Viking SCSI controller RS232 adapter

Douglas Taylor dj.taylor4 at
Tue Jun 28 13:29:14 CDT 2022

On 6/28/2022 12:58 PM, Douglas Taylor via cctalk wrote:
> I have a couple of these boards but have never got into the on-board 
> monitor which requires an adapter board that allows a terminal to talk 
> to the controller board and do various things.
> Looking at the manual on bitsavers there is almost enough info to 
> construct my own adapter board.  Has anyone ever built there own 
> adapter to the controller?
> Doug
I wasn't clear about this.  The Viking board I have is a dual width 
q-bus board that connects SCSI  disk or tape devices VAXes or PDP11s 
using MSCP protocol.   In the bitsavers manual on figure 8 is a drawing 
of the 'Serial Port Cable Adapter'.  Table 2 lists the pin-out of the 50 
pin IDC connector and which lines are used for what signal.  In that 
list are these RS232 connections:

IDC pin 20 -> CON TX (RS232)

IDC pin 22 -> CON Rx (RS232)

IDC pin 28 -> FP TX (RS232)

IDC pin 30 -> FP TX (RS232)

I was able to trace these IDC connections back to an ICL232 chip on the 
Viking board which is an RS232 driver chip.

My question is which of these RS232 lines are brought out to the 'Serial 
Port Cable Adapter'?  Which ground do I use?  What do CON and FP stand for?

I am trying to de-bug one of the boards and would like to get into the 
on-board monitor and see what it tells me about the board configuration.


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