Sunday, March 26, 2017

Zeal E/PASO Communication Tool - part 3

This post brings a sad news: the Zeal E/PASO isn't a MSX machine. I still didn't have the dumps of all ROMs. But, as RetroTechie pointed out in MRC's forum, there are some important connections missing between the Hitachi HD64180 (the main processor), the memories and the Yamaha S3527 (the MSX-SYSTEM). Ricardo Oazem, from Tecnobytes, confirmed this diagnostic.

It's the first time in this blog that a appliance with a MSX-SYSTEM isn't compatible with the MSX architecture. Probably space constraints made Zeal to use the S3527. They needed a keyboard controller and a sound generator, the S3527 have both functions in a package very smaller than a i8255 and a YM2149. The slot handling is not used, the main memory and the embedded software seems to be connected directly to the HD64180.

Even in a machine without the slot handling support, it's possible to run a modified MSX-BIOS, doing a direct mapping the ROM and RAM to the correct addresses. This modified MSX-BIOS can even be used to abstract different port addresses or some hardware incompatibilities. There are "MSX adapters" for other computers with a similar hardware which follows this path to play some MSX games (and probably this works to play almost all 8-32KB games that uses the MSX-BIOS to access the hardware). Maybe this can be done with the Zeal E/PASO.

We now have the contents of these ROM and EPROM.

With the help of many friends at MSX Jau 2016 meeting, now I have two of the ROMs of Zeal E/PASO dumped. The Hitachi HN62321 looks like a Kanji ROM (as we guessed in previous post) and the other labelled as "E/P ver1.00" I did not really know what it is. At first my guess was that the data in there had their bits mixed to help the board circuit routing, but there are some text strings inside the EPROM:

**** P'[*]C NIF'[--->]SVC'[--->]%0'[--->]%1'
******V*A*N*P*C*N*E*C*0*2'[ID: ]%0'[WORD: ]%1'
****[): ]mix'[Name? ]%0'[word: ]%1'
******@**'**[*]c ascii'[ID:]%0'[word:]%1'
******@**'**[*]a eye'[CONNECTED]'[CODE:]'[ID:]%0'[WORD]%1'
****[CODE ->]%0'[WORD ->]%1'
******@**'**[*]a mn'[id :]%0'[word:]%1'

Those text strings looks a lot like PPP's "conversation" strings between a client and a server.  Probably this EPROM is used by the modem controller. If you want to read those ROMs yourself and make your own guesses, you can download both files in this tarball.

With those two EPROMs we still didn't have any code for HD64180/Z80. There a lot of other ROM ICs to read, I hope to have those files soon. Then we'll see if the E/PASO software was derived from MSX-BIOS code and maybe have some clues to adapt a MSX-BIOS to run in this machine. Yes, I still didn't give up the idea of using Zeal E/PASO as a MSX.

And now, the previous posts were updated with the "Not MSX" tag.

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