Genesis / Megadrive core ported to MiST

[slingshot]

I just "reported" that because it's a bit funny how it looked impossible some years ago, now the SDRAM controller doesn't even sweat to perform cycle-exact memory access

[Total Eclipse]

The only thing I've found that completely fails so far is the Stuck Somewhere In Time demo. That reports that it's being run in an emulator, presumably due to checking CPU timings?

Just over a year on and I've tried the last release and noticed that it's been fixed. I'm not sure which update in the past 12 months resolved it, but well done to all involved.

[Televicious]

Just curious, is anyone trying to bring sega cd addition to MiST? Is it possible? I'm betting 32x is way over spec for size.

[slingshot]

Just curious, is anyone trying to bring sega cd addition to MiST? Is it possible? I'm betting 32x is way over spec for size.

Probably Sega CD alone would fit. But where to put the base Genesis?

[Televicious]

Oh so it does need both 68000's to run and that's too much.

[slingshot]

Oh so it does need both 68000's to run and that's too much.

Not just 2 68000s, but 2 VDPs, 2 sound chips, and memory bandwidth for both parts.

[vebxenon]

Hello:

I'm using last core version, and I've found some problems using for example these games:

- Mega Games 2 (I need to load the cart several times before booting)
- Mega Games 3 (I need also to load the cart several times, and It sounds baldy)
- MegaMan The Wily Wars (PAL, It doesn't load at all)

Do you have the same problems??

[vebxenon]

Hello:

I'm using last core version, and I've found some problems using for example these games:

- Mega Games 2 (I need to load the cart several times before booting)
- Mega Games 3 (I need also to load the cart several times, and It sounds baldy)
- MegaMan The Wily Wars (PAL, It doesn't load at all)

Do you have the same problems??

Using fpgagen_20190815.rbf core these games works perfect, just tested. Both Mega Games compilations load at first time and no sound/load issues.

MegaMan The Willy Wars works using Fake EEPROM.

[vebxenon]

Well, Slingshot has fixed these problems

https://github.com/mist-devel/mist-bina ... 200204.rbf

FPGAGen: fix fake EEPROM, disable refresh emulation - causes troubles

Thanks very much!!

[DanyPPC]

Well done !

[DrOG]

Nice job!

[vebxenon]

I've found that Joe and Mac rom hangs using last core

I'm using this file (uploaded just for testing purposes) : https://mega.nz/#!IQBhBApb!MpUvzz5R2F3g ... 46-260ZkDo

Can you test it, please?

Regards,

Salva

[DanyPPC]

I confirm.

[vebxenon]

New update on Mega Drive core https://github.com/mist-devel/mist-bina ... es/fpgagen

Let's try it!!

[Chris23235]

Oh great, many thanks, the changelog says

FPGAGen: another attempt for refresh delay emulation

What exactly does this mean?

[slingshot]

Oh great, many thanks, the changelog says

FPGAGen: another attempt for refresh delay emulation

What exactly does this mean?

On the real Genesis, the CPU is halted when the bus controller issues a refresh cycle to the internal RAM, and even to the external ROM (which doesn't need refresh, but still...). This slows down the CPU a bit, and if it's not simulated for an extent, some games doesn't work properly.
Hopefully Joe&Mac will work again, and other games won't break (but who knows).

[Chris23235]

Thanks for the explanation.

[Xtro]

Just found that fpgagen_200523.rbf with latest firmware breaks sound on some games, for example with ESWAT: City under Siege

[slingshot]

Just found that fpgagen_200523.rbf with latest firmware breaks sound on some games, for example with ESWAT: City under Siege

Hehe, this bloody bus controller never will be perfect. The 315-5364 chip should be really decapped and reverse-engineered.

[slingshot]

Just found that fpgagen_200523.rbf with latest firmware breaks sound on some games, for example with ESWAT: City under Siege

Well, this game is buggy, as it writes to the ZRAM, it forgets to disable interrupts and suddenly the Z80 bus request is cancelled. I wonder what will happen if I enable the Z80 bus access for the 68k even if its bus is not acquired. Currently you can enable Turbo CPU, then the ZRAM access will finished before the interrupt messes it up.

[Xtro]

You are right, enabling CPU=Turbo fixes sound on ESWAT

[slingshot]

You are right, enabling CPU=Turbo fixes sound on ESWAT

I've developed a fix for the buggy ZRAM access (bit of oxymoron), what are the other games which are wrong currently?

[Xtro]

Sorry, I only had this problem with ESWAT but as was one of the few games I tried thought other games could be wrong too

[slingshot]

Sorry, I only had this problem with ESWAT but as was one of the few games I tried thought other games could be wrong too

OK. Well, this should fix it:
https://github.com/mist-devel/mist-bina ... 200821.rbf

[vebxenon]

Sorry, I only had this problem with ESWAT but as was one of the few games I tried thought other games could be wrong too

OK. Well, this should fix it:
https://github.com/mist-devel/mist-bina ... 200821.rbf

Great! Thanks very much!