HX-34 memory upgrade

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Por Manuel

Ascended (18088)

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24-12-2020, 16:35

Por msxholder

Champion (382)

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24-12-2020, 22:29

There are only 4 values at register 7FFFh 9C,9D,9E and 9F hex.
Time to dismantle that thing.

Por popolon_

Master (162)

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25-12-2020, 16:21

Por mars2000you

Enlighted (5963)

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25-12-2020, 17:49

The 80kB ROM can be found inside this dump. The mapper seems to be a variant of ASCII16 with SRAM.

To test the firmware:

* CALL JWP for the Japanese Word Processor
* CALL EWP for the English Word Processor

Por Manuel

Ascended (18088)

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25-12-2020, 22:53

80kB? I see 13 different 8kB blocks in the dump. So I think it's at least 104kB; so probably 128kB physically. But the pattern doesn't make much sense to me yet. See the openMSX ticket where I documented this analysis: https://github.com/openMSX/openMSX/issues/1157

Por popolon_

Master (162)

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25-12-2020, 23:22

Shuold i try to dump rom by extracting the one in socket and reading it on mini pro programmer?

Por mars2000you

Enlighted (5963)

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26-12-2020, 00:07

According the infos I got in the past from a Japanese user, it must be 80kB. I think it's the block between 3C000H and 4FFFFH.

Details:
- first 16kB = RS-232C BASIC + Printer BASIC + the extra instructions to launch the WPs
- next 32kB = Japanese Word Processor
- last 32kB = English Word Processor

Por Manuel

Ascended (18088)

imagem de Manuel

26-12-2020, 00:41

popolon_: a direct dump from the ROM chip would be fantastic!

mars2000you: if you take that part, we are ignoring 3 unique blocks, which I numbered as 1, 2 and 3.

Por mars2000you

Enlighted (5963)

imagem de mars2000you

26-12-2020, 01:02

There is almost no difference between block 0 and the blocks 1 to 3.

The only difference is at address 3FFF - value 9C, 9D, 9E or 9F what corresponds to what msxholder has noticed for register at address 7FFF.

Por Manuel

Ascended (18088)

imagem de Manuel

26-12-2020, 01:04

Aha that could explain things, thanks! I wasn't that far with the analysis.

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