Trying to dump Yamaha SKW-01

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By sdsnatcher73

Paragon (1725)

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11-04-2021, 07:03

I recently obtained a Yamaha YIS-503 with the SKW-01 Japanese Word Processor installed in the side slot (I got it because of that, obviously Wink) The goal is of course emulation in openMSX!

I dumped the 32kB program ROM using SAVEROM.COM. I tried to dump the Kanji ROM with KANJIROM.BAS but it was not recognized. I guess Kanji ROM access was not standardized in MSX1 times so I wonder if anyone could help figuring out how it is accessed in the SKW-01. It also sports a centronics printer output (of which not much is known as far as I could find).

This the dump of the program ROM.

Some images of the module:

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By Alexey

Guardian (3071)

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11-04-2021, 13:57

Wow! Never seen such a use of the side slot. Is that a printer port there? Can you make pictures of the board from both sides please?

By mars2000you

Enlighted (5833)

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11-04-2021, 18:40

The JWP ROM is actually a 32kB ROM - the part with the AB signature is not at the beginning, as it is often the case with Yamaha roms (but you can build a 'normal' ROM with an hexa editor).

You need to use CALL JWP to launch the JWP.

As mentioned in the Wiki, the Kanji-ROM (JIS1) is non-standard with 3564 characters. I guess you need to use an EPROM reader to dump it.

By sdsnatcher73

Paragon (1725)

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11-04-2021, 21:51

I have the word processor ROM, call JWP works with that in openMSX but it displays incorrectly, I guess because it cannot access the Kanji font. To be able to emulate it it needs to be figured out how the kanji font data is retrieved (by the program ROM). Probably through disassembly of the program ROM this can be determined.

If that is known I thought it would be possible to dump with an altered or special version of kanjirom.bas.

By mars2000you

Enlighted (5833)

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11-04-2021, 21:55

sdsnatcher73 wrote:

I have the word processor ROM, call JWP works with that in openMSX but it displays incorrectly, I guess because it cannot access the Kanji font. To be able to emulate it it needs to be figured out how the kanji font data is retrieved (by the program ROM). Probably through disassembly of the program ROM this can be determined.

If that is known I thought it would be possible to dump with an altered or special version of kanjirom.bas.

The same in blueMSX on a machine with standard Kanji-ROM. This JWP can only work with its non-standard Kanji-ROM.

By sdsnatcher73

Paragon (1725)

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12-04-2021, 05:39

Yes that is understood.

By sdsnatcher73

Paragon (1725)

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13-04-2021, 16:49


By Alexey

Guardian (3071)

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13-04-2021, 18:35

Thanks! What is that YM5520 chip? A printer port controller?

By mars2000you

Enlighted (5833)

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13-04-2021, 18:52

https://twitter.com/sc59_jp/status/1352597083077840899

YM5520:パラレル接続のためのチップ?
YM2301:これがおそらくワープロソフトのプログラムROMが含まれるチップ
MB83256:おそらく漢字フォントROM
TC5517:SRAM

YM2194 が漢字 ROM らしい。
じゃあ MB83256 がワープロソフトのプログラムROM?
そうなると YM2301 は何だろう。
YM2301 は他のこのヤマハ専用のカセットにも搭載されているらしいので、MSX のスロット処理関係のチップかな。

Google translation:
YM5520: Chip for parallel connection?
YM2301: This is probably the chip that contains the program ROM for word processing software
MB83256: Probably Kanji font ROM
TC5517: SRAM

YM2194 seems to be a Kanji ROM.
Then MB83256 is a program ROM for word processing software?
Then what is the YM2301?
It seems that the YM2301 is also installed in other Yamaha-specific cartridges, so I think it's a chip related to slot processing on MSX.

By sdsnatcher73

Paragon (1725)

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13-04-2021, 19:37

YM5220 seems to be a bridge between MSX, Kanji and centronics interface. Also a not common pin scheme (I mean with the 2 rows of pins on each side). Yamaha seems to have pulled out all their engineering skills on this module.

By msxholder

Champion (378)

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13-04-2021, 20:45

YM2301 is a Rom it is data paralel connected to MB83256 .

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