ b/sw/z80/drivers/build/usart.sym
@@ -26,7 +26,7 @@ Hexadecimal [16-Bits]
 
 Area Table
 
-   0 _CODE                                      size  217   flags    0
+   0 _CODE                                      size  21E   flags    0
    1 _DATA                                      size    0   flags    0
    2 _INITIALIZED                               size    2   flags    0
    3 _DABS                                      size    0   flags    8
diff --git a/sw/z80/kernel/drivers/ctc.c b/sw/z80/drivers/ctc.c
index 841202a..5ac4254 100644
--- a/sw/z80/kernel/drivers/ctc.c
+++ b/sw/z80/drivers/ctc.c
@@ -1,4 +1,4 @@
-#include "drivers/ctc.h"
+#include "ctc.h"
 
 void ctc_control()
 {
diff --git a/sw/z80/kernel/include/drivers/ctc.h b/sw/z80/drivers/include/ctc.h
index 80e8b4b..80e8b4b 100644
--- a/sw/z80/kernel/include/drivers/ctc.h
+++ b/sw/z80/drivers/include/ctc.h
diff --git a/sw/z80/kernel/include/drivers/pio.h b/sw/z80/drivers/include/pio.h
index 0df2ed0..e91029c 100644
--- a/sw/z80/kernel/include/drivers/pio.h
+++ b/sw/z80/drivers/include/pio.h
@@ -1,8 +1,8 @@
 #ifndef __PIO_H__
 #define __PIO_H__
 
-#include "devices.h"
-#include "types.h"
+#include "addresses.h"
+#include <stdint.h>
 
 #define PIO_A       0
 #define PIO_B       1
@@ -20,6 +20,7 @@
 inline void _pio_data(int port, uint8_t data);
 inline void _pio_control(int port, uint8_t cmd);
 
+/* the last argument is needed only for IO mode */
 void pio_set_mode(int port, int mode, uint8_t io);
 
 void pio_set_interrupts(int port, int control);
@@ -34,4 +35,4 @@ inline void pio_write_pin(int port, uint8_t pin);
 
 // TODO: implement mode (in/out/both) and interrupt vector
 
-#endif // __PIO_H__
+#endif /* __PIO_H__ */
diff --git a/sw/z80/kernel/include/drivers/usart.h b/sw/z80/drivers/include/usart.h
index b85ee3e..bb06aab 100644
--- a/sw/z80/kernel/include/drivers/usart.h
+++ b/sw/z80/drivers/include/usart.h
@@ -1,10 +1,10 @@
 #ifndef __USART_H__
 #define __USART_H__
 
-#include "types.h"
-#include "devices.h"
+#include "addresses.h"
 
-#include "string.h"
+#include <stdint.h>
+#include <string.h>
 
 // baudrate clock divisors 
 // values from TL16C550C datasheet (table 9 for 1.8432 MHz crystal)
@@ -48,6 +48,9 @@
 #define USART_AUTOFLOW_CTS      2
 #define USART_AUTOFLOW_OFF      0
 
+typedef unsigned int    uint;
+typedef uint8_t         register_t;
+
 /* stuctures for usart registers */
 struct IER 
 {
diff --git a/sw/z80/drivers/makefile b/sw/z80/drivers/makefile
new file mode 100644
index 0000000..5d6d8ee
--- /dev/null
+++ b/sw/z80/drivers/makefile
@@ -0,0 +1,22 @@
+# Drivers library
+
+LIB     := build/drivers.a
+SOURCES := $(wildcard *.c)
+OBJECTS := $(patsubst %.c,build/%.rel,$(SOURCES))
+
+CC := sdcc
+AR := sdar
+CFLAGS := -mz80 -Iinclude -I../arch -DDEBUG
+
+.PHONY: dirs clean
+$(LIB): $(OBJECTS)
+	$(AR) rcs $@ $(OBJECTS)
+
+$(OBJECTS): build/%.rel: %.c $(SOURCES) dirs
+	$(CC) $(CFLAGS) -c $< -o $@
+
+dirs:
+	mkdir -p build
+
+clean:
+	- rm -rd build/*
diff --git a/sw/z80/kernel/drivers/pio.c b/sw/z80/drivers/pio.c
index 4321fb8..bdbe1c3 100644
--- a/sw/z80/kernel/drivers/pio.c
+++ b/sw/z80/drivers/pio.c
@@ -1,4 +1,4 @@
-#include "drivers/pio.h"
+#include "pio.h"
 
 static uint8_t *pio_port = (uint8_t *) ADDR_DEV_PIO;
 static uint8_t *pio_ctrl = (uint8_t *) (ADDR_DEV_PIO + 2);
@@ -34,7 +34,17 @@ void pio_set_interrupts(int port, int control)
 void pio_set_interrupts_mask(int port, int control, uint8_t mask)
 {
     // 0x17 is a control sequence to set interrupts
-    // and to interpret the next byte as a mask
+    // AND interpret the next byte as a bitmask
     _pio_control(port, (control | 0x17));
     _pio_control(port, mask);
 }
+
+uint8_t pio_read(int port)
+{
+    return *(pio_port + port);
+}
+
+void pio_write(int port, uint8_t data)
+{
+    _pio_data(port, data);
+}
diff --git a/sw/z80/kernel/drivers/usart.c b/sw/z80/drivers/usart.c
index c54fe37..9ec6dbd 100644
--- a/sw/z80/kernel/drivers/usart.c
+++ b/sw/z80/drivers/usart.c
@@ -1,4 +1,4 @@
-#include "drivers/usart.h"
+#include "usart.h"
 
 static struct _usart_device *_usart = (struct _usart_device *) ADDR_DEV_USART;
 
diff --git a/sw/z80/crt0.s b/sw/z80/kernel/crt0.s
index 00c7da1..00c7da1 100644
--- a/sw/z80/crt0.s
+++ b/sw/z80/kernel/crt0.s
diff --git a/sw/z80/makefile b/sw/z80/kernel/makefile
index 5ab7e93..be8eed4 100644
--- a/sw/z80/makefile
+++ b/sw/z80/kernel/makefile
@@ -3,9 +3,8 @@
 #
 OSNAME := helvetiOS
  
-CSOURCES 	:=  $(wildcard kernel/*.c) \
-				$(wildcard kernel/drivers/*.c) \
-				$(wildcard libc/*.c) 
+CSOURCES 	:=  $(wildcard *.c) \
+				$(wildcard drivers/*.c)
 
 OBJECTS 	:= $(patsubst %.c,build/%.rel,$(CSOURCES))
 HEXFILE		:= build/$(OSNAME).hex
@@ -17,13 +16,13 @@ BINARY  	:= build/$(OSNAME).bin
 CC 		:= sdcc
 
 CFLAGS	:= -mz80 \
-			-I kernel/include \
-			-I kernel/include/drivers \
+			-I include \
+			-I include/drivers \
 			-I libc/include \
 			--opt-code-size \
 			-DDEBUG
 
-LDFLAGS := -mz80 --no-std-crt0 crt0.rel \
+LDFLAGS := -mz80 --no-std-crt0 build/crt0.rel \
 			--std-c89 -pedantic \
 			--code-loc 0x0800 --data-loc 0x8000
 
@@ -33,21 +32,20 @@ all: $(BINARY)
 # build binary
 $(BINARY): $(OBJECTS) dirs
 	$(CC) $(LDFLAGS) $(OBJECTS) -o $(HEXFILE)
-	@# xxd -r -p $(HEXFILE) $(BINARY)
 	makebin -s 16384 $(HEXFILE) $(BINARY)
 
-$(OBJECTS): build/%.rel : %.c $(CSOURCES) dirs crt0.rel
+$(OBJECTS): build/%.rel : %.c $(CSOURCES) dirs build/crt0.rel
 	@printf "\n"
 	$(CC) $(CFLAGS) -c $< -o $@
 
