using new technology on old machines. Was: PDP-12 Restoration at the RICM

tony duell ard at
Mon Jun 15 23:14:58 CDT 2015

> > I am very worried that people would rather use a microcontroller than change
> > a couple of passives. Can't anyone read a schematic and think????
> The exact same argument could be made for somebody using an NE555 instead of discrete transistors to blink an 
> LED, or discrete transistors instead of vacuum tubes to blink a neon glow lamp. For that matter, I might call

Err, to blink a neon glow lamp you use _one_ resistor and _one_ capacitor and make use of the difference between
striking and maintaining voltages.

But that is not the point. The original design for this M452 baud rate clock is an RC oscillator. One that can
run at any reasonable frequency. When restoring a machine you should keep as much of the original design 
as possible. If you want to do a reversable change you should still change as little as possible. Since it 
appears you can change the buad rate just by changing a couple of passive components that's what
IMHO you should do.


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