HX-34 memory upgrade

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Por Manuel

Ascended (18075)

imagem de Manuel

17-09-2010, 23:00

I am happy to contribute to the activity of openmsx.

I'm sorry, I'll try to upgrade memory first. after succeeded it,
next I'll try to run makerom.bas.

Thank you very much for your concern! Smile

The best program is "getrom.bin", which can be found easily with Google (let me know if you can't). Also, having an idea about the memory layout is very useful, and for that you can use http://crap.tsk-tsk.net/msxmem2.zip (thanks Hap!)

If you open the machine, could you make some photographs of the motherboard, so we can see which chips are on? Also, for correct keyboard emulation, a photo of the keyboard would be nice.

The output of this program is also kind of useful, if we really want all details: http://crap.tsk-tsk.net/ident_test.zip

Anyway, all of this, if you have the time, of course. Just let me know if you have something and I'll try to create an openMSX hardware config file for it!

Thanks a lot in advance for any help.

Por kansaizine

Supporter (13)

imagem de kansaizine

18-09-2010, 00:21

Thanks to all for many reply.

@NYYRIKKI
OUT &HFF,3 -> Crash (and it was automatically soft-reset)

@RetroTechie
PRINT INP(255) -> 248

Memory-mapper seems to be installed... right? Question

@manuel
Thank you for introducing a nice utility.
I'll try later and report of the result.

@Eugeny_Brychkov, @manuel
I'll take the photograph and uploads it somewhere.

Por RetroTechie

Paragon (1563)

imagem de RetroTechie

18-09-2010, 01:03

OUT &HFF,3 -> Crash (and it was automatically soft-reset)

@RetroTechie
PRINT INP(255) -> 248
Looks like a 128K memory mapper... with 64K present, you'd want to know if that 128K consists of [64K, 2x mirrored] or [64K RAM + 64K empty]. Try the following:

OUT 255,4

If nothing happens, mapper blocks 4-7 are mirrors of block 0-3 and adding another 64K probably needs a solder bridge / jumper change somewhere.

If machine hangs/resets, blocks 4-7 are empty & with a bit of luck putting in the missing IC's will do the trick.

Por kansaizine

Supporter (13)

imagem de kansaizine

18-09-2010, 02:45

oh... nothing happens...
I came to have to look for the jumper... Crying

Por RetroTechie

Paragon (1563)

imagem de RetroTechie

18-09-2010, 03:25

I suggest you do some resistance measurements + tracing of PCB tracks, to find out how the DRAM control signals /RAS, /CAS, /WE and /OE are connected, and find out where those signals come from (including the empty IC places in your 'research'). BA-team Grab eg. this datasheet for pinout.
Knowing what other parts are in the machine (MSX engine, custom IC's etc) are in the machine, would also help. Or detailed pix of course...

Por kansaizine

Supporter (13)

imagem de kansaizine

18-09-2010, 09:36

Because I am not a specialist of hardware, the work is very difficult for me... Tongue
I think that I take the photograph of the main board first.

Por Manuel

Ascended (18075)

imagem de Manuel

18-09-2010, 11:05

Interesting, I've never heard of a machine behaving like it has a 128kB mapper, but only 64kB installed. Are there more machines like this, RetroTechie?

Por Repair-Bas

Paragon (1115)

imagem de Repair-Bas

18-09-2010, 11:24

there are more Japanese MSX computers with 64 kb and space for 128 kb

Sanyo Wavy 70FD*
Panasonic A1F(M)

Por Manuel

Ascended (18075)

imagem de Manuel

18-09-2010, 11:55

And do those also mirror the first 64kB to the 2nd 64kB?

Por kansaizine

Supporter (13)

imagem de kansaizine

18-09-2010, 12:15

I also have a 128kb-ed FS-A1F. It has no jumper settings required for 128KB.
I can't check now whether it is mirrored because IC socket is not used...

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