-crt0.rel: crt0.s
+build/crt0.rel: crt0.s
 	sdasz80 -o $<
+	@mv crt0.rel build
 
 dirs:
 	mkdir -p build build/kernel build/libc build/kernel/drivers
 
 dis: $(BINARY)
-	@# z80dasm -a -l -g 0h $< -o build/$(OSNAME).s
 	dz80 -b -n $<
 
 clean:
diff --git a/sw/z80_tests/usart/types.h b/sw/z80/libc/include/stdint.h
index 815fc68..5e8caf3 100644
--- a/sw/z80_tests/usart/types.h
+++ b/sw/z80/libc/include/stdint.h
@@ -1,13 +1,13 @@
-#ifndef __TYPES_H__
-#define __TYPES_H__
-
-/* only types from primitive types are defined in this file */ 
-
-typedef volatile unsigned char      register_t;
+#ifndef __STDINT_H__
+#define __STDINT_H__
 
 typedef unsigned int                uint;
+
 typedef char                        int8_t;
 typedef unsigned char               uint8_t;
 typedef int                         int16_t;
 typedef unsigned int                uint16_t;
-#endif
+typedef long int                    int32_t;
+typedef unsigned long int           uint32_t;
+
+#endif // __STDINT_H__
\ No newline at end of file
diff --git a/sw/z80/libc/include/stdlib.h b/sw/z80/libc/include/stdlib.h
new file mode 100644
index 0000000..c69f573
--- /dev/null
+++ b/sw/z80/libc/include/stdlib.h
@@ -0,0 +1,7 @@
+#ifndef __STDLIB_H__
+#define __STDLIB_H__
+
+#include "stdint.h"
+
+
+#endif // __STDLIB_H__
\ No newline at end of file
diff --git a/sw/z80/libc/include/types.h b/sw/z80/libc/include/types.h
new file mode 100644
index 0000000..a083bfe
--- /dev/null
+++ b/sw/z80/libc/include/types.h
@@ -0,0 +1,60 @@
+#ifndef __TYPES_H__
+#define __TYPES_H__
+
+/* only types from primitive types are defined in this file */ 
+
+typedef volatile unsigned char      register_t;
+
+typedef unsigned int                uint;
+
+typedef char                        int8_t;
+typedef unsigned char               uint8_t;
+typedef int                         int16_t;
+typedef unsigned int                uint16_t;
+typedef long int                    int32_t;
+typedef unsigned long int           uint32_t;
+
+typedef uint16_t                    size_t;
+typedef int16_t                     ssize_t;
+
+typedef uint8_t                     pid_t;
+typedef uint16_t                    ino_t;
+
+typedef uint8_t                     dev_t;
+typedef uint32_t                    devsize_t;
+typedef uint8_t                     fd_t;
+typedef uint16_t                    blk_t;
+typedef uint8_t                     user_t; 
+typedef struct {
+    uint8_t member[3];
+} uint24_t;
+
+typedef uint32_t                    fsize_t;
+
+typedef struct 
+{
+    dev_t   dev;    // device id, global in the fs
+    ino_t   inode;    // inode id relative to the volume
+
+} inode_t;
+
+typedef struct time_s
+{
+    struct
+    {
+        uint    minutes :6;
+        uint    hour    :5;
+
+    } time;
+
+    struct
+    {
+        uint    day     :5;
+        uint    month   :4;
+        uint    year    :12;
+
+    } date;
+
+} time_t;
+
+#endif
diff --git a/sw/z80_tests/usart/build/crt0.rel b/sw/z80/tests/pio/build/crt0.rel
index 809c0e6..809c0e6 100644
--- a/sw/z80_tests/usart/build/crt0.rel
+++ b/sw/z80/tests/pio/build/crt0.rel
diff --git a/sw/z80_tests/usart/build/main.asm b/sw/z80/tests/pio/build/main.asm
index 44f199a..453eead 100644
--- a/sw/z80_tests/usart/build/main.asm
+++ b/sw/z80/tests/pio/build/main.asm
@@ -9,8 +9,8 @@
 ; Public variables in this module
 ;--------------------------------------------------------
 	.globl _main
-	.globl _usart_write
-	.globl _usart_init
+	.globl _pio_write
+	.globl _pio_set_mode
 ;--------------------------------------------------------
 ; special function registers
 ;--------------------------------------------------------
@@ -47,44 +47,34 @@
 ; Function main
 ; ---------------------------------
 _main::
-;main.c:5: usart_init(USART_BAUDRATE_1200, USART_PARITY_EVEN, USART_STOP_BITS_1);
-	ld	hl,#0x000a
+;main.c:7: pio_set_mode(PIO_A, PIO_MODE_BYTE_OUT, 0);
+	xor	a, a
+	push	af
+	inc	sp
+	ld	hl,#0x0001
 	push	hl
-	ld	l, #0x01
+	ld	l, #0x00
 	push	hl
-	ld	l, #0x60
-	push	hl
-	call	_usart_init
-	ld	hl,#6
-	add	hl,sp
-	ld	sp,hl
-;main.c:6: usart_write("Hello, World!\n", 13);
-	ld	hl,#0x000d
-	push	hl
-	ld	hl,#___str_0
-	push	hl
-	call	_usart_write
+	call	_pio_set_mode
 	pop	af
 	pop	af
-;main.c:8: while(1) {
+	inc	sp
+;main.c:9: while (1) {
+	ld	c,#0x00
 00102$:
-;main.c:9: usart_write("done\n", 5);
-	ld	hl,#0x0005
+;main.c:10: pio_write(PIO_A, j++);
+	ld	b,c
+	inc	c
+	push	bc
+	push	bc
+	inc	sp
+	ld	hl,#0x0000
 	push	hl
-	ld	hl,#___str_1
-	push	hl
-	call	_usart_write
-	pop	af
+	call	_pio_write
 	pop	af
+	inc	sp
+	pop	bc
 	jr	00102$
-___str_0:
-	.ascii "Hello, World!"
-	.db 0x0a
-	.db 0x00
-___str_1:
-	.ascii "done"
-	.db 0x0a
-	.db 0x00
 	.area _CODE
 	.area _INITIALIZER
 	.area _CABS (ABS)
diff --git a/sw/z80_tests/usart/build/main.lst b/sw/z80/tests/pio/build/main.lst
index c7b4201..4a1a872 100644
--- a/sw/z80_tests/usart/build/main.lst
+++ b/sw/z80/tests/pio/build/main.lst
@@ -9,8 +9,8 @@
                               9 ; Public variables in this module
                              10 ;--------------------------------------------------------
                              11 	.globl _main
-                             12 	.globl _usart_write
-                             13 	.globl _usart_init
+                             12 	.globl _pio_write
+                             13 	.globl _pio_set_mode
                              14 ;--------------------------------------------------------
                              15 ; special function registers
                              16 ;--------------------------------------------------------
@@ -47,46 +47,34 @@
                              47 ; Function main
                              48 ; ---------------------------------
    0000                      49 _main::
-                             50 ;main.c:5: usart_init(USART_BAUDRATE_1200, USART_PARITY_EVEN, USART_STOP_BITS_1);
-   0000 21 0A 00      [10]   51 	ld	hl,#0x000a
-   0003 E5            [11]   52 	push	hl
-   0004 2E 01         [ 7]   53 	ld	l, #0x01
-   0006 E5            [11]   54 	push	hl
-   0007 2E 60         [ 7]   55 	ld	l, #0x60
-   0009 E5            [11]   56 	push	hl
-   000A CDr00r00      [17]   57 	call	_usart_init
-   000D 21 06 00      [10]   58 	ld	hl,#6
-   0010 39            [11]   59 	add	hl,sp
-   0011 F9            [ 6]   60 	ld	sp,hl
-                             61 ;main.c:6: usart_write("Hello, World!\n", 13);
-   0012 21 0D 00      [10]   62 	ld	hl,#0x000d
-   0015 E5            [11]   63 	push	hl
-   0016 21r2Er00      [10]   64 	ld	hl,#___str_0
-   0019 E5            [11]   65 	push	hl
-   001A CDr00r00      [17]   66 	call	_usart_write
-   001D F1            [10]   67 	pop	af
-   001E F1            [10]   68 	pop	af
-                             69 ;main.c:8: while(1) {
-   001F                      70 00102$:
-                             71 ;main.c:9: usart_write("done\n", 5);
-   001F 21 05 00      [10]   72 	ld	hl,#0x0005
-   0022 E5            [11]   73 	push	hl
-   0023 21r3Dr00      [10]   74 	ld	hl,#___str_1
-   0026 E5            [11]   75 	push	hl
-   0027 CDr00r00      [17]   76 	call	_usart_write
-   002A F1            [10]   77 	pop	af
-   002B F1            [10]   78 	pop	af
-   002C 18 F1         [12]   79 	jr	00102$
-   002E                      80 ___str_0:
-   002E 48 65 6C 6C 6F 2C    81 	.ascii "Hello, World!"
-        20 57 6F 72 6C 64
-        21
-   003B 0A                   82 	.db 0x0a
-   003C 00                   83 	.db 0x00
-   003D                      84 ___str_1:
-   003D 64 6F 6E 65          85 	.ascii "done"
-   0041 0A                   86 	.db 0x0a
-   0042 00                   87 	.db 0x00
-                             88 	.area _CODE
-                             89 	.area _INITIALIZER
-                             90 	.area _CABS (ABS)
+                             50 ;main.c:7: pio_set_mode(PIO_A, PIO_MODE_BYTE_OUT, 0);
+   0000 AF            [ 4]   51 	xor	a, a
+   0001 F5            [11]   52 	push	af
+   0002 33            [ 6]   53 	inc	sp
+   0003 21 01 00      [10]   54 	ld	hl,#0x0001
+   0006 E5            [11]   55 	push	hl
+   0007 2E 00         [ 7]   56 	ld	l, #0x00
+   0009 E5            [11]   57 	push	hl
+   000A CDr00r00      [17]   58 	call	_pio_set_mode
+   000D F1            [10]   59 	pop	af
+   000E F1            [10]   60 	pop	af
+   000F 33            [ 6]   61 	inc	sp
+                             62 ;main.c:9: while (1) {
+   0010 0E 00         [ 7]   63 	ld	c,#0x00
+   0012                      64 00102$:
+                             65 ;main.c:10: pio_write(PIO_A, j++);
+   0012 41            [ 4]   66 	ld	b,c
+   0013 0C            [ 4]   67 	inc	c
+   0014 C5            [11]   68 	push	bc
+   0015 C5            [11]   69 	push	bc
+   0016 33            [ 6]   70 	inc	sp
+   0017 21 00 00      [10]   71 	ld	hl,#0x0000
+   001A E5            [11]   72 	push	hl
+   001B CDr00r00      [17]   73 	call	_pio_write
+   001E F1            [10]   74 	pop	af
+   001F 33            [ 6]   75 	inc	sp
+   0020 C1            [10]   76 	pop	bc
+   0021 18 EF         [12]   77 	jr	00102$
+                             78 	.area _CODE
+                             79 	.area _INITIALIZER
+                             80 	.area _CABS (ABS)
diff --git a/sw/z80/tests/pio/build/main.rel b/sw/z80/tests/pio/build/main.rel
new file mode 100644
index 0000000..bc2bd98
--- /dev/null
+++ b/sw/z80/tests/pio/build/main.rel
@@ -0,0 +1,29 @@
+XL2
+H 9 areas 4 global symbols
+M main
+O -mz80
+S _pio_set_mode Ref0000
+S .__.ABS. Def0000
+S _pio_write Ref0000
+A _CODE size 23 flags 0 addr 0
+S _main Def0000
+A _DATA size 0 flags 0 addr 0
+A _INITIALIZED size 0 flags 0 addr 0
+A _DABS size 0 flags 8 addr 0
+A _HOME size 0 flags 0 addr 0
+A _GSINIT size 0 flags 0 addr 0
+A _GSFINAL size 0 flags 0 addr 0
+A _INITIALIZER size 0 flags 0 addr 0
+A _CABS size 0 flags 8 addr 0
+T 00 00
+R 00 00 00 00
+T 00 00 AF F5 33 21 01 00 E5 2E 00 E5 CD 00 00 F1
+R 00 00 00 00 02 0D 00 00
+T 0E 00 F1 33 0E 00
+R 00 00 00 00
+T 12 00
+R 00 00 00 00
+T 12 00 41 0C C5 C5 33 21 00 00 E5 CD 00 00 F1 33
+R 00 00 00 00 02 0C 02 00
+T 20 00 C1 18 EF
+R 00 00 00 00
diff --git a/sw/z80_tests/usart/build/main.sym b/sw/z80/tests/pio/build/main.sym
index df02e0d..08d28a3 100644
--- a/sw/z80_tests/usart/build/main.sym
+++ b/sw/z80/tests/pio/build/main.sym
@@ -7,18 +7,17 @@ Symbol Table
     .__.ABS.                                                    =  0000 G
     .__.CPU.                                                    =  0000 L
     .__.H$L.                                                    =  0000 L
-  0 ___str_0                                                       002E R
-  0 ___str_1                                                       003D R
   0 _main                                                          0000 GR
-    _usart_init                                                    **** GX
-    _usart_write                                                   **** GX
+    _pio_set_mode                                                  **** GX
+    _pio_write                                                     **** GX
+
 
