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SiriusHardware · 30th Oct 2020, 2:07 am

Strictly speaking those are video LINEs you have lined up against NENIN there.

My alarm over the images in #702 has to do with the fact that those are _CE signals which should ideally only ever really be in one state or another - not like bus lines which may be driven low, driven high or tristate, so you can expect to see some odd levels on buses.

A nice feature of those scopes is the way you can freeze the image at any time and then alter the Time / division, Volts / division and horizontal position controls to zoom in on and look at a particular point in a captured waveform in more detail.

I might try writing a bit of test code (for the PIC) which runs through all valid RAM base addresses to see what happens on all of the relevant _CE pins (NENIN will need to be asserted each time I output a base address on A8-A11 so that the SC/MP does not try to use the buses at the same time).

30th Oct 2020, 2:07 am	#706
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,575	Re: Mk14 vdu Strictly speaking those are video LINEs you have lined up against NENIN there. My alarm over the images in #702 has to do with the fact that those are _CE signals which should ideally only ever really be in one state or another - not like bus lines which may be driven low, driven high or tristate, so you can expect to see some odd levels on buses. A nice feature of those scopes is the way you can freeze the image at any time and then alter the Time / division, Volts / division and horizontal position controls to zoom in on and look at a particular point in a captured waveform in more detail. I might try writing a bit of test code (for the PIC) which runs through all valid RAM base addresses to see what happens on all of the relevant _CE pins (NENIN will need to be asserted each time I output a base address on A8-A11 so that the SC/MP does not try to use the buses at the same time).