Cassette Interface Assistance

Jim Brain brain at
Tue Feb 28 12:39:53 CST 2017

On 2/28/2017 11:56 AM, Chuck Guzis via cctalk wrote:
> On 02/28/2017 09:42 AM, Seth Morabito via cctalk wrote:
>> Synertek used an LM311 (an LM358 would work just fine) to build a
>> comparator circuit. I _think_ you could use this exact circuit to
>> take the analog output from the CoCo and turn it into a 5V sqauare
>> wave.
> I don't know a thing about the CoCo cassette format.  I know that back
> in the day when things like the KC standard were the rage, a NE567 PLL
> was considered the cat's whiskers for data recovery.  But again, I don't
> know what the CoCo cassette standard looks like.
I admit my previous cassette format knowledge is Commodore based, where 
they basically shoved a 5V digital signal to the cassette deck, and 
expected the deck (which they produced) to handle it. Thus, interfacing 
with it is a digital exercise.  But, I am not picky on circuitry, so I 
will take a look.  Any pointers to a schematic?
> Also, you may want to look at the IBM  5150 (PC) cassette circuit.  My
> recollection was that it was pretty robust, even if few made use of the
> facility.
I will do so.  Right now, a success, even if it's not a final state 
option, would be helpful.  I had this great idea, but held off on it for 
a few weeks because I suspected I'd end up in this state...
> --Chuck

Jim Brain
brain at

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