 ASxxxx Assembler V02.00 + NoICE + SDCC mods  (Zilog Z80 / Hitachi HD64180), page 2.
 Hexadecimal [16-Bits]
 
 Area Table
 
-   0 _CODE                                      size   43   flags    0
+   0 _CODE                                      size   23   flags    0
    1 _DATA                                      size    0   flags    0
    2 _INITIALIZED                               size    0   flags    0
    3 _DABS                                      size    0   flags    8
diff --git a/sw/z80_tests/usart/build/sample.lk b/sw/z80/tests/pio/build/pio_test.lk
index dc99ff1..20c32cc 100644
--- a/sw/z80_tests/usart/build/sample.lk
+++ b/sw/z80/tests/pio/build/pio_test.lk
@@ -1,12 +1,13 @@
 -mjwx
--i build/sample.hex
+-i build/pio_test.hex
 -b _CODE = 0x0800
 -b _DATA = 0x2000
+-k ../../drivers/build/
 -k /usr/libexec/../share/sdcc/lib/z80
 -k /usr/share/sdcc/lib/z80
+-l drivers.a
 -l z80
 build/crt0.rel
 build/main.rel
-build/usart.rel
 
 -e
diff --git a/sw/z80_tests/usart/build/sample.map b/sw/z80/tests/pio/build/pio_test.map
index e812f09..e91ef69 100644
--- a/sw/z80_tests/usart/build/sample.map
+++ b/sw/z80/tests/pio/build/pio_test.map
@@ -7,7 +7,7 @@ Area                                    Addr        Size        Decimal Bytes (A
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
-     00000000  .__.ABS.                           usart
+     00000000  .__.ABS.                           pio
      00000000  l__BSEG                         
      00000000  l__BSS                          
      00000000  l__CABS                         
@@ -36,44 +36,41 @@ Area                                    Addr        Size        Decimal Bytes (A
      00000002  l__HEADER5                      
      00000002  l__HEADER6                      
      00000002  l__HEADER7                      
-     00000002  l__INITIALIZED                  
-     00000002  l__INITIALIZER                  
      00000003  l__HEADER0                      
+     00000004  l__INITIALIZED                  
+     00000004  l__INITIALIZER                  
      00000006  l__GSINIT                       
      0000000C  l__HEADER8                      
-     00000264  l__CODE                         
+     000000FD  l__CODE                         
      00000800  s__CODE                         
-     00000A64  s__HOME                         
-     00000A64  s__INITIALIZER                  
-     00000A66  s__GSINIT                       
-     00000A6C  s__GSFINAL                      
+     000008FD  s__HOME                         
+     000008FD  s__INITIALIZER                  
+     00000901  s__GSINIT                       
+     00000907  s__GSFINAL                      
      00002000  s__DATA                         
      00002000  s__INITIALIZED                  
-     00002002  s__BSEG                         
-     00002002  s__BSS                          
-     00002002  s__HEAP                         
+     00002004  s__BSEG                         
+     00002004  s__BSS                          
+     00002004  s__HEAP                         
 ASxxxx Linker V03.00 + NoICE + sdld,  page 2.
 Hexadecimal  [32-Bits]
 
 Area                                    Addr        Size        Decimal Bytes (Attributes)
 --------------------------------        ----        ----        ------- ----- ------------
-_CODE                               00000800    00000264 =         612. bytes (REL,CON)
+_CODE                               00000800    000000FD =         253. bytes (REL,CON)
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
      00000800  __clock                            crt0
      00000804  _exit                              crt0
      0000080A  _main                              main
-     0000084D  _usart_set_baudrate                usart
-     00000881  _usart_set_parity                  usart
-     000008D5  _usart_set_stop_bits               usart
-     00000902  _usart_word_length                 usart
-     0000091B  _usart_set_autoflow                usart
-     00000955  _usart_init                        usart
-     0000097E  _usart_transmit                    usart
-     00000999  _usart_receive                     usart
-     0000099E  _usart_write                       usart
-     000009E5  _usart_read                        usart
+     0000082D  __pio_data                         pio
+     00000847  __pio_control                      pio
+     00000861  _pio_set_mode                      pio
+     0000089D  _pio_set_interrupts                pio
+     000008B0  _pio_set_interrupts_mask           pio
+     000008D7  _pio_read                          pio
+     000008ED  _pio_write                         pio
 
 ASxxxx Linker V03.00 + NoICE + sdld,  page 3.
 Hexadecimal  [32-Bits]
@@ -161,7 +158,7 @@ Hexadecimal  [32-Bits]
 
 Area                                    Addr        Size        Decimal Bytes (Attributes)
 --------------------------------        ----        ----        ------- ----- ------------
-_INITIALIZER                        00000A64    00000002 =           2. bytes (REL,CON)
+_INITIALIZER                        000008FD    00000004 =           4. bytes (REL,CON)
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
@@ -170,18 +167,18 @@ Hexadecimal  [32-Bits]
 
 Area                                    Addr        Size        Decimal Bytes (Attributes)
 --------------------------------        ----        ----        ------- ----- ------------
-_GSINIT                             00000A66    00000006 =           6. bytes (REL,CON)
+_GSINIT                             00000901    00000006 =           6. bytes (REL,CON)
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
-     00000A66  gsinit                             crt0
+     00000901  gsinit                             crt0
 
 ASxxxx Linker V03.00 + NoICE + sdld,  page 14.
 Hexadecimal  [32-Bits]
 
 Area                                    Addr        Size        Decimal Bytes (Attributes)
 --------------------------------        ----        ----        ------- ----- ------------
-_GSFINAL                            00000A6C    00000001 =           1. bytes (REL,CON)
+_GSFINAL                            00000907    00000001 =           1. bytes (REL,CON)
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
@@ -190,7 +187,7 @@ Hexadecimal  [32-Bits]
 
