Upgrade SCSI / Mods

[Synthiepop80]

Hi @All, Need somebody's help for getting clear about the inside of my EMAX 1:

Understanding for SCSI upgrade this Chips are needed:
- A5380 SCSI chip at IP6
- The 28 pin Plus OS boot ROM labeled IP355 at IC13
- The HD or Plus TIM PAL at IC49 (IP356 or IP379)

And before making my mind about SCSI upgrade I have to check about the board - in my case that's a CPU PCB PC320, Version 1 Rev. A. Now most of the technical skilled users will shout "no upgrade possible", but due to their truly correct opinion there were some mods already done on my board:

- A5380 SCSI chip at IC6: There's None, socket is free
- The 28 pin Plus OS boot ROM labeled IP355 at IC13: no, but IP349 Rev A at IC13 installed
- The HD or Plus TIM PAL at IC49 (IP356 or IP379): no, but IP344 Rev B at IC49 installed
- Additional IP345 Rev C at IC26 installed
- Mod IC54 to IC2 and RNI
- Modification Connection IC48 to C46 and R19
- IC48: Modified 39-52 ns to 45-55 ns - what for?

Does anybody know what happened to my board or can anyone detect the Intention of that modifications? Thanks and best from Germany,
Michael

[ddvdave]

Hi Michael,

Those mods you see are standard factory mods that have nothing to do with SCSI (they are fixes which needed to be applied after the boards were fabricated). Unfortunately you have a Version 1 Rev A. CPU board, which is not upgradeable to SCSI.

See here for details.

-Dave

[Synthiepop80]

Hi Dave,

First of all thanks for your Message, was barely The only one I got for the mods, and I already was afraid there'll be no way for SCSI upgrade at a model 1000 of 1986 which ought to be one of the first EMAX (I) and serial <300 which ever left the EMU factory. All IC / EPROMs are doing good, there's no humidity at all and the condition is good, too - not bad if you think of barely 30- year- old ;-)

It's amazing EMU had to do modifications AFTER the fabrication, guess it was a great time in the Mid-80ies doing researches on technology and detecting solutions for!

Now with having clarification on the EMAX I'm going to keep it for collection and seek for another one, model HD or SE or what else. In the meantime I built my first EMUser for I had time enough because there was nothing going on in SCSI- issues.

Best from Nuremberg,
Michael