microvax/vs 2000 expansion base circuitry ?

Carlos E Murillo-Sanchez ce.murillosanchez at gmail.com
Thu Sep 23 18:26:15 CDT 2021

Ethan Dicks via cctalk wrote:
> On Thu, Sep 23, 2021 at 6:41 PM Jonathan Stone via cctalk
> <cctalk at classiccmp.org> wrote:
>> I've read that there is circuitry in the expansion base (BA40A?) has circuitry .  Does anyone know what the circuitry does?  Is it required for SCSI operation?  (I hope not, or I'll have to kludge one up to make use of pk2k SCSI boot-roms!)
> IIRC the DHT32 has a small board in the skirt and the external RD
> interface may have a board as well.  SCSI (for a TK50Z-FA, originally)
> is just a cable.  The 50-pin connector on the mainboard is correctly
> wired for SCSI. It may well have TERMPWR active and not
> current-limited though, if it matters to your target.
> -ethan
Indeed, Ethan.  TERMPWR is active.  I actually have two 1GB disks inside 
mine (I do not
have an expansion box), and I kludged  a centronix  SCSI connector in 
the back to connect
external stuff.

By the way, if anybody needs the four patched rom images, I can share 
them off-list.


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