 Area                                    Addr        Size        Decimal Bytes (Attributes)
 --------------------------------        ----        ----        ------- ----- ------------
-_INITIALIZED                        00002000    00000002 =           2. bytes (REL,CON)
+_INITIALIZED                        00002000    00000004 =           4. bytes (REL,CON)
 
       Value  Global                              Global Defined In Module
       -----  --------------------------------   ------------------------
@@ -200,7 +197,11 @@ Files Linked                              [ module(s) ]
 
 build/crt0.rel                            [ crt0 ]
 build/main.rel                            [ main ]
-build/usart.rel                           [ usart ]
+
+
+Libraries Linked                          [ object file ]
+
+../../drivers/build/drivers.a             [ pio.rel ]
 
 ASxxxx Linker V03.00 + NoICE + sdld,  page 17.
 
diff --git a/sw/z80_tests/usart/build/sample.noi b/sw/z80/tests/pio/build/pio_test.noi
index 6d97288..3ddefe7 100644
--- a/sw/z80_tests/usart/build/sample.noi
+++ b/sw/z80/tests/pio/build/pio_test.noi
@@ -27,34 +27,31 @@ DEF l__HEADER4 0x2
 DEF l__HEADER5 0x2
 DEF l__HEADER6 0x2
 DEF l__HEADER7 0x2
-DEF l__INITIALIZED 0x2
-DEF l__INITIALIZER 0x2
 DEF l__HEADER0 0x3
+DEF l__INITIALIZED 0x4
+DEF l__INITIALIZER 0x4
 DEF l__GSINIT 0x6
 DEF l__HEADER8 0xC
-DEF l__CODE 0x264
+DEF l__CODE 0xFD
 DEF s__CODE 0x800
-DEF s__HOME 0xA64
-DEF s__INITIALIZER 0xA64
-DEF s__GSINIT 0xA66
-DEF s__GSFINAL 0xA6C
+DEF s__HOME 0x8FD
+DEF s__INITIALIZER 0x8FD
+DEF s__GSINIT 0x901
+DEF s__GSFINAL 0x907
 DEF s__DATA 0x2000
 DEF s__INITIALIZED 0x2000
-DEF s__BSEG 0x2002
-DEF s__BSS 0x2002
-DEF s__HEAP 0x2002
+DEF s__BSEG 0x2004
+DEF s__BSS 0x2004
+DEF s__HEAP 0x2004
 DEF __clock 0x800
 DEF _exit 0x804
 DEF _main 0x80A
-DEF _usart_set_baudrate 0x84D
-DEF _usart_set_parity 0x881
-DEF _usart_set_stop_bits 0x8D5
-DEF _usart_word_length 0x902
-DEF _usart_set_autoflow 0x91B
-DEF _usart_init 0x955
-DEF _usart_transmit 0x97E
-DEF _usart_receive 0x999
-DEF _usart_write 0x99E
-DEF _usart_read 0x9E5
-DEF gsinit 0xA66
-LOAD build/sample.ihx
+DEF __pio_data 0x82D
+DEF __pio_control 0x847
+DEF _pio_set_mode 0x861
+DEF _pio_set_interrupts 0x89D
+DEF _pio_set_interrupts_mask 0x8B0
+DEF _pio_read 0x8D7
+DEF _pio_write 0x8ED
+DEF gsinit 0x901
+LOAD build/pio_test.ihx
diff --git a/sw/z80_tests/usart/crt0.s b/sw/z80/tests/pio/crt0.s
index c272f06..c272f06 100644
--- a/sw/z80_tests/usart/crt0.s
+++ b/sw/z80/tests/pio/crt0.s
diff --git a/sw/z80/tests/pio/main.c b/sw/z80/tests/pio/main.c
new file mode 100644
index 0000000..4b0bcdb
--- /dev/null
+++ b/sw/z80/tests/pio/main.c
@@ -0,0 +1,12 @@
+#include "pio.h"
+
+void main(void)
+{
+    uint8_t j = 0;
+
+    pio_set_mode(PIO_A, PIO_MODE_BYTE_OUT, 0);
+
+    while (1) {
+        pio_write(PIO_A, j++);
+    }
+}
diff --git a/sw/z80_tests/usart/makefile b/sw/z80/tests/pio/makefile
index 080f41c..bd9d5bf 100644
--- a/sw/z80_tests/usart/makefile
+++ b/sw/z80/tests/pio/makefile
@@ -1,13 +1,13 @@
 ####
 # source code settings
 #
-OSNAME := sample
+NAME := pio_test
  
-CSOURCES 	:=  $(wildcard *.c)
+CSOURCES 	:= $(wildcard *.c)
 
 OBJECTS 	:= $(patsubst %.c,build/%.rel,$(CSOURCES))
-HEXFILE		:= build/$(OSNAME).hex
-BINARY  	:= build/$(OSNAME).bin
+HEXFILE		:= build/$(NAME).hex
+BINARY  	:= build/$(NAME).bin
 
 ### 
 # compiler settings
@@ -15,12 +15,18 @@ BINARY  	:= build/$(OSNAME).bin
 CC 		:= sdcc
 
 CFLAGS	:= -mz80 \
+			-pedantic \
 			-I . \
+			-I ../../arch \
+			-I ../../drivers/include \
 			-DDEBUG
 
-LDFLAGS := -mz80 --no-std-crt0 build/crt0.rel \
-			--std-c89 -pedantic \
-			--code-loc 0x0800 --data-loc 0x2000
+LDFLAGS := -mz80 \
+			-L ../../drivers/build/ \
+			-l drivers.a \
+			--no-std-crt0 build/crt0.rel \
+			--code-loc 0x0800 \
+			--data-loc 0x2000
 
 .PHONY: dirs dis clean
 all: $(BINARY)
@@ -28,8 +34,6 @@ all: $(BINARY)
 # build binary
 $(BINARY): $(OBJECTS) dirs
 	$(CC) $(LDFLAGS) $(OBJECTS) -o $(HEXFILE)
-	@# xxd -r -p $(HEXFILE) $(BINARY)
-	@# makebin -s 16384 $(HEXFILE) $(BINARY)
 	makebin -s 8192 $(HEXFILE) $(BINARY)
 
