Search found 2301 matches

by TmEE co.(TM)
Tue Jul 31, 2018 12:49 pm
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 11
Views: 641

Re: Cart Design Questions

You'll be up for plenty of manual work. I have worked with pulls in past and you absolutely have to verify them all, out of 700 chips, around 100 were dead or damaged (i.e parts of it not programmable etc.). Also pins way not be in the best shape, causing difficulties when soldering. Those stocks ca...
by TmEE co.(TM)
Fri Jul 27, 2018 2:03 am
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 11
Views: 641

Re: Cart Design Questions

EPROMs have not been produced for years, if you're lucky you can get new-old-stock but you're very likely to get pulls. Your only option is 3.3V parts, having the level shifters and then exclusively using 3.3V parts will cost less than trying to get 5V stuff together. There's far more options and mo...
by TmEE co.(TM)
Tue Jul 24, 2018 4:24 pm
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 11
Views: 641

Re: Cart Design Questions

That EPROM will work but availability might be limited if you intend to make lot of cartridges. They are also likely to be pulls rather than new parts. To save a looooot of time make sure the parts you order are erased before hand. It takes half an hour at least to erase an EPROM. If the MCU has 5V ...
by TmEE co.(TM)
Tue Jul 17, 2018 8:42 am
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 11
Views: 641

Re: Cart Design Questions

You need full level conversion, resistors aren't going to do anything but current limiting. For single direction stuff you could get away with voltage dividers but signal edges will get poor. For bidirectional signals you'll definitely want actual chips doing the thing. And for power rails you need ...
by TmEE co.(TM)
Wed May 23, 2018 9:31 pm
Forum: Megadrive/Genesis
Topic: Color analysis between different emulators/editors
Replies: 5
Views: 451

Re: Color analysis between different emulators/editors

The video DAC part is figured out pretty much. There's 17 taps on a long resistor structure and each tap is turned on with a control signal to enable certain level on the color channel output. 15 MD mode levels plus two SMS mode exclusive levels.
by TmEE co.(TM)
Thu Apr 26, 2018 6:17 pm
Forum: Megadrive/Genesis
Topic: Struct maros/syntax and naming conventions
Replies: 6
Views: 550

Re: Struct maros/syntax and naming conventions

I do stuff like that :

OffsetName EQU 124

MOVE.W OffsetName(A0), D0

EDIT: Exactly what you try to avoid... lol. I don't know of any better solution.
by TmEE co.(TM)
Wed Apr 04, 2018 6:30 pm
Forum: Megadrive/Genesis
Topic: Game loops and Vertical Blank interupts
Replies: 29
Views: 1371

Re: Game loops and Vertical Blank interupts

I poll for VBL bit in the VDP in main loop and I also set a flag in the frame interrupt. If main loop sees that the flag is set after all game logic it can assume slowdown has happened and act upon it, when flag isn't set the logic ended before frame did.
by TmEE co.(TM)
Sat Mar 17, 2018 7:41 am
Forum: SGDK
Topic: Rescomp colour conversion
Replies: 3
Views: 327

Re: Rescomp colour conversion

I just do 255/34 in my tools and it works for linear and the nonlinear ramp too.
by TmEE co.(TM)
Fri Mar 16, 2018 6:06 am
Forum: Megadrive/Genesis
Topic: Where do I start? I'm seeking technical documents.
Replies: 40
Views: 2726

Re: Where do I start? I'm seeking technical documents.

Just for code I have couple old things that can be looked at : My first game on MD, very poor code : http://www.tmeeco.eu/SMD/GBMD11S.RAR Pong game that doesn't use RAM at all : http://www.tmeeco.eu/BitShit/PONG!RAM.ASM And for some less terrible stuff here's a disassembly of the TMSS ROM I made a w...
by TmEE co.(TM)
Tue Mar 06, 2018 5:59 pm
Forum: Megadrive/Genesis
Topic: Where do I start? I'm seeking technical documents.
Replies: 40
Views: 2726

Re: Where do I start? I'm seeking technical documents.

Interrupts are auto-acknowledged on MD, there's no need to read the status port to get the next interrupt. Also on Z80 side, IRQ lasts entire line and if your handler finishes early it'll be called again due to it.
by TmEE co.(TM)
Tue Feb 27, 2018 3:54 pm
Forum: Megadrive/Genesis
Topic: Where do I start? I'm seeking technical documents.
Replies: 40
Views: 2726

Re: Where do I start? I'm seeking technical documents.

Only SMS/GG actually use the first index in a visible way, no other console does. So you're limited to using backdrop to make use of those first 4 indexes of each palette.
by TmEE co.(TM)
Tue Jan 16, 2018 10:18 pm
Forum: Super 32X
Topic: Cartridge bigger than 32Mbits ?
Replies: 27
Views: 14783

Re: Cartridge bigger than 32Mbits ?

Your bank writes goes to high byte (D8....D15), you'll have to do MOVE.W #$bb00, ($A130xx) where bb is your bank number to get the number go to low byte (D0...D7) which the mapper responds to. Little-endian vs Big-Endian business.
by TmEE co.(TM)
Mon Dec 11, 2017 11:00 pm
Forum: Demos
Topic: Xeno Crisis
Replies: 3
Views: 649

Re: Xeno Crisis

I do wish the arenas get bigger and scroll around like Alien Syndrome. Single screen stages make things pretty underwhelming...
Music side of things has me interested though. Good luck ~