c64 games converted to plus/4?

[CrazyBoss]

Hi

 

I remember I saw a guy in Hungary, converted a lot of C64 games to run on the Commodore plus/4

 

I should be a hard task, since the cpu and graphics chip are not the same. But it seems he managed to do it.

 

I convert to/from ColecoVision and Memotech Mtx but those have same CPU and VDP (video chip) and that is hard enough

 

Cant imagine to convert to a complete other CPU and Graphics chip.

 

I just want to know, just for interests - I do not have any plans to convert Commodore games. (have more than enough with my z80 projects)

 

[+save2600]

Neat project, but can't imagine there being enough Plus/4 users here or out by you to make all the trouble worth it.

 

I'd rather see people devoting their smarts and time toward fixing all the crap C64 downloads that don't work when you try to run them. On_your_C64.

[+OLD CS1]

Neat project, but can't imagine there being enough Plus/4 users here or out by you to make all the trouble worth it.

 

I'd rather see people devoting their smarts and time toward fixing all the crap C64 downloads that don't work when you try to run them. On_your_C64.

 

You would be surprised... I have found those guys are CRA-ZY.

[+eebuckeye]

Biggest problem I have found is most games (like 90%) are PAL only...

[TMR]

I remember I saw a guy in Hungary, converted a lot of C64 games to run on the Commodore plus/4

 

I should be a hard task, since the cpu and graphics chip are not the same. But it seems he managed to do it.

It's really not as difficult as you might think; the part numbers might be different, but both machines are built around a 6502 variant CPU so platform-agnostic code such as game logic will port directly over (i took the code from the C16 version of Kikstart and converted it to the C64 a while back). And, apart from the lack of hardware sprites at the Plus/4's end, the way that the screen is formatted for both character- and bitmap-based modes is the same too; there's also a bit of extra processing power to get software sprites going when the original game used hardware.

 

Even some of the register "features" abused by demos will translate as well, just with slightly different results; messing with the vertical smooth scroll can do all manner of interesting stuff!

 

Neat project, but can't imagine there being enough Plus/4 users here or out by you to make all the trouble worth it.

It's a programmer thing; most of the time we'll take something on for the challenge, so having other people enjoying the work afterwards is just gravy really; i've been following the blog of a guy who takes Spectrum games and converts them to the TRS-80 for example, that's a metric bucketload of work done for "just because" reasons. There is a quite large following for the 264 series out there though, with a good forum, regular but not frequent releases and some decent emulators like YAPE too.

 

I'd rather see people devoting their smarts and time toward fixing all the crap C64 downloads that don't work when you try to run them. On_your_C64.

For the most part they're not "crap" and do actually run on a real C64, but it needs to be a PAL machine because the bulk of what is online was cracked and later archived by European cracking groups so even the games originally developed in NTSC territories tend to be deprotected from a PAL original. That doesn't mean there aren't NTSC versions about and jewel cracking groups like Nostalgia tend to aim for PAL/NTSC as standard, but a lot of stuff just hasn't been done at the moment and it's a matter of trawling through the CSDb for a (hopefully) 100% working fix.

[+save2600]

I get it TMR - and beggars can't be choosers. Appreciate the explanation. Just gets irritating when you're searching through some of these sites, only to find 10 different versions of the same game, all with different and often cryptic suffices, acronyms, file types, compression schemes, etc., only to find that (as eebuckeye mentioned) 90+% don't work on your system for some reason or another - usually region related I guess.

 

Didn't mean to derail the OP's thread.

[SSG]

I wish my plus/4 worked........

[carlsson]

Yes indeed, the 6510 and 7501/8501 are software compatible so in that respect it is no different than if you port code from a Zilog Z80 to a NEC D780C. Even I managed to port my music player to Plus/4 with very little trouble, and the differences lied in how the sound part of the TED chip works, rather than the assembly code to run the player.

[TMR]

I get it TMR - and beggars can't be choosers. Appreciate the explanation. Just gets irritating when you're searching through some of these sites, only to find 10 different versions of the same game, all with different and often cryptic suffices, acronyms, file types, compression schemes, etc., only to find that (as eebuckeye mentioned) 90+% don't work on your system for some reason or another - usually region related I guess.

It'll almost always be region-related yes, PAL C64s have more processing time per frame so anything getting close to the wire on that front is immediately going to be a complete pig to NTSC fix for example and there are some older disk fastloading schemes which are sensitive to that timing as well. A lot of the cracks online were done "back in the day" when speed was important too, everybody was vying for the first release of a specific title and an NTSC fix would've been low on the list of priorities because of that. There are broken cracks on the CSDb because their intention is to archive all the things as part of the scene's history, but those breakages tend to manifest themselves as corrupt level data or embedded protection checks that were missed by the cracker, usually they'll work for a bit before falling over.

 

The suffixes aren't particularly cryptic though, something like +4DFHR translates as four trainers, Documentation included, Fixed for PAL/NTSC, Highscore saver, and RAM expansion support (usually the levels will be cached to RAM to cut down on loading). Looking for either a version by an NTSC group or an F in the suffix of a PAL release isn't guaranteed to find something that's 100% working, but will improve the odds drastically.

 

Didn't mean to derail the OP's thread.

It's sort of relevant, understanding what PAL/NTSC looks like from a programming standpoint helps with getting your head around how easy/hard porting would be. =-)

[TMR]

Even I managed to port my music player to Plus/4 with very little trouble, and the differences lied in how the sound part of the TED chip works, rather than the assembly code to run the player.

Same here when i ported my game Reaxion, i reworked the graphical side of things to fit but the game logic is pretty much identical to the C64 code even down to the obscenities in the labels!

[carlsson]

Now that I think about it, back when I made my first minigames in 2002, for some reason I was still using my Amiga as development platform. I didn't have any reasonable VIC or C64 emulator, so the first prototype of my Othello game was assembled to run on whatever Plus/4 emulator I got on the Amiga! Later on in development though, I targeted it to VIC-20.

[JamesD]

You'd probably be better off posting here:
http://plus4world.com/

As other's said, the C64 and Plus/4 have variants of the 6502.
Several of the graphics modes are similar if I remember right.
If a game doesn't use hardware sprites porting shouldn't be too bad.
Some games even run faster on the Plus/4. Elite is a good example. The Asteroids emulator is another.