Fat 40

[Gary C]

So, progress so far

IEEE faulty, new UD2
Reading disks faulty, new UN5

Drive now reads and writes to a formatted disk fine, BUT it wont format one itself.
How odd.

 

[Agent Orange]

So, progress so far

IEEE faulty, new UD2
Reading disks faulty, new UN5

Drive now reads and writes to a formatted disk fine, BUT it wont format one itself.
How odd.

Possibly a mix up with "FORMAT" not being compatible with "SYS" or system?

 

[Gary C]

Not on a commodore

The DOS is built into the drive itself. You just give it a simple text command N and the drive number then it does all the work.

However, I'm now getting some errors when writing. Short programs seem to write ok, but as I started to fill the disk it threw up an error.

So close its annoying me now.

 

[Agent Orange]

Not on a commodore

The DOS is built into the drive itself. You just give it a simple text command N and the drive number then it does all the work.

However, I'm now getting some errors when writing. Short programs seem to write ok, but as I started to fill the disk it threw up an error.

So close its annoying me now.

My bad, got in late on this thread.

 

[Gary C]

Still testing, but I have noticed something.

Data comes out of pin 10 of a 74LS02. On the working digital board, the signal line has a DC offset but on the non-working board, the pulses start at 0V but don't go as high. However the actual pulse shapes look the same. I know that it can write to a formatted disk (though it does throw some errors) so its doing something and everything from the ribbon cable to the disk works fine so its something on the digital board.

Odd

Wonder if its something supply side ?

 

[Gary C]

Really odd. Data to the disk drive goes via UH2 and comes out on pin 10 with an odd offset.



When I look at the other four gates in that chip on the working board I can see the same signal on pin 5 and on pin 4 of the inverter UL2 BUT not on pin 3 of UL2 (which is the input to the inverter). According to the diagram and visual inspection, there is nothing else that feeds this junction. So either the 74LS02 at UH2 is acting really odd or something else is going on.


I want to know what's going on as the non-working board does not exhibit this phenomenon.