Search found 934 matches

by Sik
Fri Jan 03, 2020 9:26 pm
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 3361

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: 3361

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...
by Sik
Wed Jan 01, 2020 5:56 am
Forum: Hardware
Topic: Most up to date Mega Drive cart pinout?
Replies: 6
Views: 3361

Re: Most up to date Mega Drive cart pinout?

This is something I should have documented in Plutiedev long ago… eh. I'll try to get around that soon. Leaving this here meanwhile (B side is the front of the cartridge): https://i.imgur.com/gNLSkhs.png I was going to write a list of everything but I have doubts about some lines (I'm not the expert...
by Sik
Thu Nov 28, 2019 10:56 am
Forum: SGDK
Topic: m68k at risk of being dropped from gcc 11
Replies: 7
Views: 5414

Re: m68k at risk of being dropped from gcc 11

Shame I can't get it to show what was the final bounty amount (I'm probably doing something stupid?). I remember it had reached $6000 some days before it was claimed.
by Sik
Wed Nov 27, 2019 1:04 am
Forum: Tools
Topic: Aseprite Mega Drive Digitizer
Replies: 19
Views: 13059

Re: Aseprite Mega Drive Digitizer

I think I've seen emulators go that far to emulate composite, but it still fails to account for differing TV comb filter quality and such. Also there's the problem where these days you can't reasonably predict what the output method will be, to be blunt. Some people may just grab the original cables...
by Sik
Tue Nov 19, 2019 4:22 pm
Forum: Megadrive/Genesis
Topic: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?
Replies: 28
Views: 12618

Re: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?

When you assert bus request, what you're doing is asking the Z80 to let its bus alone — which may take a bit of time, since it needs to finish any ongoing access first. You're supposed to read back from $A11100 to know when the Z80 has done that. The problem is that while the Z80 is reset it will ne...
by Sik
Tue Nov 19, 2019 3:16 am
Forum: Megadrive/Genesis
Topic: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?
Replies: 28
Views: 12618

Re: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?

I've had it break (inconsistently… it starts making weird noises) when doing less than 192 cycles, so yeah. To be fair it's possible that the actual amount needed is less, but doing more doesn't hurt. From what I recall, I got the 192 cycles amount by looking at docs. Considering how some problems s...
by Sik
Mon Nov 18, 2019 7:50 pm
Forum: Megadrive/Genesis
Topic: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?
Replies: 28
Views: 12618

Re: Noob questions: DEFINITIVE info about Z80 BUSREQ, RESET?

It's… messier than that: https://plutiedev.com/using-the-z80#loading-z80 Or also from the Sega docs (though it's essentially describing the same thing): Z80 Start-Up Z-80 Operation Sequence: BUS REQ ON BUS RESET OFF 68k copies program into Z-80 S-RAM BUS RESET ON BUS REQ OFF BUS RESET OFF The bigges...
by Sik
Tue Nov 12, 2019 6:42 pm
Forum: Megadrive/Genesis
Topic: DMA and FIFO
Replies: 11
Views: 5960

Re: DMA and FIFO

The VDP control and data ports? Yes.

Emulators may handle them in a separate file since they're likely implementing them in the code handling memory accesses (which has no equivalent in real hardware, except maybe the bus itself), but emulators aren't necessarily modelling how real hardware works.
by Sik
Mon Nov 11, 2019 6:15 pm
Forum: SGDK
Topic: NOOB question - How do I get the frame count?
Replies: 8
Views: 3547

Re: NOOB question - How do I get the frame count?

Yeah, sounds like you ended up looking something completely unrelated (・ω・;) Your own counters that go up every frame (like there) is the way to go, regardless of platform. Remember to not increment it while the game is paused. In a complex game you probably will even have multiple of those for diff...
by Sik
Fri Oct 25, 2019 8:19 pm
Forum: Demos
Topic: Street Fighter Alpha Mockup
Replies: 19
Views: 10142

Re: Street Fighter Alpha Mockup

You realize that 2×7KB×2 = 28KB which is almost half of VRAM, right? And also some of the bandwidth needs to be put aside for stuff like the sprite and scroll tables. Incidentally the method I described goes by the assumption that each character isn't uploading a new image every frame, and when they...
by Sik
Fri Oct 25, 2019 3:11 pm
Forum: Demos
Topic: Street Fighter Alpha Mockup
Replies: 19
Views: 10142

Re: Street Fighter Alpha Mockup

The CPS-2's resolution is tricky. Usually it's 384x224. It's got the same pixel height as an NTSC MD, but wider. Though was it treated as wide-screen or was it 4:3 in the arcades? It was 4:3 (with non-square pixels). 320x224 with 20% narrower sprites would be ok, but yeah 320x200 would be better. B...
by Sik
Fri Oct 25, 2019 10:25 am
Forum: Demos
Topic: Street Fighter Alpha Mockup
Replies: 19
Views: 10142

Re: Street Fighter Alpha Mockup

You can work around the sprite update issue by making sure only one updates at a time (e.g. if both need to update at once, then delay one of the players by one frame). Keep hitbox processing and momentum and such all working as normal, this only affects the sprite being shown on screen. I've tried ...
by Sik
Sun Oct 20, 2019 4:37 pm
Forum: Regen
Topic: What is commercial use?
Replies: 4
Views: 11996

Re: What is commercial use?

And this is why one should avoid writing "commercial use" as a blanket statement :​v Also I always find that one fun since distributing those ROMs is illegal in itself, but I guess the idea is to alert any unaware users who download it to see if somebody complains (and to make it clear you don't app...
by Sik
Thu Oct 17, 2019 7:52 am
Forum: Controls
Topic: New device letters
Replies: 20
Views: 14198

Re: New device letters

So I was looking at the Saturn standards doc for unrelated reasons and: https://i.imgur.com/4OqIb0D.png https://i.imgur.com/88z3B0s.png Turns out they do call it the 8-button pad (or at least they did it here). Go figure. I'd say to still stick to "j" for consistency though. Also something that hits...