Wirin' up blinkenlights

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Thu Jun 8 18:17:15 2000

>Actually, I think that adding blinking lights, and switches, to any
>computer is a good idea, and, as my PDP-11s don't have lights and
>switches, I think it's time to add them... by creating a separate rack
>panel, of course. Has anyone here added lights and switches to one of
>the PDP-11s of incomplete design?

Interesting idea, a Q-bus front panel.

The address lines are present, just wire those up to lights. Various
signals are there as well. A DMA cycle can take forever so you could build
the switch register to deposit directly into memory. Decoding an address
for the switch register in the top 4K would be pretty straightforward as
well. Does anyone know if there is a defined location for it? Displaying
registers would be difficult to do "on the fly" however you could probably
force the CPU to execute a MOV Rx, #DISPLY fairly easily.

On a tangentially related subject there was a recent series of articles in
Circuit Cellar Ink on building your own CPU in an FPGA (see
www.fpgacpu.org) and it included a VGA interface (which they displayed
characters on) clearly however if you were using it as God intended you
would create a virtual front panel :-)

--Chuck
Received on Thu Jun 08 2000 - 18:17:15 BST