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

Dave McGuire mcguire at neurotica.com
Tue Feb 26 16:53:38 CST 2008

On Feb 26, 2008, at 2:57 PM, Tony Duell wrote:
>>     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.

   There's still quite a bit of design involved.  Microcontrollers  
aren't "automatic", as I'm sure you're well aware.  A microcontroller- 
based design is every bit as valid and honest as an all-discrete design.

> 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.

   Well, Chuck said it best, but I'll add this: You get fewer  
components, lower cost, easier maintainability and tweakability,  
increased flexibility, the possibility for a reusable design...how is  
this a bad thing?


Dave McGuire
Port Charlotte, FL

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