OT: how big would it be?

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Wed Oct 20 13:08:31 1999

On Wed, 20 Oct 1999, daniel wrote:

> Allison: You worked on transistor 8s? How did they impliment the 20mA
> current loop. I posted a message a while back about how it *was* set up in
> this cpu. The schematics of a PT08 show nothing other than one TTY line
> right into the receiver board.

It was a transistor level converter from logic levels to 20ma. the
circuit for wich is fairly simple. It was the serial/deserial hardware
that ate a few boards. As in the case of the most 8's the tx/rx data was
directly to the Accumulator. There were designs that would stall the
machine while the bits were serialized/deserialized and written one by one
to Acc. Saved registers but the cpu was stopped for about 1/10th second.

Allison
Received on Wed Oct 20 1999 - 13:08:31 BST