 $(OBJECTS): build/%.rel : %.c $(CSOURCES) dirs build/crt0.rel
diff --git a/sw/z80_tests/ram/build/crt0.rel b/sw/z80/tests/ram/build/crt0.rel
index cce6a25..b9ed132 100644
--- a/sw/z80_tests/ram/build/crt0.rel
+++ b/sw/z80/tests/ram/build/crt0.rel
@@ -1,5 +1,5 @@
 XL2
-H 14 areas 3 global symbols
+H 15 areas 3 global symbols
 M crt0
 S _main Ref0000
 S .__.ABS. Def0000
@@ -14,7 +14,8 @@ A _HEADER4 size 2 flags 8 addr 20
 A _HEADER5 size 2 flags 8 addr 28
 A _HEADER6 size 2 flags 8 addr 30
 A _HEADER7 size 2 flags 8 addr 38
-A _HEADER8 size 9 flags 8 addr 100
+A _HEADER8 size 2 flags 8 addr 66
+A _HEADER9 size 9 flags 8 addr 100
 A _HOME size 0 flags 0 addr 0
 A _INITIALIZER size 0 flags 0 addr 0
 A _GSINIT size 0 flags 0 addr 0
@@ -27,7 +28,7 @@ A _HEAP size 0 flags 0 addr 0
 T 00 00
 R 00 00 02 00
 T 00 00 C3 00 01
-R 00 00 02 00 00 03 0A 00
+R 00 00 02 00 00 03 0B 00
 T 08 00
 R 00 00 03 00
 T 08 00 ED 4D
@@ -56,12 +57,16 @@ T 38 00
 R 00 00 09 00
 T 38 00 ED 4D
 R 00 00 09 00
-T 00 01
+T 66 00
 R 00 00 0A 00
-T 00 01
+T 66 00 ED 4D
 R 00 00 0A 00
+T 00 01
+R 00 00 0B 00
+T 00 01
+R 00 00 0B 00
 T 00 01 31 FF FF CD 00 00 C3 00 00
-R 00 00 0A 00 02 06 00 00 00 09 00 00
+R 00 00 0B 00 02 06 00 00 00 09 00 00
 T 00 00
 R 00 00 00 00
 T 00 00
diff --git a/sw/z80_tests/ram/build/main.asm b/sw/z80/tests/ram/build/main.asm
index f3b8add..f3b8add 100644
--- a/sw/z80_tests/ram/build/main.asm
+++ b/sw/z80/tests/ram/build/main.asm
diff --git a/sw/z80_tests/ram/build/main.lst b/sw/z80/tests/ram/build/main.lst
index 17142d4..17142d4 100644
--- a/sw/z80_tests/ram/build/main.lst
+++ b/sw/z80/tests/ram/build/main.lst
diff --git a/sw/z80_tests/ram/build/main.rel b/sw/z80/tests/ram/build/main.rel
index cad7a3c..cad7a3c 100644
--- a/sw/z80_tests/ram/build/main.rel
+++ b/sw/z80/tests/ram/build/main.rel
diff --git a/sw/z80_tests/ram/build/main.sym b/sw/z80/tests/ram/build/main.sym
index d81bdc8..d81bdc8 100644
--- a/sw/z80_tests/ram/build/main.sym
+++ b/sw/z80/tests/ram/build/main.sym
diff --git a/sw/z80/tests/ram/build/ram_test.lk b/sw/z80/tests/ram/build/ram_test.lk
new file mode 100644
index 0000000..724eb89
--- /dev/null
+++ b/sw/z80/tests/ram/build/ram_test.lk
@@ -0,0 +1,11 @@
+-mjwx
+-i build/ram_test.hex
+-b _CODE = 0x0000
+-b _DATA = 0x2000
+-k /usr/libexec/../share/sdcc/lib/z80
+-k /usr/share/sdcc/lib/z80
+-l z80
+build/crt0.rel
+build/main.rel
+
+-e
diff --git a/sw/z80/tests/ram/build/ram_test.map b/sw/z80/tests/ram/build/ram_test.map
new file mode 100644
index 0000000..0d36247
--- /dev/null
+++ b/sw/z80/tests/ram/build/ram_test.map
@@ -0,0 +1,174 @@
+ASxxxx Linker V03.00 + NoICE + sdld,  page 1.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+.  .ABS.                            00000000    00000000 =           0. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+     00000000  .__.ABS.                           main
+     00000000  l__BSEG                         
+     00000000  l__BSS                          
+     00000000  l__CABS                         
+     00000000  l__DABS                         
+     00000000  l__DATA                         
+     00000000  l__GSFINAL                      
+     00000000  l__GSINIT                       
+     00000000  l__HEADER                       
+     00000000  l__HEAP                         
+     00000000  l__HOME                         
+     00000000  l__INITIALIZED                  
+     00000000  l__INITIALIZER                  
+     00000000  s__CABS                         
+     00000000  s__CODE                         
+     00000000  s__DABS                         
+     00000000  s__HEADER                       
+     00000000  s__HEADER0                      
+     00000000  s__HEADER1                      
+     00000000  s__HEADER2                      
+     00000000  s__HEADER3                      
+     00000000  s__HEADER4                      
+     00000000  s__HEADER5                      
+     00000000  s__HEADER6                      
+     00000000  s__HEADER7                      
+     00000000  s__HEADER8                      
+     00000000  s__HEADER9                      
+     00000002  l__HEADER1                      
+     00000002  l__HEADER2                      
+     00000002  l__HEADER3                      
+     00000002  l__HEADER4                      
+     00000002  l__HEADER5                      
+     00000002  l__HEADER6                      
+     00000002  l__HEADER7                      
+     00000002  l__HEADER8                      
+     00000003  l__HEADER0                      
+     00000009  l__HEADER9                      
+     0000000D  l__CODE                         
+     0000000D  s__GSFINAL                      
+     0000000D  s__GSINIT                       
+     0000000D  s__HOME                         
+     0000000D  s__INITIALIZER                  
+     00002000  s__BSEG                         
+     00002000  s__BSS                          
+     00002000  s__DATA                         
+     00002000  s__HEAP                         
+     00002000  s__INITIALIZED                  
+
+ASxxxx Linker V03.00 + NoICE + sdld,  page 2.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_CODE                               00000000    0000000D =          13. bytes (REL,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+     00000000  _exit                              crt0
+     00000003  _main                              main
+
+ASxxxx Linker V03.00 + NoICE + sdld,  page 3.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER0                            00000000    00000003 =           3. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 4.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER1                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 5.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER2                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 6.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER3                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 7.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER4                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 8.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER5                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 9.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER6                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 10.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER7                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 11.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER8                            00000000    00000002 =           2. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 12.
+Hexadecimal  [32-Bits]
+
+Area                                    Addr        Size        Decimal Bytes (Attributes)
+--------------------------------        ----        ----        ------- ----- ------------
+_HEADER9                            00000000    00000009 =           9. bytes (ABS,CON)
+
+      Value  Global                              Global Defined In Module
+      -----  --------------------------------   ------------------------
+ASxxxx Linker V03.00 + NoICE + sdld,  page 13.
+
+Files Linked                              [ module(s) ]
+
+build/crt0.rel                            [ crt0 ]
+build/main.rel                            [ main ]
+
+ASxxxx Linker V03.00 + NoICE + sdld,  page 14.
+
+User Base Address Definitions
+
+_CODE = 0x0000
+_DATA = 0x2000
+
+
\ No newline at end of file
diff --git a/sw/z80/tests/ram/build/ram_test.noi b/sw/z80/tests/ram/build/ram_test.noi
new file mode 100644
index 0000000..94266c5
--- /dev/null
+++ b/sw/z80/tests/ram/build/ram_test.noi
@@ -0,0 +1,50 @@
+DEF .__.ABS. 0x0
+DEF l__BSEG 0x0
+DEF l__BSS 0x0
+DEF l__CABS 0x0
+DEF l__DABS 0x0
+DEF l__DATA 0x0
+DEF l__GSFINAL 0x0
+DEF l__GSINIT 0x0
+DEF l__HEADER 0x0
+DEF l__HEAP 0x0
+DEF l__HOME 0x0
+DEF l__INITIALIZED 0x0
+DEF l__INITIALIZER 0x0
+DEF s__CABS 0x0
+DEF s__CODE 0x0
+DEF s__DABS 0x0
+DEF s__HEADER 0x0
+DEF s__HEADER0 0x0
+DEF s__HEADER1 0x0
+DEF s__HEADER2 0x0
+DEF s__HEADER3 0x0
+DEF s__HEADER4 0x0
+DEF s__HEADER5 0x0
+DEF s__HEADER6 0x0
+DEF s__HEADER7 0x0
+DEF s__HEADER8 0x0
+DEF s__HEADER9 0x0
+DEF l__HEADER1 0x2
+DEF l__HEADER2 0x2
+DEF l__HEADER3 0x2
+DEF l__HEADER4 0x2
+DEF l__HEADER5 0x2
+DEF l__HEADER6 0x2
+DEF l__HEADER7 0x2
+DEF l__HEADER8 0x2
+DEF l__HEADER0 0x3
+DEF l__HEADER9 0x9
+DEF l__CODE 0xD
+DEF s__GSFINAL 0xD
+DEF s__GSINIT 0xD
+DEF s__HOME 0xD
+DEF s__INITIALIZER 0xD
+DEF s__BSEG 0x2000
+DEF s__BSS 0x2000
+DEF s__DATA 0x2000
+DEF s__HEAP 0x2000
+DEF s__INITIALIZED 0x2000
+DEF _exit 0x0
+DEF _main 0x3
+LOAD build/ram_test.ihx
diff --git a/sw/z80_tests/ram/build/test.lk b/sw/z80/tests/ram/build/test.lk
index 03a8db4..03a8db4 100644
--- a/sw/z80_tests/ram/build/test.lk
+++ b/sw/z80/tests/ram/build/test.lk
diff --git a/sw/z80_tests/ram/build/test.map b/sw/z80/tests/ram/build/test.map
index 07b953f..07b953f 100644
--- a/sw/z80_tests/ram/build/test.map
+++ b/sw/z80/tests/ram/build/test.map
diff --git a/sw/z80_tests/ram/build/test.noi b/sw/z80/tests/ram/build/test.noi
index 403beda..403beda 100644
--- a/sw/z80_tests/ram/build/test.noi
+++ b/sw/z80/tests/ram/build/test.noi
diff --git a/sw/z80_tests/ram/build/test.z80 b/sw/z80/tests/ram/build/test.z80
index 25a162a..25a162a 100644
--- a/sw/z80_tests/ram/build/test.z80
+++ b/sw/z80/tests/ram/build/test.z80
diff --git a/sw/z80_tests/ram/crt0.s b/sw/z80/tests/ram/crt0.s
index ac0698f..d775e66 100644
--- a/sw/z80_tests/ram/crt0.s
+++ b/sw/z80/tests/ram/crt0.s
@@ -21,7 +21,6 @@
 	.org	0x38
 	reti
     .org    0x66
-    ld hl,#BEEF
     reti
 
 	.org	0x100
diff --git a/sw/z80_tests/ram/main.c b/sw/z80/tests/ram/main.c
index 581072b..581072b 100644
--- a/sw/z80_tests/ram/main.c
+++ b/sw/z80/tests/ram/main.c
diff --git a/sw/z80_tests/ram/makefile b/sw/z80/tests/ram/makefile
index 35d7419..b8435a7 100644
--- a/sw/z80_tests/ram/makefile
+++ b/sw/z80/tests/ram/makefile
@@ -1,7 +1,7 @@
 ####
 # source code settings
 #
-OSNAME := test
+OSNAME := ram_test
  
