| |
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? |
|
| |
wil
Registered: Jan 2019
Posts: 63 |
If the I/O area is set to be visible via the MMU, the layout of VIC registers, SID registers, screen (at $400) and color ram ($d800) are identical to the C64, so it should be possible to write a program that starts for example at $1c0d and if executed on the C64, transfers the program there first. Of course, this requires the user to load the program with ",8" on the C64; otherwise, the Basic Sysline is not at $801.
When using Sprites while having the Kernal active, the C128 needs to be told to get its fingers off the sprite registers (by clearing bit 1 of $A04). Note that the user could also have used the GRAPHICS command before loading the program, then the start adress is even at $4001. |
| |
Count Zero
Registered: Jan 2003
Posts: 1940 |
BASIC programs can be made "multi platform" more or less easily. Likely in the BBS/terminal field such 64/128 cross platform support can be found.
I remember some filebrowser source which had vc20/c16/c64/c128 code included but that produced several binaries. |
| |
Jammer
Registered: Nov 2002
Posts: 1336 |
I'm mostly concerned with asm code run via sysline. |
| |
Krill
Registered: Apr 2002
Posts: 2981 |
X-Y problem time! =)
C-128 programs usually run via the boot block. You insert the disk, power up or reset the computer, program boots.
As such, you wouldn't really have to have the very same program run natively on both C-64 and C-128. It'd be an academic exercise with little practical relevance.
So, what do you actually want to achieve? |
| |
Jammer
Registered: Nov 2002
Posts: 1336 |
One-filed C64 fps game which runs at slightly better framerate if it detects C128 😃 |
| |
chatGPZ
Registered: Dec 2001
Posts: 11390 |
for that, just always do the d030 switching in the border. no need to detect anything :) (and then it will automagically also work with other turbos that use that bit) |
| |
Krill
Registered: Apr 2002
Posts: 2981 |
Quoting JammerOne-filed C64 fps game which runs at slightly better framerate if it detects C128 😃 So not running in native C-128 mode? |
| |
chatGPZ
Registered: Dec 2001
Posts: 11390 |
BTW, crafting a file that would load and start in c128 mode instead of c64 mode (and still works in c64 mode) is probably possible too (not trivial, and you'll be forced to load ,8 only in one of the modes). I doubt it makes sense for the sort of thing you have in mind though :) |
| |
Krill
Registered: Apr 2002
Posts: 2981 |
Quoting chatGPZand you'll be forced to load ,8 only in one of the modes) Could be quite possible to craft an ",8,1" (or BLOAD) autorun program that would work in both C-64 and native C-128 modes.
But then again, quite pointless when there is a boot block (plus not a sensible notion of "one-filer" on C-128). |
| |
chatGPZ
Registered: Dec 2001
Posts: 11390 |
oh yeah, with autorun. sure. even more messier :=) |
... 35 posts hidden. Click here to view all posts....
|
| Previous - 1 | 2 | 3 | 4 | 5 - Next |
