HB-F1XD Japanese MSX2 - Replace V9938 with V9958?

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By Colemu

Hero (535)

Colemu's picture

10-09-2012, 01:50

Off to bed, my head hurts Question
Thanks for everyones help so far, nearly gave up a few times, but Nyyrikki gave me a little hope Smile

I'm sure it must be possible to upgrade this machine, somehow!
Cheers Chaps...

By Colemu

Hero (535)

Colemu's picture

10-09-2012, 10:46

Has anyone got a dump from a real HB-F1XDJ (1M-Bit)?

I have ordered a 27C010 as it seems impossible to create a working 64k rom.

I want to just burn the full ROM onto it and try that in my HB-F1XD, surely thats gotta work Wink

By NYYRIKKI

Enlighted (5897)

NYYRIKKI's picture

10-09-2012, 11:32

Colemu wrote:

I have ordered a 27C010 as it seems impossible to create a working 64k rom.

I want to just burn the full ROM onto it and try that in my HB-F1XD, surely thats gotta work Wink

I can fix you the 64K ROM when I have some more free time, but if you plan to go to 128K ROM, then how you are going to do the address decoding and connect slot select signals?

What I think is going on at the moment is that CE signal is connected to SLT0 and SLT30 signals trough OR-gate and A15 is connected to either SLT0 or SLT30. If you wish to add similar ROM as in HB-F1XDJ then you need to figure out how to connect rest of the SLT3X signals and also do new decoding for CE.

If you ask me, then maybe it is more easy to put more ROMs on top of each other and just connect the CE lines of each chip to correct STL3x signals.

BTW as curiosity HB-F1XDJ has also RAM in slot 3-0 instead of 3-3 (Not important during upgrade as the ROM's can find it anyway)

By Colemu

Hero (535)

Colemu's picture

10-09-2012, 11:56

I'll hold off on the 1M-Bit rom then Nyyrikki if you think you can get a working 64k rom. Very much appreciated mate. You're probably right that this is the best route as this will fit right into the board.

In the meantime, I'll fit the V9958.

Thanks! Smile2

I must say, I've been on many forums and this is, by far, is the most helpful one!!

By NYYRIKKI

Enlighted (5897)

NYYRIKKI's picture

10-09-2012, 12:31

When you fit the V9958 can you also check if the A15 (pin 1) of ROM goes to S1985 pin 47 or 53? (This way we can know what is the correct order to burn the ROM-files to ROM-chip)

By Colemu

Hero (535)

Colemu's picture

10-09-2012, 12:42

No problem mate, will do

By NYYRIKKI

Enlighted (5897)

NYYRIKKI's picture

10-09-2012, 14:03

I just tried to boot the MSX2+ configuration on OpenMSX with 64K ROM and had no problems. I also noticed that disk rom of both machines seems to be same.

(How ever I needed to create ROMS folder inside modded configuration folder and remove sha1 checksums from hardware config so that OpenMSX finally wanted to boot my configuration instead of default one)

The mod seems to work ok ATM, but I still want to do more testing and maybe change the mod a bit before I mail it to you.

By Colemu

Hero (535)

Colemu's picture

10-09-2012, 16:45

You're a genius!! Cool

What seamed an impossible job is looking a lot simpler now! Smile

I've odered a couple of sockets - one for the VDP and one for the ROM.

By OeiOeiVogeltje

Paragon (1402)

OeiOeiVogeltje's picture

10-09-2012, 17:47

im still not sure you can simply replace one VDP wth another one since they seem to have different pinouts
like here

By Colemu

Hero (535)

Colemu's picture

10-09-2012, 17:49

Apparently you can. Jipe says that as long as you ground both vsync and hsync
pins 4 to 20 to 27

and connect dac/vdd
pins 21-58

it should work...

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