Search found 82 matches
- Thu Nov 19, 2015 9:39 am
- Forum: Megadrive/Genesis
- Topic: Artifacts of the direct color DMA
- Replies: 4
- Views: 4361
Re: Artifacts of the direct color DMA
there is no way to "fix CRAM dots, but with clever timing you can avoid them. Sonic 3 is a great example of this; while it doesnt DMA, it writes 3 colours per scanline, with a very precise timing to basically push the dots into overscan. This and some clever code (in case of DMA) and you can squeeze...
- Fri Nov 13, 2015 11:11 am
- Forum: Megadrive/Genesis
- Topic: Clearing the RAM really needed?
- Replies: 5
- Views: 5334
Re: Clearing the RAM really needed?
its not necessary at the least, but you save yourself a lot of unnecessary headache by clearing the RAM anyway.
- Fri Nov 13, 2015 11:07 am
- Forum: Megadrive/Genesis
- Topic: setting a bit on a ram variable
- Replies: 8
- Views: 5674
Re: setting a bit on a ram variable
bclr #FLAG_FRET_GREEN, (fret_flags) ; clear the green fret bit first btst #pad_button_a, d0 ; Check A button bne @NoA ; if button is off, skip setting the bit bset #FLAG_FRET_GREEN, (fret_flags) ; set the green fret bit @NoA: This is the easiest solution; of course there are ways to optimize cycle ...
- Mon Nov 02, 2015 11:30 am
- Forum: Megadrive/Genesis
- Topic: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?
- Replies: 28
- Views: 33963
Re: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?
I'd like something like that Nemesis. And I can test them out, when I hace money for a flash cart, as I have 3 machines mysel (2x model 1 MegaDrive, 1x model 1 Genesis; need to open up to see board revision)
- Sun Oct 11, 2015 10:22 pm
- Forum: Hardware
- Topic: Is move in Motorola 68000 Turing complete?
- Replies: 3
- Views: 8286
Is move in Motorola 68000 Turing complete?
A while back, as we spoke about MoVfuscator, an utility which compiles any C code to only use mov instruction, we thought if move in Motorola 68000 would also be in fact Turing complete. A lot came out of it, but no real way to fully exploit Motorola 68000 with working methods. After that, I took so...
- Fri Oct 09, 2015 9:57 am
- Forum: Megadrive/Genesis
- Topic: 68000 memory map and the significance of address 0x1FFFF
- Replies: 10
- Views: 6297
Re: 68000 memory map and the significance of address 0x1FFFF
I am not sure about SNASM68K, all I know about it is, that I cant even run that assembler in my Win7 64-bit machine. As far as I know the assembler is known for being... bad, at least on Sonic hacking scene. I may be biased, but I'd suggest to use ASM68K (Nemesis version, it fixes lots of issues and...
- Fri Oct 09, 2015 4:21 am
- Forum: Megadrive/Genesis
- Topic: 68000 memory map and the significance of address 0x1FFFF
- Replies: 10
- Views: 6297
Re: 68000 memory map and the significance of address 0x1FFFF
you can not DMA in multiple 128KB areas. In fact 0x20000 is another 128KB bank, therefore the DMA breaks and reads from 0 for bytes past 0x1FFFF, as far as I am aware. This can easily be fixed by making sure no DMA'd data is in 2 128KB areas in ROM.