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Jammer
Registered: Nov 2002
Posts: 1336 |
C64/C128 combo program compilation
Question might turn out plainly stupid so bear with me but I'm total noob on C128.
Can C64 program be compiled to run both on C64 and C128 in its native 128k mode if it has appropriate branches in code? Or it's always two separate tailored builds?
I've already learnt that C128 program startup is either $1C01 or $4001 but if C128 startup was embedded at the right spot, would it still launch? |
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Jammer
Registered: Nov 2002
Posts: 1336 |
Thanks, guys, for the heads up! <3 Is it also same problem with SuperCPU and other accelerators? |
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chatGPZ
Registered: Dec 2001
Posts: 11390 |
No, the others don't result in that kind of garbage display. SCPU is an entirely different beast though :) |
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zzarko
Registered: Feb 2003
Posts: 77 |
3rd place at Revision 2024 Wild category:
https://www.pouet.net/prod.php?which=96567
The same binary (although with some caveats) works on C64, MSDOS, Linux, SNES, NDS, Gameboy, Gamecube, can be unpacked as a ZIP file (then it contains its complete source) and can be openbed as PDF. For any of these, just change the extension.
So I would guess there is definitely a way to make one binary that runs on C64 and C128 without modifications (I am not saying that I can make one!). |
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Martin Piper
Registered: Nov 2007
Posts: 726 |
Quote: 3rd place at Revision 2024 Wild category:
https://www.pouet.net/prod.php?which=96567
The same binary (although with some caveats) works on C64, MSDOS, Linux, SNES, NDS, Gameboy, Gamecube, can be unpacked as a ZIP file (then it contains its complete source) and can be openbed as PDF. For any of these, just change the extension.
So I would guess there is definitely a way to make one binary that runs on C64 and C128 without modifications (I am not saying that I can make one!).
This is nice. As long as the prg is loaded with ,8 and not ,8,1 then it would be relatively easy to make a prg that detects if it is running in C64 or C128. |
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oziphantom
Registered: Oct 2014
Posts: 490 |
I guess you could use BASIC to detect which machine you are on, or maybe which version of BASIC you are running?
Set the BASIC error vector to something custom and then try and run a BASIC 7.0 command, if it fails you know you are BASIC 2, if it passes you know you are BASIC 7 and hence then know were the asm code starts. Both the 64 and 128 have the BASIC error vector at $300/1.
However you then still have the issue that your code has to handle being in two different memory locations, but I guess at that point you could jump to a known address at the end of code on a 128 that then copies the main code down to 0801 or wherever you want to start, then apply your patches and then jump to it. |
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aeeben
Registered: May 2002
Posts: 44 |
@Jammer, if this is for the project I think it is, why not do a native version for C-128 in the VDC 80 column display, then you can run all calculations at 2 kHz :) [Ouch, actually, writing to VDC is probably too slow...]
Almost related bits from VIC 20 world: I used this loader in Hare Basic - it does autostart on both VIC 20 and C-64, and loads&runs either the file "A000" or "C000". As a little bonus, it can be also loaded with ",8" on both machines, but then obviously requires a RUN.
(Inspired by Mike's VIC 20 memory-configuration-independent-autostart code on Denial forum.)
processor 6502
SETLFS equ $ffba
SETNAM equ $ffbd
LOAD equ $ffd5
RESTOR equ $ff8a
CHROUT equ $ffd2
CLRCHN equ $ffcc
SCREEN equ $ffed
; C-64 / VIC 20 Autostart
;
; load"*",8 or load"boot",8 (and run)
; load"*",8,1 or load"boot",8,1 (autostart)
start equ $02a7
org start
incbin "autostart-basic.bin" ; 2024 syspeek(44)*256+peek(43)+21
basic
ldy #bootend-start-1
.1
lda ($2b),y
sta start,y
dey
bne .1
jmp boot
boot
jsr SCREEN ; detect C-64 or VIC 20 by number of rows
cpy #$19
beq .c64
.vic20
jsr $e45b ; restore basic vectors (VIC 20)
lda #$a0
sta start_+2 ; modify start address to $a000
lda #$41
sta filename ; modify filename to "A000"
bne .load
.c64
jsr $e453 ; restore basic vectors (C-64)
.load
ldx #<filename ; set up filename
ldy #>filename
lda #$04
jsr SETNAM
lda #$01 ; set up file
sta $9d
ldx $ba
tay
jsr SETLFS
lda #$00 ; load and execute
jsr LOAD
start_
jmp $c000
filename
dc.b "C000"
bootend
org $0300
dc.w boot
dc.w boot
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oziphantom
Registered: Oct 2014
Posts: 490 |
yeah but the VIC-20 and C64 have the same version of BASIC with the same vectors and ROM in the same place. The 128 is not a slightly bigger C64 it's a smaller Amiga.
Putting that code on a 128 will trash
02a2-02ae 674-686 Kernal RAM
02a2-02ae Bank Peek Subroutine
02af-02bd Bank Poke Subroutine
02be-02cc Bank Compare Subroutine
02cd-02e2 JSR to Another Bank
02e3-02fb JMP to Another Bank
02fc-02fd Function Execute Hook [4c78]
which will cause crashes |
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chatGPZ
Registered: Dec 2001
Posts: 11390 |
Quote:The 128 is not a slightly bigger C64 it's a smaller Amiga.
It has more in common with a Spectrum than with an Amiga though :D |
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Jammer
Registered: Nov 2002
Posts: 1336 |
Amiga is a direct descendent of Atari, deal with it ;) |
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MagerValp
Registered: Dec 2001
Posts: 1078 |
Writing a big basic program with branching logic to detect C128 or C64 is easy enough, but I'd prefer something compact even if a bit hacky. The best I could come up with on my lunch break is SYS(PEEK(57532)-219)*256+30.
Sample project here: https://github.com/MagerValp/C128-C64-PIBS |
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