Do-It-Yourself PDP-11 help!

From: Pete Turnbull <>
Date: Wed Feb 16 13:27:20 2005

On Feb 16 2005, 1:01, Gordon JC Pearce wrote:

> I have (plugged into the machine when I got it):
> a KDJ-11A - I believe this goes in the top-left space, looking down
> the sockets
> a Baydel B01076 card, with a couple of eproms, a console port, and a
> lead that goes to the front panel (more of which anon)
> a Fourth Generation Systems memory board, with 18 41256s on it
> an RXV21
> an RLV12
> an SCD-DHV11 board
> the backplane is labelled "General Robotics Corp", and "P/N
> a couple of other boards that weren't in the machine, which are:
> a WDC11-C board
> an M8044 memory board, 32Kx18 bit
> The little front panel has a key switch that switches the mains on
> off, a reset button with a "DC ok" LED, a Run/Halt switch which is
> broken, and a three-position switch marked "L.T.C. on/off". With
> switch up, the LED above it lights up. "Local Terminal Console" is
> best guess so far.

Line Time Clock. There's a bus signal called BEVENT which is driven by
a square wave derived (usually) from the mains supply at either 50Hz or
60Hz, which generates an interrupt used for a real-time clock. The LTC
switch disables the BEVENT line on the bus.

> Do the cards need to go into specific slots on the backplane? If I
> google for anything in this machine I get lots of sites offering to
> me cards, but very little in the way of real information.

Not really, but to get a properly running system you usually need to
make sure the grant chain is intact; ie there are no gaps between
cards. You indicated elsewhewre that this backplane is serpentine, so
check that there's a card in each logical position between CPU and the
last card. It's also normal to have the memory right after the CPU,
console and sometimes other serial ports next, then disks and tapes,
and finally bootstrap/terminator.

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Wed Feb 16 2005 - 13:27:20 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:38 BST