PDP-12 Restoration at the RICM

Michael Thompson michael.99.thompson at gmail.com
Tue Jun 16 18:29:37 CDT 2015

> Date: Mon, 15 Jun 2015 19:42:42 -0400
> From: Michael Thompson <michael.99.thompson at gmail.com>
> To: cctech <cctech at classiccmp.org>
> The M452 creates a 220 Hz clock for the TTY transmitter and a 880 Hz clock
> for the TTY receiver.
> The M405 for the DP12-B serial port generated a clock that is 16x the baud
> rate which is then divided by an M216 module.
> Michael Thompson
Just to prolong this discussion...

The PDP-12 came to us with an M452 for the 110 baud TTY console and a
home-made adjustable baud rate module for the second serial port. The
adjustable baud rate generator was made by the original user of the system
in the early 80s, and is just a crystal, rotary switch and a Fairchild
4702. I ordered a replacement Intersil IM4702 so we can repair the module.
The original owner doesn't remember ever having an M405 for the second
serial port.

Michael Thompson

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