 CSOURCES 	:=  $(wildcard *.c)
 
diff --git a/sw/z80_tests/usart/build/main.rel b/sw/z80_tests/usart/build/main.rel
deleted file mode 100644
index 2557016..0000000
--- a/sw/z80_tests/usart/build/main.rel
+++ /dev/null
@@ -1,41 +0,0 @@
-XL2
-H 9 areas 4 global symbols
-M main
-O -mz80
-S _usart_write Ref0000
-S .__.ABS. Def0000
-S _usart_init Ref0000
-A _CODE size 43 flags 0 addr 0
-S _main Def0000
-A _DATA size 0 flags 0 addr 0
-A _INITIALIZED size 0 flags 0 addr 0
-A _DABS size 0 flags 8 addr 0
-A _HOME size 0 flags 0 addr 0
-A _GSINIT size 0 flags 0 addr 0
-A _GSFINAL size 0 flags 0 addr 0
-A _INITIALIZER size 0 flags 0 addr 0
-A _CABS size 0 flags 8 addr 0
-T 00 00
-R 00 00 00 00
-T 00 00 21 0A 00 E5 2E 01 E5 2E 60 E5 CD 00 00 21
-R 00 00 00 00 02 0D 02 00
-T 0E 00 06 00 39 F9 21 0D 00 E5 21 2E 00 E5 CD
-R 00 00 00 00 00 0B 00 00
-T 1B 00 00 00 F1 F1
-R 00 00 00 00 02 02 00 00
-T 1F 00
-R 00 00 00 00
-T 1F 00 21 05 00 E5 21 3D 00 E5 CD 00 00 F1 F1 18
-R 00 00 00 00 00 07 00 00 02 0B 00 00
-T 2D 00 F1
-R 00 00 00 00
-T 2E 00
-R 00 00 00 00
-T 2E 00 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A
-R 00 00 00 00
-T 3C 00 00
-R 00 00 00 00
-T 3D 00
-R 00 00 00 00
-T 3D 00 64 6F 6E 65 0A 00
-R 00 00 00 00
diff --git a/sw/z80_tests/usart/build/pio.lst b/sw/z80_tests/usart/build/pio.lst
deleted file mode 100644
index fcafc2a..0000000
--- a/sw/z80_tests/usart/build/pio.lst
+++ /dev/null
@@ -1,194 +0,0 @@
-                              1 ;--------------------------------------------------------
-                              2 ; File Created by SDCC : free open source ANSI-C Compiler
-                              3 ; Version 3.6.0 #9615 (Linux)
-                              4 ;--------------------------------------------------------
-                              5 	.module pio
-                              6 	.optsdcc -mz80
-                              7 	
-                              8 ;--------------------------------------------------------
-                              9 ; Public variables in this module
-                             10 ;--------------------------------------------------------
-                             11 	.globl __pio_data
-                             12 	.globl __pio_control
-                             13 	.globl _pio_set_mode
-                             14 	.globl _pio_set_interrupts
-                             15 	.globl _pio_set_interrupts_mask
-                             16 ;--------------------------------------------------------
-                             17 ; special function registers
-                             18 ;--------------------------------------------------------
-                             19 ;--------------------------------------------------------
-                             20 ; ram data
-                             21 ;--------------------------------------------------------
-                             22 	.area _DATA
-                             23 ;--------------------------------------------------------
-                             24 ; ram data
-                             25 ;--------------------------------------------------------
-                             26 	.area _INITIALIZED
-   0000                      27 _pio_port:
-   0000                      28 	.ds 2
-   0002                      29 _pio_ctrl:
-   0002                      30 	.ds 2
-                             31 ;--------------------------------------------------------
-                             32 ; absolute external ram data
-                             33 ;--------------------------------------------------------
-                             34 	.area _DABS (ABS)
-                             35 ;--------------------------------------------------------
-                             36 ; global & static initialisations
-                             37 ;--------------------------------------------------------
-                             38 	.area _HOME
-                             39 	.area _GSINIT
-                             40 	.area _GSFINAL
-                             41 	.area _GSINIT
-                             42 ;--------------------------------------------------------
-                             43 ; Home
-                             44 ;--------------------------------------------------------
-                             45 	.area _HOME
-                             46 	.area _HOME
-                             47 ;--------------------------------------------------------
-                             48 ; code
-                             49 ;--------------------------------------------------------
-                             50 	.area _CODE
-                             51 ;pio.c:6: inline void _pio_data(int port, uint8_t data)
-                             52 ;	---------------------------------
-                             53 ; Function _pio_data
-                             54 ; ---------------------------------
-   0000                      55 __pio_data::
-                             56 ;pio.c:8: *(pio_port + port) = data;
-   0000 21 02 00      [10]   57 	ld	hl,#2
-   0003 39            [11]   58 	add	hl,sp
-   0004 FD 21r00r00   [14]   59 	ld	iy,#_pio_port
-   0008 FD 7E 00      [19]   60 	ld	a,0 (iy)
-   000B 86            [ 7]   61 	add	a, (hl)
-   000C 4F            [ 4]   62 	ld	c,a
-   000D FD 7E 01      [19]   63 	ld	a,1 (iy)
-   0010 23            [ 6]   64 	inc	hl
-   0011 8E            [ 7]   65 	adc	a, (hl)
-   0012 47            [ 4]   66 	ld	b,a
-   0013 21 04 00      [10]   67 	ld	hl, #4+0
-   0016 39            [11]   68 	add	hl, sp
-   0017 7E            [ 7]   69 	ld	a, (hl)
-   0018 02            [ 7]   70 	ld	(bc),a
-   0019 C9            [10]   71 	ret
-                             72 ;pio.c:11: inline void _pio_control(int port, uint8_t cmd)
-                             73 ;	---------------------------------
-                             74 ; Function _pio_control
-                             75 ; ---------------------------------
-   001A                      76 __pio_control::
-                             77 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   001A 21 02 00      [10]   78 	ld	hl,#2
-   001D 39            [11]   79 	add	hl,sp
-   001E FD 21r02r00   [14]   80 	ld	iy,#_pio_ctrl
-   0022 FD 7E 00      [19]   81 	ld	a,0 (iy)
-   0025 86            [ 7]   82 	add	a, (hl)
-   0026 4F            [ 4]   83 	ld	c,a
-   0027 FD 7E 01      [19]   84 	ld	a,1 (iy)
-   002A 23            [ 6]   85 	inc	hl
-   002B 8E            [ 7]   86 	adc	a, (hl)
