FS/FT: Two Xerox 6085 computers

Tony Duell ard at p850ug1.demon.co.uk
Wed Jun 15 18:43:00 CDT 2005


I little info as to what you have...

> Xerox 6085
>     Hard drive is labelled as "XPIW 2.0"
>     Cards:
>     P/N 140K05980: LPO (printer port) >--- a half-height card

Local Printer Option. It looks to be Centronics-like.

>         140K05560: IOP (ethernet, floppy, keyboard, serial comm, serial
>                         printer)

I/O Processor. There's an 80186 (or is it an 80188) on this board which 
also loads the microcode in to the MPB. Of course it controls I/O once 
the machine is running. 

>         140K04160: MBP (bus extender port)

Isn't in MPB? That's the Mesa Processor Board (IIRC). The main processor 
with a writeable control store (microcode loaded from disk at boot time), 
a custom sequencer chip and 4 2901-like ALU slices.

>         140K01000: MEB (no ports on this card, extra memory perhaps?)

Memory Expansion Board. What you thought it was.

>         140K00460: DCM (display port)

Display Control and Memory. The basic memory for the machine and the 
video circuitry. Alas there seems to be no video processor in the 6805, 
unlike certain other contemporary machines.

> 
> Xerox 6085
>     Hard drive labelled as "Viewpoint 2.0"
>     Cards:
>     P/N 140K05550: PCE (PC emulator card?) \____ these are half-height

I think so. I don't have this in my system.

>         140K05980: LPO (printer port)      /     cards that share a slot
>         140K24340: IOP-2 (ethernet, floppy, keyboard, comm, printer)
>         140K24590: MBP-2 (no ports on this card)
>         <blank slot>
>         140K24580: DCM-2 (display port)
> 
> Other hardware:
> 
>   2 Xerox mouse pads
>   2 mice
>   1 keyboard
>   2 floppy enclosures (one with a drive in it, one with just air)

These are electrically just cables to sort out the DC37 plug back to the 
34 pin edge connector and 4 pin power connector. There's a special 
external cable that links the DC37 on the floppy box to the DC37 on the 
IOP and to the 4 pin power outlet on the back of the PSU module.

I have 2 of these boxes. One contains a floppy drive, the other a QIC 
tape drive with a floppy interface.

>   1 extra hard drive tray (from browsing the docs, it looks like you
>                            need an ST412/ST506 if you want to replace
>                            a drive)

AFAIK it's a standard ST506-like interface, yes.

>   These computers do not come with monitors. I do not know if it is
>   possible to easily cook something up to connect standard monitors to
>   them.

Not easy at all. From what I remember, the signals are differential ECL 
signals, the scan rates aren't standard either. 

FWIW, I bought a 6805 eyars ago at a radio rally (hamfest) for 10 quid. 
The seller had no clue what it was, but when he pulled the MPB and I saw 
the 4 40 pin chips in the corner that looked like 2901s (they were...), I 
was hooked. It came with a monitor, but no keyboard or mouse. 

-tony




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