how can I rewrite my msx2 nms8280 bios?

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By tcruise

Master (131)

tcruise's picture

15-02-2011, 02:22

Yes thank you, I might be able to go through this list and check the components and solder connections in my DOA unit I got from Bas that the delivery people (it is a long way) must have given a hard time.

By ro

Guardian (4123)

ro's picture

15-02-2011, 12:52

google translate anybody Wink

By barman26

Supporter (6)

barman26's picture

09-09-2017, 04:24

hello again.
6 years later I'm upgrading my NMS8250 to MSX2+. Wink
And I have a little question.
The diode 1N41481 will connect pin 26 of V9958 to pin 24 of Z80.
But in what orientation?
These pins are WAIT state of every IC. And I think that this signal out from Z80 to VDP. Consequently the positive of side of diode will be connected to Z80 and negative to VDP. This is correct?

By Philip

Champion (371)

Philip's picture

09-09-2017, 08:15

Recently I upgraded my 8250 to msx2+ (except I skipped the F4 register stuff and changed the bios so it will always show the logo on boot).
There was some discussion recently on this forum if this diode is really necessary, so I decided to try it without....
And it turns out everything works fine, even f1 spirit 3d special.

By Grauw

Ascended (8457)

Grauw's picture

09-09-2017, 12:51

No MSX2+ or turboR has V9958 WAIT connected, so naturally all games work fine, because it is the normal configuration.

About F4, I think I recall that the MSX2+ BIOS does a destructive RAM search on hard reset...? So if not connected, maybe cracks or tools which reboot the system after loading will not work...?

By sd_snatcher

Prophet (3069)

sd_snatcher's picture

09-09-2017, 13:46

In fact, both the CIEL ExpertTurbo and Expert3 motherboards have the V9958 WAIT signal connected and fully functional. Smile

By Grauw

Ascended (8457)

Grauw's picture

09-09-2017, 15:17

Yes, but those were homebrew boards, right, modded machines (and I think you said elsewhere that it was not functioning fully correctly either). I’m talking about official Japanese MSX2+ / turboR machines.

Point is, there’s nothing surprising about everything working fine, because it’s not normally hooked up either. You can connect it, but if there is no turbo it will do no good. And if you’re not sure how to connect it, then might as well save you the trouble, just one less thing that can go wrong. No MSX2+ software is written nor will ever be written to use the V9958 WAIT feature, because that software will not be compatible.

By Jipe

Paragon (1366)

Jipe's picture

09-09-2017, 15:16

Graphsaurus ans Synthe Saurus required the F4 port for start

By Philip

Champion (371)

Philip's picture

09-09-2017, 16:44

Well, yes, the msx2+ bios does a destructive ram search on hard reset. But I could think of only one thing which requires a reboot to start, and that was that cracked msxdos2 which one could run with 2 memory mappers.
But graphsaurus an synthesaurus seems like a perfect valid reason to add the F4 register. I wonder if there is more software who needs it ?

By Philip

Champion (371)

Philip's picture

09-09-2017, 19:56

I tried a .dsk version of graph saurus with sofarunit and it seems to work fine without F4 register.
Perhaps it's the harddisk version I read something about that needs the F4 register ?

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