Re: 1541 -> 2031

From: Frank Kontros (
Date: 2000-09-11 10:28:20

Marko Mäkelä wrote:

> One thing that could give some trouble-shooting hints is the voltage I
> measured from the IEEE-488 connector.  When I powered up the disk drive
> but left the PET turned off, there were some 1.4 volts between ATN and
> GND.  After turning on the PET, the voltage rose to some 3.3 volts.
> Issuing a floppy command lowered the voltage (as displayed by a digital
> multimeter) by a few millivolts for one sample.  This indicates that
> something is happening on the bus.  I should take the computer and the
> drive to an oscilloscope some day.

What line drivers you used? CMOS, HCT(MOS)? Once I had similar problem
C64 and SFD-1001. The IEEE-488 schematic taken from 64'er magazin.
CMOS driver used after 6821, but only with 7406 worked properly.


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