Search found 924 matches

by Sik
Thu Jun 25, 2020 6:49 am
Forum: Megadrive/Genesis
Topic: Most compatible way to jump to game image on hardware - making my own cart
Replies: 21
Views: 681

Re: Most compatible way to jump to game image on hardware - making my own cart

Yeah, "trigger" refers to the letter buttons (several manuals and in a handful of cases the games themselves refer to "A trigger" / "B trigger" / "C trigger"). Contrast with Start button and Directional Pad. B maps to the Atari button because the Master System controller has two buttons and their in...
by Sik
Wed Jun 24, 2020 12:42 pm
Forum: Megadrive/Genesis
Topic: Most compatible way to jump to game image on hardware - making my own cart
Replies: 21
Views: 681

Re: Most compatible way to jump to game image on hardware - making my own cart

Edit - I'm putting together a new spreadsheet of Sonic mods changed by the IO fix, and I'm trying Griel's Quest again. It turns out that on the level select menu, for some bonkers reason buttons A and C are 'confirm' and B is 'back', which is outrageous! Uuuuuh, what else do you expect them to be? ...
by Sik
Mon Jun 22, 2020 9:46 am
Forum: Megadrive/Genesis
Topic: Most compatible way to jump to game image on hardware - making my own cart
Replies: 21
Views: 681

Re: Most compatible way to jump to game image on hardware - making my own cart

If BlastEm barfs at a hack you can probably assume the issue is the hack :​P And yeah, games rely on telling apart between cold and warm boot not only because of the init skip stuff (not sure why Sega insisted on that ), but also because most games don't reset the options when you press the Reset bu...
by Sik
Fri Jun 19, 2020 5:30 pm
Forum: Megadrive/Genesis
Topic: Most compatible way to jump to game image on hardware - making my own cart
Replies: 21
Views: 681

Re: Most compatible way to jump to game image on hardware - making my own cart

Yeah, interrupts have to be disabled because that's what 68000 does on reboot (remember not all systems have TMSS so on those the game is the bootstrap). And yeah, the state of the I/O ports on boot is how games tell apart soft reset from hard reset. Also, Z80 should be left reset on boot as well (a...
by Sik
Mon May 04, 2020 4:43 am
Forum: Megadrive/Genesis
Topic: Alternative to Vasm assembler?
Replies: 27
Views: 2616

Re: Alternative to Vasm assembler?

Make sure to enable errors. For some reason asmx has error reporting disabled by default… (why is that even a setting?!)
by Sik
Wed Apr 29, 2020 12:10 am
Forum: SGDK
Topic: Brainstorming a way to hscan colors in SGDK
Replies: 10
Views: 1069

Re: Brainstorming a way to hscan colors in SGDK

Um, you're supposed to do word writes, not byte writes (incidentally, a color is word-sized). You can use longword too (which the VDP sees as two words). Byte writes are likely not doing what you expect. Also this should give you an idea: https://plutiedev.com/tiles-and-palettes#loading-palettes The...
by Sik
Mon Apr 27, 2020 10:30 pm
Forum: SGDK
Topic: SRAM read / write
Replies: 27
Views: 5323

Re: SRAM read / write

You know how you have 32KB worth of SRAM, right? sRamOffSet is the location within SRAM.

sRamOffSet = 0x0000 would be the 1st byte, 0x0001 would be the 2nd byte, 0x0002 would be the 3rd byte, etc. (up to 0x7FFF, the last byte).
by Sik
Wed Apr 01, 2020 4:48 am
Forum: SGDK
Topic: Brainstorming a way to hscan colors in SGDK
Replies: 10
Views: 1069

Re: Brainstorming a way to hscan colors in SGDK

Not related to your question, but how did you manage to miss the Samurai Shodown character select? (especially in 2P) It takes palette swapping even further. Also yeah, timing is a big issue, even if you use asm honestly, because when the 68000 responds to the interrupt the VDP will be likely in a p...
by Sik
Sat Mar 21, 2020 12:29 pm
Forum: SGDK
Topic: Scroll without wrapping
Replies: 2
Views: 648

Re: Scroll without wrapping

You have to keep redrawing the tilemap as the camera scrolls (the tilemap can only hold a chunk of the image, you need to keep drawing in new chunks as it moves around).

EDIT: yes, this goes even for drawing blank tiles :​P
by Sik
Fri Feb 21, 2020 2:54 pm
Forum: Megadrive/Genesis
Topic: Is a space character required at $104?
Replies: 6
Views: 4393

Re: Is a space character required at $104?

In favor of Accolade (even if eventually Sega decided to just give them a license after that anyway). And other countries tend to be more lenient (turns out most jurisdictions are not happy about actively blocking your competition, especially European ones). I'd say that the misleading TMSS message ...
by Sik
Thu Feb 20, 2020 1:37 pm
Forum: Megadrive/Genesis
Topic: Is a space character required at $104?
Replies: 6
Views: 4393

Re: Is a space character required at $104?

Only $100-$103 are checked. That said, not respecting the ROM header is frowned upon so don't do that. Especially since emulators will sometimes rely on the ROM header to detect some stuff (e.g. how much SRAM is installed, or which region to set as default, some may also automatically switch to peri...
by Sik
Sun Feb 09, 2020 9:23 pm
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7638

Re: Cartridge slot questions

OK this stalled again I guess. I'm still not sure how to describe /CAS2 and /ASEL. I know they're related to DRAM refresh, and that /CAS0 asserts before /CAS2 when it happens, but that's it. I'm not sure under what circumstances this refresh cycle is asserted though. Is it regularly? How often? What...
by Sik
Wed Jan 29, 2020 5:11 pm
Forum: SGDK
Topic: Convert PCM to XGM
Replies: 11
Views: 3951

Re: Convert PCM to XGM

Well, you could attempt to add up sine waves (so size still tied to length, but still much smaller than full blown PCM)… but even if it was reduced to a single sound (e.g. speech) I'm not sure how far you can get with just a few sine waves (unless you want to start eating multiple FM channels). I re...
by Sik
Thu Jan 16, 2020 11:04 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7638

Re: Cartridge slot questions

That's the expansion port rather than the cartridge slot. Does that make a difference? I don't think so, many of the signals are shared between the two (and some of the Mega Drive components too), e.g. /CAS0 acts as the output enable for everything that isn't work RAM (for some reason work RAM gets...
by Sik
Thu Jan 16, 2020 12:44 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7638

Re: Cartridge slot questions

Black starts at 25mV above ground and goes up to 800mV with more or less exactly 25mV steps on red and green channels, but blue channel is about 20mV lower in full scale amplitude, which explains the subtle yellow tint compared to MD output that is seen on all 32X I have had access to. 3 2 X Anyway...