> > Date: Mon, 15 Jun 2015 05:01:36 +0000 > From: tony duell <a...@p850ug1.demon.co.uk> > Subject: RE: PDP-12 Restoration at the RICM (tony duell) > > > > Tony, thank you for your offer to supply replacement M452 Variable Clock > > modules for the console. We already have one jumpered for 110 baud for > the > > Teletype. The other two M452 modules should be jumpered for 9600 baud and > > 38400 baud. The second serial port uses a M405 Crystal Clock module with > a > > Do you want 3 separate modules, or one switchable, or what? > > > different pinout and clock outputs than the M452. We don't have any of > > these modules, so the three that we need should be jumpered for 110 baud, > > 9600 baud, and 38400 baud. The shipping address for the RICM is on the > WWW > > page. > > Hang on. I thought the M405 was just a crystal oscillator without a > divider. Are > you sure there is no extra division on other modules? 110Hz is very slow > for > a crystal oscillator, after all. > > -tony >
The M452 creates a 110 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
