1st stage loader for IMSAI - need ascii to binary conversion

[Tony Duell]

>     Easy path: two tone detectors, going to a microcontroller who store the 
> data read from the tape and send it in RS232 way. A very simple AVR 
> microcontroller can do that ;o) 

Argh!. I grew up learning to design solutions to problems, rather than 
throw microcontrollers at them in the hope they'd go away.

For the standard 1200/2400Hz cassette tones, there's a very simple 
circuit using a pair of monostables (one-shots) -- IIRC a single 74LS123 
chip will do -- that does the decodning from the tones to a bitstream. 

BTW, if you've got tone detectors (presumably one tuned to the '1' tone, 
the other to the '0' tone), why do you need a miocrocontroller to turn 
the output into a bitstrea?. A few logic gates is a lot simpler.

-tony