Bit banger /analog modem

vrs vrs at
Sat Aug 20 23:30:55 CDT 2005

> There is a sample of code in the PDP-8 programmers handbook for doing 
> bit banging on an -8.  While many machines used hardware to do this
> it was enough hardware (easily done with out a uart) to warrent another
> board and represents cost. The trade was using a little of the CPU cycles
> to dothe IO in software.  For system near the bottom dollar wise this 
> can save a few bucks. The real question is is it worth 1-10% of the 
> cpu cycles for IO, and how much IO is needed?

Was there ever an OS for the PDP-8 that used the DL8 natively, as 
opposed to shipping the data to a PDP-10 or the like?

Or does it count even if the bit-banging was done on a mini, but for 
a larger computer?


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