-   002C 47            [ 4]   87 	ld	b,a
-   002D 21 04 00      [10]   88 	ld	hl, #4+0
-   0030 39            [11]   89 	add	hl, sp
-   0031 7E            [ 7]   90 	ld	a, (hl)
-   0032 02            [ 7]   91 	ld	(bc),a
-   0033 C9            [10]   92 	ret
-                             93 ;pio.c:16: void pio_set_mode(int port, int mode, uint8_t io)
-                             94 ;	---------------------------------
-                             95 ; Function pio_set_mode
-                             96 ; ---------------------------------
-   0034                      97 _pio_set_mode::
-                             98 ;pio.c:19: _pio_control(port, ((mode << 6) | 0x0F));
-   0034 21 04 00      [10]   99 	ld	hl, #4+0
-   0037 39            [11]  100 	add	hl, sp
-   0038 7E            [ 7]  101 	ld	a, (hl)
-   0039 0F            [ 4]  102 	rrca
-   003A 0F            [ 4]  103 	rrca
-   003B E6 C0         [ 7]  104 	and	a,#0xc0
-   003D F6 0F         [ 7]  105 	or	a, #0x0f
-   003F 4F            [ 4]  106 	ld	c,a
-   0040 D1            [10]  107 	pop	de
-   0041 E1            [10]  108 	pop	hl
-   0042 E5            [11]  109 	push	hl
-   0043 D5            [11]  110 	push	de
-                            111 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   0044 FD 2Ar02r00   [20]  112 	ld	iy,(_pio_ctrl)
-   0048 5D            [ 4]  113 	ld	e, l
-   0049 54            [ 4]  114 	ld	d, h
-   004A FD 19         [15]  115 	add	iy, de
-   004C FD 71 00      [19]  116 	ld	0 (iy), c
-                            117 ;pio.c:23: if (mode == PIO_MODE_BIT_IO) {
-   004F FD 21 04 00   [14]  118 	ld	iy,#4
-   0053 FD 39         [15]  119 	add	iy,sp
-   0055 FD 7E 00      [19]  120 	ld	a,0 (iy)
-   0058 D6 03         [ 7]  121 	sub	a, #0x03
-   005A C0            [11]  122 	ret	NZ
-   005B FD 7E 01      [19]  123 	ld	a,1 (iy)
-   005E B7            [ 4]  124 	or	a, a
-   005F C0            [11]  125 	ret	NZ
-                            126 ;pio.c:24: _pio_control(port, io);
-   0060 FD 21 06 00   [14]  127 	ld	iy,#6
-   0064 FD 39         [15]  128 	add	iy,sp
-   0066 FD 4E 00      [19]  129 	ld	c,0 (iy)
-                            130 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   0069 ED 5Br02r00   [20]  131 	ld	de,(_pio_ctrl)
-   006D 19            [11]  132 	add	hl,de
-   006E 71            [ 7]  133 	ld	(hl),c
-                            134 ;pio.c:24: _pio_control(port, io);
-   006F C9            [10]  135 	ret
-                            136 ;pio.c:28: void pio_set_interrupts(int port, int control)
-                            137 ;	---------------------------------
-                            138 ; Function pio_set_interrupts
-                            139 ; ---------------------------------
-   0070                     140 _pio_set_interrupts::
-                            141 ;pio.c:31: _pio_control(port, (control | 0x07));
-   0070 21 04 00      [10]  142 	ld	hl, #4+0
-   0073 39            [11]  143 	add	hl, sp
-   0074 7E            [ 7]  144 	ld	a, (hl)
-   0075 F6 07         [ 7]  145 	or	a, #0x07
-   0077 4F            [ 4]  146 	ld	c,a
-   0078 D1            [10]  147 	pop	de
-   0079 E1            [10]  148 	pop	hl
-   007A E5            [11]  149 	push	hl
-   007B D5            [11]  150 	push	de
-                            151 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   007C ED 5Br02r00   [20]  152 	ld	de,(_pio_ctrl)
-   0080 19            [11]  153 	add	hl,de
-   0081 71            [ 7]  154 	ld	(hl),c
-                            155 ;pio.c:31: _pio_control(port, (control | 0x07));
-   0082 C9            [10]  156 	ret
-                            157 ;pio.c:34: void pio_set_interrupts_mask(int port, int control, uint8_t mask)
-                            158 ;	---------------------------------
-                            159 ; Function pio_set_interrupts_mask
-                            160 ; ---------------------------------
-   0083                     161 _pio_set_interrupts_mask::
-                            162 ;pio.c:38: _pio_control(port, (control | 0x17));
-   0083 21 04 00      [10]  163 	ld	hl, #4+0
-   0086 39            [11]  164 	add	hl, sp
-   0087 7E            [ 7]  165 	ld	a, (hl)
-   0088 F6 17         [ 7]  166 	or	a, #0x17
-   008A 4F            [ 4]  167 	ld	c,a
-   008B D1            [10]  168 	pop	de
-   008C E1            [10]  169 	pop	hl
-   008D E5            [11]  170 	push	hl
-   008E D5            [11]  171 	push	de
-                            172 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   008F FD 2Ar02r00   [20]  173 	ld	iy,(_pio_ctrl)
-   0093 5D            [ 4]  174 	ld	e, l
-   0094 54            [ 4]  175 	ld	d, h
-   0095 FD 19         [15]  176 	add	iy, de
-   0097 FD 71 00      [19]  177 	ld	0 (iy), c
-                            178 ;pio.c:39: _pio_control(port, mask);
-   009A FD 21 06 00   [14]  179 	ld	iy,#6
-   009E FD 39         [15]  180 	add	iy,sp
-   00A0 FD 4E 00      [19]  181 	ld	c,0 (iy)
-                            182 ;pio.c:13: *(pio_ctrl + port) = cmd;
-   00A3 ED 5Br02r00   [20]  183 	ld	de,(_pio_ctrl)
-   00A7 19            [11]  184 	add	hl,de
-   00A8 71            [ 7]  185 	ld	(hl),c
-                            186 ;pio.c:39: _pio_control(port, mask);
-   00A9 C9            [10]  187 	ret
-                            188 	.area _CODE
-                            189 	.area _INITIALIZER
-   0000                     190 __xinit__pio_port:
-   0000 00 42               191 	.dw #0x4200
-   0002                     192 __xinit__pio_ctrl:
-   0002 02 42               193 	.dw #0x4202
-                            194 	.area _CABS (ABS)
diff --git a/sw/z80_tests/usart/build/sample.z80 b/sw/z80_tests/usart/build/sample.z80
deleted file mode 100644
index 965a0d8..0000000
--- a/sw/z80_tests/usart/build/sample.z80
+++ /dev/null
@@ -1,558 +0,0 @@
-;
-;  DZ80 V3.4.1 Z80 Disassembly of build/sample.bin
-;  2017/09/25 17:08
-;
-	org	0x0
-;
-X0000:	jp	X0100
-;
-	org	0x4
-;
-X0004:	rst	0x38
-X0005:	rst	0x38
-X0006:	rst	0x38
-;
-	org	0x8
-;
-	reti
-;
-X000a:	rst	0x38
-;
-	org	0xc
-;
-X000c:	rst	0x38
-X000d:	rst	0x38
-;
-	org	0x10
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x18
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x20
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x28
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x30
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x38
-;
-	reti
-;
-	rst	0x38
-;
-	org	0x100
-;
-X0100:	ld	sp,X0000
-	call	X0b15
-	call	X08b4
-	jp	X0804
-;
-	org	0x800
-;
-	ld	a,0x2
-	rst	8
-	ret
-;
-X0804:	ld	a,0x0
