Search found 52 matches

by l_oliveira
Thu Sep 20, 2018 2:51 am
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Re: Regarding the YM3438 on the Mega Drive...

I actually re-installed the YM3438 mod I had made many years ago in one of my MD consoles. I now remember why I undo it. The noise floor was very high and it annoyed me a lot. Anyway, not a single one of my games did fail with it. But I only own Japanese cartridges. One game I know that have problem...
by l_oliveira
Wed Sep 19, 2018 9:11 pm
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Re: Regarding the YM3438 on the Mega Drive...

I forgot to mention this: Consider that people using YM3438 on Mega Drive are actually cheating by piggybacking the YM3438 with the original YM2612 and tying the /RD pin to +5V so the original YM2612 is the one spammed with reads by the system. If it is not done that way, the YM3438 actually fails t...
by l_oliveira
Sun Sep 16, 2018 6:02 pm
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Re: Regarding the YM3438 on the Mega Drive...

We know that the integrated version is not exactly like the YM2612 but it's also not exactly a YM3438 either. Not sure what Yamaha actually did here. Very likely they had it changed from the original YM3438 design so it doesn't break when the games spam reads on the status register. I actually stic...
by l_oliveira
Sun Sep 16, 2018 2:57 pm
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Re: Regarding the YM3438 on the Mega Drive...

I don't think it's even possible to reach a high enough read rate that would cause the YM3438 to glitch on a PC printer port.
by l_oliveira
Sun Sep 16, 2018 5:07 am
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Re: Regarding the YM3438 on the Mega Drive...

For sake of being illustrative, this is the ASM macro I was using for the YM2612 access: OPN2: MACRO super: Driver Driver_PrintInfoImpl ; e = register ; d = value SafeWriteRegister: ld a,e cp 21h ret z ; block TEST register cp 27h jr z,TimerControl ; mask timer control cp 2AH jr z,pcm2612 ; do not w...
by l_oliveira
Sat Sep 15, 2018 9:31 pm
Forum: Sound
Topic: Regarding the YM3438 on the Mega Drive...
Replies: 11
Views: 2136

Regarding the YM3438 on the Mega Drive...

Researching on a hardware design to play Mega Drive VGM data on my beloved MSX platform I have been slowly progressing from just the YM2612 to YM2612 + PCM then YM2612 + PCM + PSG. Even after achieving solid results with the YM2612 chip, I never managed to get the YM3438 to work properly on this set...
by l_oliveira
Mon Dec 12, 2016 1:14 pm
Forum: Mega/SegaCD
Topic: CDC DMA failing on Kega Fusion?
Replies: 8
Views: 2992

Re: CDC DMA failing on Kega Fusion?

That behavior is mentioned in one of the service manuals that got released a couple months ago... They refer to the affected units as "FUNAI units". FUNAI is the company SEGA contracted to build some of their production of MEGA/SEGA CD2 units. FUNAI units are more common in the US, equipped with eit...
by l_oliveira
Thu Dec 08, 2016 1:37 am
Forum: Mega/SegaCD
Topic: CDC DMA failing on Kega Fusion?
Replies: 8
Views: 2992

Re: CDC DMA failing on Kega Fusion?

Certain motherboards from the SEGA/MEGA-CD2 have a different CDC, based on a NEC MCU. Even SEGA/MEGA-CD1 units with a JVC mechanism do have a different CDC and that cause problems with at least one game. KEGA Fusion emulates a CD-ROM drive with the SONY CDC. So some CD BIOSes don't work in it (They'...
by l_oliveira
Tue Sep 01, 2015 2:03 pm
Forum: Hardware
Topic: Understanding a 139 decoder to wire up 2 roms.
Replies: 4
Views: 3722

Re:

/CE is not enough for a 8Mb Cart. Better wording for this ... /CE gives you 4MB of memory window. If you ignore /CE you will have bus conflict problems on systems with MEGA/SEGA-CD unit attached. That's why very big games like Super Street Fighter have mapper chip in them. Pier Solar, too, for exam...
by l_oliveira
Fri Aug 28, 2015 12:50 am
Forum: Announcement
Topic: Don't forget what SpritesMind is
Replies: 17
Views: 9251

Re: Don't forget what SpritesMind is

This forum is a enormous think tank for retro systems programming and research, even the site being focused on SEGA 16bit hardware and peripherals, other systems still benefit enormously from it directly or indirectly. I don't think I need to say anything else. Thank you for keeping this precious re...
by l_oliveira
Fri Mar 20, 2015 7:17 pm
Forum: Hardware
Topic: Model 1 MD PCB hacks topic
Replies: 17
Views: 7557

I think I know the deal about the VA6.8: The VA7 ASIC (same as used in the MD2-VA0 for the most part) - the 315-5487 has some issues with PAL mode, and looking at the date stamps on the ICs between a VA7 and a VA6.8, the first has earlier dates than the latter. so maybe it was an EU-only version, u...
by l_oliveira
Fri Mar 20, 2015 5:07 pm
Forum: Hardware
Topic: Model 1 MD PCB hacks topic
Replies: 17
Views: 7557

Somewhat. There was something weird back then in the old times where we got asian games with megakeys, and I think asian MD systems too, but I don't remeber details :| Japanese SEGA hardware is quite common here because he had a lot of people from here (Brazil) working in Japan through the eighties...
by l_oliveira
Fri Mar 20, 2015 5:01 pm
Forum: Hardware
Topic: Model 1 MD PCB hacks topic
Replies: 17
Views: 7557

Jorge Nuno wrote:It's quite rare yes, I had one and yep it was PAL. No idea if it ever came in NTSC
I've never seen it. And I've seen units from all over the world. Of course PAL stuff is rare here. I bet Asian stuff is quite scarce in Portugal. Is that true ?
by l_oliveira
Fri Mar 20, 2015 4:48 pm
Forum: Hardware
Topic: Model 1 MD PCB hacks topic
Replies: 17
Views: 7557

So that VA6.8 was released when they were almost ready to switch into the chipset with VDP+Bus Arbiter+I/O chips on the 208 pin SMD thing ?

I did not know about that type. PAL only perhaps ?
by l_oliveira
Fri Mar 20, 2015 4:35 pm
Forum: Hardware
Topic: Model 1 MD PCB hacks topic
Replies: 17
Views: 7557

Maybe they forgot about them? I mean the VA6.8 *still* has them and the markings of 5402:VA5 | 5433: VA6, except it says V6.8 on IC BD M5.. text My Japanese MD1 says "IC BD M5" on the board, no VAxx. The VAxx is near the I/O + bus arbiter chip. Here's a picture of someone else's VA5: http://i721.ph...