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cmjones01 · 3rd Jan 2018, 9:24 pm

A quick test would be to locate the ribbon cable joining the CPU board and display board and disconnect it, and see if the behaviour of the display changes. The 'junk' visible on the screen may be the random data which is in the display board's RAM at power up, or it may be getting written there by the CPU. In any case, a change in the display contents when switching on with and without the display cable connected gives us a clue that the CPU is at least trying to do something.

Chris

3rd Jan 2018, 9:24 pm	#30
cmjones01 Nonode Join Date: Oct 2008 Location: Warsaw, Poland and Cambridge, UK Posts: 2,681	Re: 8085 processor questions A quick test would be to locate the ribbon cable joining the CPU board and display board and disconnect it, and see if the behaviour of the display changes. The 'junk' visible on the screen may be the random data which is in the display board's RAM at power up, or it may be getting written there by the CPU. In any case, a change in the display contents when switching on with and without the display cable connected gives us a clue that the CPU is at least trying to do something. Chris __________________ What's going on in the workshop? http://martin-jones.com/