Re: 6502 to 8501: new details

From: Marko Mäkelä (
Date: 2002-02-21 22:30:44

Daniele Gratteri wrote:
> If (and when) you will have some free time, I'll be happy if you can
> investigate why the Datassette doesn't operate properly with the CPU module
> installed. After all, the schematic is yours! Maybe I should publish it so
> who wants to try it can do the thing?

What if you added a pull-up resistor to the CASSETTE WRITE line?  I had 
to do the same in the C2N232 device (for CASSETTE READ).  This is just a 
wild guess, as the Atmel AT90S2313 is a CMOS device and not an NMOS one 
like the 6522 is.  Have you measured the voltages on CASSETTE WRITE when 
recording and on CASSETTE READ when playing back the tape?  Even when 
using a digital multimeter, the voltages should read something between 0 
and 5 volts, or steady 0 or 5 volts if the circuit doesn't work properly.


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