Monday, October 02, 2006

XeO3: C64

I'm having fun with the C64 just now while Luca gathers together some sprites for me to use, but I've hit my first snag.... The MCM on the plus4 uses differnt bits than the C64! Damn. So, I've done a bit flipper to swap bits $01 and $10. This lets the colour RAM on the C64 do the bright colour (since in MCM on the C64 you only have a choice of 8), and the 2 full colour registers then make up the rest... This will work fine for the game graphics, but......... The panel has some HiRes graphics in it...Damn, damn.....

So looks like I'll have to do a character index and tell it the ones I WANT to swap...bugger. However, once thats done it should just be a matter of importing Plus4 graphics and using them directly! Initally I'll do a port routine for the Plus4 sprites as well, then I'll get them resized. The C64 sprites are 24x21 (or 12x21 in MCM), while the Plus4 ones are 16x16 so there quite a bit of extra space there! The reason for the odd sizes is simpky that it lets the C64 have a sprite every 64 bytes, making 256 in a VIC bank.

I think I can get the whole thing up and running (without sprites) pretty quickly, then I'll need to get a multiplexor going... and then that "should" be it! :)

(in theory....) Imagine doing a "dual" retro release!! How cool is that!!! Now... if only I could persuade Russell (Kay - Lemmings PC programmer) to write the spectrum one...Mmmmm.... That WOULD be a complete rewrite though...


luca said...

Spectrum? Spectrum? Who said Spectrum? :O

Mike said...


Just before leaving to go to Boston a few months back, I was showing Russell the progress we'd made and he got all excited and started playing with Spectrum stuff again. He's actually written a spectrum game before so knows Z80+machine quite well. (^Zone+Trooper$&pub=^Game+Busters$)

It would be soooo cool to be able to do a multiplatform release of a game, it hasn't happened on these machines for 15 years! :D

But I wouldn't hold you're breath - he has less time than I do!

Anonymous said...

If somebody does a Spectrum port, what about an Amstrad (or even MSX) port then? :) Many Amstrad games have Spectrum graphics which is a shame compared to what they really could do but it's better then nothing. And it's Z80, too, so not everything has to be rewritten from scratch once a Spectrum port ist done.

And there are some Atari 8Bit freaks around, too :) Fortunately, that's 6502 again :D

If you really really want a multiplatform release, I think it's possible. Though, in a very egoistic way I care most about the plus/4 version to be finished ;)


Mike said...

Well, like I said...I doubt its gonna happen. I could do that as well... but since its a rewrite, thats probably taking it a bit far; the only thing that would survive would be the paths... everything else would have to be redone.

But, one the source is released, other folk can do it if the like.... or port it to another 6502 machine.

Anonymous said...

I was searching for a site about some Polish coders converting IK+ from C64 to Atari 8bit. Finally, I found it but more interestingly, I ran across lots of cool Atari 8bit sites. I knew it was a very popular machine in Poland but I didn't know that there's still such a strong scene.

This one should be of special interest to you, even if it's in Polish. It does have several screen shots :)

Just like on plus/4 there have been some "break throughs" on the Atari 8bit machines recently (last couple of years, that is ;) ). New techniques, hardware tricks etc...

As I read in some forums not many games have been released, though, since it's quite a difference between a demo and a game. If it's ok with you I'll post a link on a polish forum to the XeO3 site. It might get some ppl interested in Your game.


Mike said...

Cool! Lemmings has been on everything! :)

Sure, post away.... You can mention that the 6502 source will be released along with the game.