10 replies to this topic

[Miqorz]

Okay I have a dream to make a 7800 1942 clone homebrew but I don't know anything about programming for the 7800!

I'd REALLY like to make this dream a reality and I am sure the 7800 community would like a homebrew.. so anything would be appreciated.

[EricBall]

Check out Dan Boris's 7800 page to start. There are other pages around with some more tidbits of info, but I should warn you that there is far less info & sample code available than for the 2600.

I've started fiddling with the 7800 (via emulator) myself, though I haven't gotten beyond the blank screen stage. (No z26.log either, sniff.) My current plan is to disassemble (my own disassembler, but Disasm now handles 7800) a couple of games and try to figure out what I've done wrong.

[Heaven/TQA]

Eric,

it's easier than you think... feel free to have a look into my 7800 homebrew Senso 7800 dx

http://www.s-direktn...nadj/a7800.html

cheers, karolj

[DanBoris]

Miqorz said:

Okay I have a dream to make a 7800 1942 clone homebrew but I don't know anything about programming for the 7800!

I'd REALLY like to make this dream a reality and I am sure the 7800 community would like a homebrew.. so anything would be appreciated.

1942 would be a good fit for the 7800 hardware. There are a few people on this board who have done some 7800 programming, so dive in and feel free to ask questions as you go along.

Dan

[EricBall]

Dan, would it be possible to get the debug version of V7800 (or a Win32 MESS/7800 debug version)? My current test application (working on a demo which uses overlapping tiles) crashes on startup. (I've tried your demo, it does the same thing....) Just some assurance that the BIOS gets the checksum right would be nice.

And a question - how accurate/reliable is V7800 or MESS when it comes to DMA timing? I have a feeling that my demo is pushing the limits of what Maria will do in 456 cycles. Or should I budget for both a real 7800 and Chad's Cuttle78?

[DanBoris]

You best bet would be to compile a debug version of MESS and use that. The emulation is better the V7800 and it has a much better debugger. You may be able to find a pre-compiled debug MESS.

The emulation in MESS will allow you to freely pass the DMA cycle limit and show no ill effects, so it's definitly not good for final testing. If you plan to develop homebrew games for the 7800 you simply can't avoid eventually testing it on the real hardware.

Dan

[EricBall]

Figured out the problem, I forgot a $ for the LDA # STA CTRL to start DMA. I'm now getting a display, and it looks like what I'm expecting (I think...)

Unfortunately, I'm not in a position to recompile MESS for myself (thus my request for a pre-compiled debug binary).

Thanks for the heads up on the DMA timing. I thought that might be true. One of the documents gives some timing values, but I'm not sure whether two byte indirect requires 9 or 12 cycles per character (9 makes sense to me, 3x1 for the character & 3x2 for each of the graphic bytes). Well, maybe I'll just make something which looks cool on an emulator, even if it can't work on the actual hardware.

[shep]

Word of advice! I do not care how smart you are! Don't go in this thinking it won't be difficult, too many people try to learn to program for these consoles thinking like that and it ends up hurting them. Other than that goodluck!

[Mitch]

If you need a beta tester for a 7800 game let me know. I can test on a real 7800 for you.

Mitch

[Miqorz]

Mitch said:

If you need a beta tester for a 7800 game let me know. I can test on a real 7800 for you.

Mitch

Works for me..

Once I get a little of the game done you'll be one of the first to know.

Thanks,

Mike