-	rst	8
-X0807:	halt
-;
-	jr	X0807
-;
-	ld	hl,X0002
-	add	hl,sp
-	ld	iy,X2000
-	ld	a,(iy+0x0)
-	add	a,(hl)
-	ld	c,a
-	ld	a,(iy+0x1)
-	inc	hl
-	adc	a,(hl)
-	ld	b,a
-	ld	hl,X0004
-	add	hl,sp
-	ld	a,(hl)
-	ld	(bc),a
-	ret
-;
-	ld	hl,X0002
-	add	hl,sp
-	ld	iy,X2002
-	ld	a,(iy+0x0)
-	add	a,(hl)
-	ld	c,a
-	ld	a,(iy+0x1)
-	inc	hl
-	adc	a,(hl)
-	ld	b,a
-	ld	hl,X0004
-	add	hl,sp
-	ld	a,(hl)
-	ld	(bc),a
-	ret
-;
-	ld	hl,X0004
-	add	hl,sp
-	ld	a,(hl)
-	rrca
-	rrca
-	and	0xc0
-	or	0xf
-	ld	c,a
-	pop	de
-	pop	hl
-	push	hl
-	push	de
-	ld	iy,(X2002)
-	ld	e,l
-	ld	d,h
-	add	iy,de
-	ld	(iy+0x0),c
-	ld	iy,X0004
-	add	iy,sp
-	ld	a,(iy+0x0)
-	sub	0x3
-	ret	nz
-	ld	a,(iy+0x1)
-	or	a
-	ret	nz
-	ld	iy,X0006
-	add	iy,sp
-	ld	c,(iy+0x0)
-	ld	de,(X2002)
-	add	hl,de
-	ld	(hl),c
-	ret
-;
-	ld	hl,X0004
-	add	hl,sp
-	ld	a,(hl)
-	or	0x7
-	ld	c,a
-	pop	de
-	pop	hl
-	push	hl
-	push	de
-	ld	de,(X2002)
-	add	hl,de
-	ld	(hl),c
-	ret
-;
-	ld	hl,X0004
-	add	hl,sp
-	ld	a,(hl)
-	or	0x17
-	ld	c,a
-	pop	de
-	pop	hl
-	push	hl
-	push	de
-	ld	iy,(X2002)
-	ld	e,l
-	ld	d,h
-	add	iy,de
-	ld	(iy+0x0),c
-	ld	iy,X0006
-	add	iy,sp
-	ld	c,(iy+0x0)
-	ld	de,(X2002)
-	add	hl,de
-	ld	(hl),c
-	ret
-;
-X08b4:	ld	hl,X000a
-	push	hl
-	ld	l,0x1
-	push	hl
-	ld	l,0x60
-	push	hl
-	call	X0a00
-	ld	hl,X0006
-	add	hl,sp
-	ld	sp,hl
-	ld	hl,X000d
-	push	hl
-	ld	hl,X08e2
-	push	hl
-	call	X0a49
-	pop	af
-	pop	af
-X08d3:	ld	hl,X0005
-	push	hl
-	ld	hl,X08f1
-	push	hl
-	call	X0a49
-	pop	af
-	pop	af
-	jr	X08d3
-;
-X08e2:	ld	c,b
-	ld	h,l
-	ld	l,h
-	ld	l,h
-	ld	l,a
-	inc	l
-	jr	nz,X0941
-	ld	l,a
-	ld	(hl),d
-	ld	l,h
-	ld	h,h
-	ld	hl,X000a
-X08f1:	ld	h,h
-	ld	l,a
-	ld	l,(hl)
-	ld	h,l
-	ld	a,(bc)
-	nop
-	ret
-;
-X08f8:	push	ix
-	ld	ix,X0000
-	add	ix,sp
-	ld	hl,(X2004)
-	ld	bc,X0004
-	add	hl,bc
-	ld	a,(hl)
-	or	0x80
-	ld	(hl),a
-	ld	hl,(X2004)
-	ld	c,(ix+0x4)
-	ld	(hl),c
-	ld	de,(X2004)
-	inc	de
-	ld	l,(ix+0x5)
-	ld	h,0x0
-	ld	a,(hl)
-	ld	(de),a
-	ld	hl,(X2004)
-	ld	bc,X0004
-	add	hl,bc
-	ld	a,(hl)
-	and	0x7f
-	ld	(hl),a
-	pop	ix
-	ret
-;
-X092c:	ld	hl,(X2004)
-	ld	bc,X0004
-	add	hl,bc
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	dec	a
-	jr	nz,X094b
-	ld	a,(iy+0x1)
-	or	a
-	jr	nz,X094b
-	ld	a,(hl)
-	or	0x10
-	ld	(hl),a
-	jr	X0962
-;
-X094b:	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	sub	0x2
-	jr	nz,X0962
-	ld	a,(iy+0x1)
-	or	a
-	jr	nz,X0962
-	ld	a,(hl)
-	and	0xef
-	ld	(hl),a
-X0962:	ld	hl,(X2004)
-	ld	bc,X0004
-	add	hl,bc
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	rlca
-	rlca
-	rlca
-	and	0xf8
-	and	0x8
-	ld	c,a
-	ld	a,(hl)
-	and	0xf7
-	or	c
-	ld	(hl),a
-	ret
-;
-X0980:	ld	bc,(X2004)
-	inc	bc
-	inc	bc
-	inc	bc
-	inc	bc
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	sub	0xa
-	jr	nz,X099f
-	ld	a,(iy+0x1)
-	or	a
-	jr	nz,X099f
-	ld	a,0x1
-	jr	X09a0
-;
-X099f:	xor	a
-X09a0:	xor	0x1
-	add	a,a
-	add	a,a
-	and	0x4
-	ld	l,a
-	ld	a,(bc)
-	and	0xfb
-	or	l
-	ld	(bc),a
-	ret
-;
-	ld	hl,(X2004)
-	ld	bc,X0004
-	add	hl,bc
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	and	0x3
-	ld	c,a
-	ld	a,(hl)
-	and	0xfc
-	or	c
-	ld	(hl),a
-	ret
-;
-X09c6:	ld	hl,(X2004)
-	ld	bc,X000c
-	add	hl,bc
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	and	0x1
-	ld	c,a
-	ld	a,(hl)
-	and	0xfe
-	or	c
-	ld	(hl),a
-	ld	hl,(X2004)
-	ld	bc,X0005
-	add	hl,bc
-	ld	a,(iy+0x0)
-	sub	0x3
-	jr	nz,X09f6
-	ld	a,(iy+0x1)
-	or	a
-	jr	nz,X09f6
-	ld	a,0x1
-	jr	X09f7
-;
-X09f6:	xor	a
-X09f7:	and	0x1
-	ld	c,a
-	ld	a,(hl)
-	and	0xfe
-	or	c
-	ld	(hl),a
-	ret
-;
-X0a00:	pop	bc
-	pop	hl
-	push	hl
-	push	bc
-	push	hl
-	call	X08f8
-	pop	af
-	ld	hl,X0004
-	add	hl,sp
-	ld	c,(hl)
-	inc	hl
-	ld	b,(hl)
-	push	bc
-	call	X092c
-	pop	af
-	ld	hl,X0006
-	add	hl,sp
-	ld	c,(hl)
-	inc	hl
-	ld	b,(hl)
-	push	bc
-	call	X0980
-	ld	hl,X0000
-	ex	(sp),hl
-	call	X09c6
-	pop	af
-	ret
-;
-	ld	hl,(X2004)
-	ld	iy,X0002
-	add	iy,sp
-	ld	a,(iy+0x0)
-	ld	(hl),a
-X0a36:	ld	hl,(X2004)
-	ld	bc,X000d
-	add	hl,bc
-	ld	a,(hl)
-	rlca
-	rlca
-	rlca
-	jr	nc,X0a36
-	ret
-;
-	ld	hl,(X2004)
-	ld	l,(hl)
-	ret
-;
-X0a49:	push	ix
-	ld	ix,X0000
-	add	ix,sp
-	push	af
-	ld	a,(ix+0x4)
-	ld	(ix+0xfe),a
-	ld	a,(ix+0x5)
-	ld	(ix+0xff),a
-	ld	c,(ix+0x6)
-	ld	b,(ix+0x7)
-X0a64:	ld	e,c
-	ld	d,b
-	dec	bc
-	ld	a,d
-	or	e
-	jr	z,X0a89
-	ld	de,(X2004)
-	pop	hl
-	push	hl
-	ld	a,(hl)
-	inc	(ix+0xfe)
-	jr	nz,X0a7a
-	inc	(ix+0xff)
-X0a7a:	ld	(de),a
-X0a7b:	ld	hl,(X2004)
-	ld	de,X000d
-	add	hl,de
-	ld	a,(hl)
-	rlca
-	rlca
-	jr	nc,X0a64
-	jr	X0a7b
-;
-X0a89:	ld	l,c
-	ld	h,b
-	ld	sp,ix
-	pop	ix
-	ret
-;
-	push	ix
-	ld	ix,X0000
-	add	ix,sp
-	ld	hl,Xfffa
-	add	hl,sp
-	ld	sp,hl
-	ld	a,(ix+0x4)
-	ld	(ix+0xfa),a
-	ld	a,(ix+0x5)
-	ld	(ix+0xfb),a
-	ld	c,(ix+0x6)
-	ld	b,(ix+0x7)
-	ld	(ix+0xfc),0x0
-	ld	(ix+0xfd),0x0
-X0ab7:	ld	e,c
-	ld	d,b
-	dec	bc
-	ld	a,d
-	or	e
-	jr	z,X0b06
-	ld	hl,(X2004)
-	ld	e,(hl)
-	pop	hl
-	push	hl
-	ld	(hl),e
-	inc	(ix+0xfa)
-	jr	nz,X0acd
-	inc	(ix+0xfb)
-X0acd:	ld	de,(X2004)
-	ld	hl,X000d
-	add	hl,de
-	ld	(ix+0xfe),l
-	ld	(ix+0xff),h
-	ld	l,(ix+0xfe)
-	ld	h,(ix+0xff)
-	ld	a,(hl)
-	rrca
-	rrca
-	rrca
-	and	0x1
-	jr	nz,X0af6
-	ld	l,(ix+0xfe)
-	ld	h,(ix+0xff)
-	ld	a,(hl)
-	rrca
-	rrca
-	and	0x1
-	jr	z,X0afc
-X0af6:	pop	hl
-	push	hl
-	dec	hl
-	ex	(sp),hl
-	jr	X0ab7
-;
-X0afc:	inc	(ix+0xfc)
-	jr	nz,X0ab7
-	inc	(ix+0xfd)
-	jr	X0ab7
-;
-X0b06:	pop	bc
-	pop	hl
-	push	hl
-	push	bc
-	ld	sp,ix
-	pop	ix
-	ret
-;
-X0b0f:	nop
-	ld	b,d
-	ld	(bc),a
-	ld	b,d
-	nop
-	ld	b,b
-X0b15:	ld	bc,X0006
-	ld	a,b
-	or	c
-	jr	z,X0b24
-	ld	de,X2000
-	ld	hl,X0b0f
-	ldir
-X0b24:	ret
-;
-	rst	0x38
-;
-;	Miscellaneous equates
-;
-;  These are addresses referenced in the code but
-;  which are in the middle of a multibyte instruction
-;  or are addresses outside the initialized space
-;
-X0002	equ	0x2
-X2002	equ	0x2002
-X2004	equ	0x2004
-Xfffa	equ	0xfffa
-;
-	end
-;
-
diff --git a/sw/z80_tests/usart/main.c b/sw/z80_tests/usart/main.c
deleted file mode 100644
index d2e1d8e..0000000
--- a/sw/z80_tests/usart/main.c
+++ /dev/null
@@ -1,11 +0,0 @@
-#include "usart.h"
-
-void main(void)
-{
-    usart_init(USART_BAUDRATE_1200, USART_PARITY_EVEN, USART_STOP_BITS_1);
-    usart_write("Hello, World!\n", 13);
-
-    while(1) {
-        usart_write("done\n", 5);
-    }
-}
diff --git a/sw/z80_tests/usart/usart.c b/sw/z80_tests/usart/usart.c
deleted file mode 120000
index 2927470..0000000
--- a/sw/z80_tests/usart/usart.c
+++ /dev/null
@@ -1 +0,0 @@
-../../z80/kernel/drivers/usart.c
\ No newline at end of file
diff --git a/sw/z80_tests/usart/usart.h b/sw/z80_tests/usart/usart.h
deleted file mode 120000
index 84ee24d..0000000
--- a/sw/z80_tests/usart/usart.h
+++ /dev/null
@@ -1 +0,0 @@
-../../z80/kernel/include/drivers/usart.h
\ No newline at end of file