Bit Banger was Analog modem emulator?

Tony Duell ard at
Tue Aug 16 17:51:04 CDT 2005

> That reminds me or another little machine from Motorola.  They
> called it the Educator II (and was the first computer I ever
> owned).  Their cassette interface worked pretty much the same
> way.  They toggled a pin on the PIA in software for a simple
> FM encoding at 110 baud.  Even the receive side was software.

Many microcomputer cassette interfaces are bit-banged. It works quite 
well for that application, because you know when data could be coming 
from the cassette (the user has executed a LOAD command or whatever it's 
called), so you can put the microprocesosr into a loop looking for 
transitions on the input pin.

It works less well for linking to a terminal, because you have know idea 
when the user is going to press a key :-)


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