Z80 Assembly programming for the Elan Enterprise 128

The Enterprise 128 is an 8 bit Z80 system, it's comparable to the Amstrad CPC,however it has more advanced Memory Mapping which allows more flexible bank switching, and more advanced graphics Like the CPC screen it can function at 320x200 at 4 colors, and you can halve the resolution to get 160x200 with 16 colors... unlike the CPC, there is a 256 color mode of 80x200 All these modes can be 'half resolution' of 100 vertical pixels

The Basic Enterprise has 64k, but we'll be focusing on the 256k version Cpu 4 mhz Z80 Ram 64k / 128k Resolution 320x200 4 color 160x200 16 color 80x200 256 color Sound chip 3 Channel sound (non AY)

Useful Documents

EXOS20_technical_information.pdf

ChibiAkumas Tutorials

Memory Banks

We can ask the OS for memory, and then use it for whatever we want... if we don't need it any more, we can tell the OS to take it back! This is how we get a free VRAM bank... we ask for memory banks, until we get one >=FC (a 64k internal bank)... This may take a while, as the OS gives us the low numbered banks first... but once we get one, we can just free up all the ones we didn't really want! We use RST 6 to do an EXOS call... and command 24 to request a segment, and 25 to give it back!

If we don't need the OS, we can just use the memory ourselves without asking... But if we want it to do Disk reading or other things for us, we need to play nice! It all depends on how you plan to use the system, and how worried you are about compatibility.

Screen Memory

The Enterprise screen memory location and layout is defined by a LPT block

Enterprise Screen bit layout

The pixel bits are in different orders, depending on screen mode.
In the chart below: Numbers are the bit number, A-Z are the pixels contained in the byte.

Keyboard/Joystick

Reading from the keyboard on the enterprise is easy.
There are 10 rows, from 0-9, we just send the number of the row we want to port &B5, we then read in from port &B5 to get the status of the keys in that row.

Reading the Joystick in is also done from port &B5 , however to select the row we use port &B6.

General Ports on the Enterprise (&80-&83=NICK)

Sound ports on the Enterprise (DAVE)

For full details See page 50: EXOS20_technical_information.pdf

EXOS Variables

Use with EXOS call 16 (set C to var number)

Enterprise Programming Tutorials:

General Z80 Assembly Tutorials:

Hello World

Here's my Hello World example. I couldn't find one, so I had to write it! It uses the operating system to access the screen and keyboard. This code was tested using WinApe - which is a CPC emulator, but it can compile ASM program code just fine
Download this from the sourcecode link at the top of this page!

write "..\RelEnt\program.com" ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;            Hello World ; ;    Show a hello world message, then read a key ;    From the keyboard and show it. ; ;    Screen and keyboard ops use Enterprise OS calls ;    by opening 'stream' devices to the Keyboard and ;    screen ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ORG &00F0     DB0,5               ;type 5 - Binary Program     DW FileEnd-FileStart       ;File length     DB 0,0,0,0,0,0,0,0,0,0,0,0 ;Spacer ; org &0100 FileStart:     LD SP,&100    ;set the Stack to a safe place     di     ld c,MODE_VID        ;Set text mode     ld d,0     call ENT_Writevar     ld c,COLR_VID        ;Set 2 color     ld d,0     call ENT_Writevar     ld c,X_SIZ_VID        ; 40 Chars Wide     ld d,40     call ENT_Writevar     ld c,Y_SIZ_VID        ;24 chars tall     ld d,24     call ENT_Writevar     ld de,ENT_Screenname     ;Open Screen as stream 10     ld a,10     call ENT_OpenStream         ;Display the just opened screen     ld a,10    ; A channel number (1..255)     ld b,1    ; B @@DISP (=1) (special function code)     ld c,1    ; C 1st row in page to display (1..size)     ld d,24  ; D number of rows to display (1..27)     ld e,1  ; E row on screen where first row should appear (1..27)     call ENT_SpecialFunc     ld de,ENT_Keboardname    ; Open the keyboard as stream 11     ld a,11     call ENT_OpenStream ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;            INIT Done ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;     ld hl,Message     call PrintString    ;Print Hello world message     call NewLine             call WaitChar        ;Wait for a keypress     push af         ld hl,Message2    ;Print 'You Pressed' message         call PrintString     pop af     call PrintChar        ;print the char the user pressed     call NewLine     di     halt    ;stop execution - I've not figured out how to return to basic! Message: db 'Hello World!',255 Message2: db 'Key Pressed:',255 PrintString:     ld a,(hl)     cp 255     ret z     inc hl     call PrintChar jr PrintString ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;        Functions for controling EXOS ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; MODE_VID  equ 22    ;Enterprise OS variable numbers COLR_VID  equ 23 X_SIZ_VID equ 24 Y_SIZ_VID equ 25     ENT_OpenStream:     ;Open stream A from device string DE     ;DE should point to a string like...  db 6,'VIDEO;'  or db 9,'KEYBOARD;' (replace ; with a colon)     rst 6     db 1     ;open stream ret WaitChar:     push de     push hl     push bc         ld a,11         rst 6         db 5     ;read from channel - result in b         ld a,b     pop bc     pop hl     pop de ret PrintChar:     push de     push hl     push bc         ld b,a         ld a,10         rst 6         db 7     ;write to channel a     pop bc     pop hl     pop de ret NewLine:     ld a,13     call PrintChar     ld a,10     call PrintChar ret ENT_readvar:        ;readvar C from enterprise OS     ld b,0     rst 6     db 16 ret ENT_Writevar:        ;WriteVar C=D to Enterprise OS     ld b,1     rst 6     db 16 ret ENT_SpecialFunc:    ;Special Function (for displaying screen)     rst 6     db 11 ret ;Device names db [length],'name;' ENT_Screenname: db 6,'VIDEO:' ENT_Keboardname: db 9,'KEYBOARD:' ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; FileEnd:

Starting the program: The program will show hello world, then pause for a keypress