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.
