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Old 25th Apr 2019, 1:12 am   #172
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: MK14 schematic revisions

According to my MK14 edge connector diagram from the manual the 32 pins of that connector (top side) are numbered 1 (nearest the regulator end) to 32 (nearest the vertical resistors). Place the VDU card in its logical location next to the edge connector and the first thing you see is that the numbering on the VDU pins runs the other way. Awkward.

The other problem is that there are more lines connected to the 'b'; row than that single track you see going to b17 on the top side. Other 'b' row pins are reached by Vias coming from the track side of the PCB.

If we line them up anyway, the connections on the MK14 top side and VDU top side ('b' row) line up as per the attached diagram.

This is not as bad as it could be, with most of the VDU 'b' row control lines ending up connected to 8154 I/O pins which can then be used to drive or read them, as applicable.

The problems are the VDU 'Reverse page' input (b15) which finds itself connected to the MK14 interrupt input, and the VDU clock input (b27) which gets shorted to 0V.
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