DEC pdp 11 "R-K ABBR. BOOT P. C. Board"

[william degnan]

It should be easy enough to install on a test system, check the address
space where typical bootstraps go, see what's there, etc.  Thanks.

On Wed, Oct 7, 2015 at 4:58 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:

> On 2015-Oct-06, at 9:18 AM, Henk Gooijen wrote:
> > -----Oorspronkelijk bericht----- From: william degnan
> > Sent: Tuesday, October 06, 2015 2:26 PM
> > To: cctech
> > Subject: DEC pdp 11 "R-K ABBR. BOOT P. C. Board"
> >
> > What is the purpose of this controller?  It came with a PDP 11/05 system:
> >
> http://vintagecomputer.net/digital/PDP11-05/dec_r-k_abbr_bootPC_Board-a_front.jpg
> >
> > Printed on the controller is
> > R-K ABBR. BOOT P. C. Board 609395 Rev B
> > 802000 Rev
> >
> > I searched around, found nothing specific  Is this a bootstrap board for
> an
> > RK drive?
> > --
> > Bill
> > vintagecomputer.net
> >
> > =========
> > I am clueless too, but if you want to play Sherlock Holmes,
> > it should be possible to figure it out.
> > 20 ICs, several will be familiar in use in circuitr for the bus.
> > I'd first check whether it is intended for UNIBUS (likely) or QBUS.
> > Given the IC types you can estimate the circuit complexity.
> > If there are lots of simple gates it is just a puzzle.
> > The board has good quality machined pins, so after making pictures
> > and a drawing the location of each IC, you could pull them and
> > trace every pin, visually and with an Ohm meter. Lots of work, not
> > difficult, but very time consuming ...
> > Good for the dark evenings :-)
>
>
> IC date codes are 75/6, I guess that's just late enough to be QBUS, but
> more likely UNIBUS.
>
> Can't discern all the IC types but some speculation based on what can be
> seen: the labeled IC could be a 256*4 PROM, when a memory read-cycle is
> initiated the 74221 monostables sequence the reading of 4-bit chunks into
> the the 74175 latches to make up a 16-bit word for presentation on the bus.
> The jumpers at centre-bottom could be the base address.
> A 256*4 PROM would give a 64-word bootstrap.
>
> Easy board to reverse-engineer.
>
>


-- 
Bill
vintagecomputer.net