> sounds to me exactly what older computers (tandy, trs80, etc) did to
> access programs/data stored in tapes.  You just plugged the tape
> recorder to the back of you PC and that was it.
> 
> 90 bytes/sec = 720 bits/sec, less data than the older 2.4 Kbaud
> modems used to handle.  I think you can easily use a pic or some
> other mcu connected to a nice set of ad/da converters do to the job
> for you, or at least one of these new generation DSP chips from
> Microchip, TI or Motorola

The Commodore 64's Datasette amplified and logic-squared output
goes straight to the 6526 CIA /FLAG pin, which is an edge-sensitive
input like the PIC's PortB.0. From memory that signal was at least a
volt or two either side of 2.5V. Some commercial tapes were weaker,
probably high-speed copied, but the signal still managed to cross the
logic levels on /FLAG. Also the program was written on to tape twice
and a verification done between the two loads

BTW, disk input processing through the serial port was based on tape
processing s/w and terribly slow until someone came up with a turbo
wedge for the 1541 drive routines. The 6526, a wonderful little IC,
was capable of much faster throughput than the conservative storage
density of original tape/disk. Later tapes/floppies installed a turbo first
and then were able to use much faster transfers from denser data


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist