Search found 917 matches

by Sik
Wed Apr 01, 2020 4:48 am
Forum: SGDK
Topic: Brainstorming a way to hscan colors in SGDK
Replies: 6
Views: 192

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: 157

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: 2681

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: 2681

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: 5156

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: 2768

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: 5156

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: 5156

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...
by Sik
Wed Jan 15, 2020 5:30 pm
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 5156

Re: Cartridge slot questions

*wonders if Tiido noticed that edit* Alright, still trying to understand what /CAS2 does no matter how many times I get it explained x_X So far all I can seem to understand for sure is that /CAS0 asserts before it and that /ASEL is somehow involved (not sure about /ASEL's timing though). Oh, and th...
by Sik
Thu Jan 09, 2020 4:21 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 5156

Re: Cartridge slot questions

OK this kinda stalled. Forgot to mention that when the Master System stuff was probed the video signals remained intact (if useless due to being stuck with a H40 clock), so there goes the whole deal with EDCLK, /HSYNC, /VSYNC and /YS. Was discussing this in Plutiedev and our guesstimation from that ...
by Sik
Mon Jan 06, 2020 5:23 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 5156

Re: Cartridge slot questions

I suppose it would be nice to know what range the 32X outputs on the audio lines (though I heard reports that the 32X's output may be a bit too loud). It is the one piece of official hardware that makes use of it. Also the cartridges with YM2413 seem to use its output directly (?) so maybe looking a...
by Sik
Sun Jan 05, 2020 6:42 pm
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 5156

Re: Cartridge slot questions

That still doesn't tell me what voltage range you should use to keep the audio signal in a "reasonable" range (I'm not a Mega Drive circuit expert :v), only that it's mixed as-is with the rest of the audio (my initial guess would be that the ideal range would be ±1V but honestly I could be wildly wr...
by Sik
Sat Jan 04, 2020 8:49 pm
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 5156

Cartridge slot questions

Here I am trying to document the cartridge slot because it turns out that trying to find anything is a pain in the ass (let alone anything accurate). No wonder this thread exists. The function of the pins in Master System mode is woefully underdocumented. Those that are the same function are easy to...
by Sik
Fri Jan 03, 2020 9:26 pm
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 1819

Re: Most up to date Mega Drive cart pinout?

(Also confusing me is that the Sonic 3 cart uses !TIME as the clock to a D-type register for bankswitching without combining it with an output enable or read strobe.) I don't think it ever bothers to read back the value (only write), makes sense that it won't allow reads from it. They were trying t...
by Sik
Fri Jan 03, 2020 6:08 pm
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 1819

Re: Most up to date Mega Drive cart pinout?

Are the cart port's B28 !LWr and B29 !UWr asserted for the whole address space? As far as I know, yes. /UWR is for the upper byte, /LWR is for the lower byte (i.e. they're the write enables for each half of the word). For byte accesses only one is asserted, for word accesses both are asserted. Does...