mahlemiut WIP

Chad · Post by **Chad** » Tue Dec 09, 2003 5:36 am

wish i could understand emulation code enough to do something similar, i get thrown for a loop ever time i look at the ROM_START() #declaration, nice job Barry!

Post by **mahlemiut** » Wed Apr 07, 2004 10:36 pm

Back to looking at Megaplay. If no one else wants to look at it.... I guess someone ought to.

Memory test now is completed. IC-3, IC-37, and IC-36 come up bad still. Must investigate this further.

Also added the second SN76489 (part of the SMS VDP). Now you get a sound when you insert a credit.

Post by **mahlemiut** » Sun Apr 18, 2004 10:33 am

Sonic the Hedgehog hiscore screen. I've somehow got it to trigger a demo loop... I wish I knew how.

No, I have no idea why the table data is corrupt.

Haze · Post by **Haze** » Sun Apr 18, 2004 12:17 pm

Post by **mahlemiut** » Sun Apr 18, 2004 3:01 pm

Sonic and Tecmo World Cup now coin up and run demos at the right time. Still can't start them however.

EDIT: Actually, you CAN start them - button 4 being the Start button.

zlk · Post by **zlk** » Sun Apr 18, 2004 11:48 pm

Keep up the good work!

QRS · Post by **QRS** » Mon Apr 19, 2004 7:30 am

Nice work Barry! Now go and fix the sound in Vandyke

Post by **mahlemiut** » Mon Apr 19, 2004 8:11 am

In-game DIP switches now work.
Instructions appear.
One more test passes. Only one more to figure out (IC-3 is only marked bad because of the startup kludge).

Still many things to do. Like cleaning up the driver, and splitting Megatech/Megaplay from the C2 driver. Sounds like work.

http://mahlemiut.marpirc.net/segac2-update1904-2.zip

The TJT · Post by **The TJT** » Mon Apr 19, 2004 11:05 am

Nice

Btw, what happened to Malzak...Can not submit at Marp?
Maybe I'll have to go after Alex Lux's Scramble semi-marathon then...

Post by **mahlemiut** » Mon Apr 19, 2004 11:11 am

Malzak is archived as it lacks collision detection. To get it working, I'll have to figure out just what those dozen-odd wires coming out of one of the S2636s (sprite chips) are supposed to do. An S2636 pinout might help, but I've never found one online.

The TJT · Post by **The TJT** » Mon Apr 19, 2004 11:41 am

I searched google, and first link with s2636s search was:
http://www.watchersweb.com/stories/s2636.htm

I guess this won't help, nice family story though

Haze · Post by **Haze** » Mon Apr 19, 2004 8:25 pm

btw barry, if you want to fix the megaplay logo then you need the yflip on the tiles doing something ...

find this code in segasyse.c and add the last 2 lines to it

tile_no = (vram_word & 0x01ff);
flipx = (vram_word & 0x0200) >> 9;
flipy = (vram_word & 0x0400) >> 10;
palette = (vram_word & 0x0800) >> 11;
priority= (vram_word & 0x1000) >> 12;

tilesline2= (line + vscroll) % 8;
if (flipy) tilesline2 = 7-tilesline2;

Haze · Post by **Haze** » Mon Apr 19, 2004 8:32 pm

QRS wrote:Nice work Barry! Now go and fix the sound in Vandyke

custom nmk sound cpu / mcu, chances are it has internal code which can't be dumped (sound 'program' roms appear to contain data only)

might be possible to interpret the data and simulate it (although thats far from ideal) but emulating it may well be impossible.

QRS · Post by **QRS** » Mon Apr 19, 2004 9:32 pm

Haze wrote: custom nmk sound cpu / mcu, chances are it has internal code which can't be dumped (sound 'program' roms appear to contain data only)

might be possible to interpret the data and simulate it (although thats far from ideal) but emulating it may well be impossible.

Yeah, Barry told me a long time ago (not in detail) that it may indeed be impossible to do it

I was just trying to boost him by saying "if he can fix the megaplay games, sure he can fix anything!"

Post by **mahlemiut** » Tue Apr 20, 2004 9:17 pm

Fixed SMS VDP Y-Flip (thanks Haze)

Golden Axe II now starts and is playable.

The Megatech version of Golden Axe II should be startable now too, I have no idea where that fix went, but it's in there now. I'll fix it up to be the same as for Megaplay eventually, but this will do for now.

http://mahlemiut.marpirc.net/segac2-update2104.zip

Current issues:
How the BIOS tells the 68000 to reset has yet to determined. Games can go quite nutty after exiting from test mode, especially after the memory test.
Continuing without any credits in Sonic and Golden Axe II. Tecmo World Cup is fine here as for this game, the BIOS controls the continue functions.
Golden Axe II reads the amount of credits from 0xa02001 - just how that gets there is something to still figure out...

Note: Haze, if you want to switch off the GAME_NOT_WORKING flag, then that's fine with me. It's your call.