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Timbucus · 16th May 2020, 2:29 pm

Well I cannot find why this damm thing is holding all except D5 and D4 low - that will mean the system is executing XPAL 00 so the accumulator will become the low byte of the PC (which is already advanced to the next instruction). If I force D4/5 low with the switches it executes a HALT as the D7 light comes on on each tri-state pause between steps as it should with a halt instruction - so it is just the memory issue to solve now I think and the thing will work.

16th May 2020, 2:29 pm	#143
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,364	Re: Recreating the Bywood Scrumpi Well I cannot find why this damm thing is holding all except D5 and D4 low - that will mean the system is executing XPAL 00 so the accumulator will become the low byte of the PC (which is already advanced to the next instruction). If I force D4/5 low with the switches it executes a HALT as the D7 light comes on on each tri-state pause between steps as it should with a halt instruction - so it is just the memory issue to solve now I think and the thing will work.