Re: Real Time Clock on Cassette Write/Sense lines

From: Jim Brain <>
Date: Sat, 11 Feb 2012 11:57:27 -0600
Message-ID: <>
On 2/11/2012 11:20 AM, Gerrit Heitsch wrote:
> On 02/11/2012 06:02 PM, Jim Brain wrote:
> If you want to use the motor line for I2C, but still be able to use 
> the tape drive, why not set up a low pass filter on it so the motor 
> line that the tape drive sees only gets activated if there is a true 
> static signal on the line and not the I2C data or clock.
>  Gerrit
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I'd prefer not to use the MOTOR line, due to the voltages, the possible 
skew, and the upper limit on switching speed due to the voltage division 
used (resistors).  As well, it's rather substantial in amperage, so the 
parts needed to low pass filter that signal are not trivial.

I will admit that using MOTOR for the SCK line and WRITE for READ/WRITE 
has some merit, but I worry that if someone leaves the tape in RECORD 
mode, I will send data to the datasette when cycling MOTOR and applying 
signals to the WRITE line.  Using WRITE/SENSE wtihout motor minimizes 
that concern.


Jim Brain

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Received on 2012-02-11 18:00:23

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