The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
The classic 'first test' for a memory test program is to write 'own address' into each location, then read them back in reverse order.
(This is often followed by 'inverse own address')
As you say overlapping addressing will never show up on a 'write a byte, test a byte' test as you don't really know where it is putting the data.
awemawson:
I realised that I'd made a wrong assumption regarding the Data and Address bus terminations - the Data bus wasn't terminated at all ! So for the sake of completion here is the amended circuit:
Muzzerboy:
Getting there! FWIW, A12 has two 10k pullups. Is that because one is redundant or should one of them be pulling up another line?
awemawson:
I'm struggling to find two pull ups for A12, give me a clue !
The intended one is on resistor pack G pin 2.
Are you maybe confusing edge connector pin A12 with Signal A12 - I know it's a nightmare of alphanumerics !
Later Edit:
Ah found what you mean
awemawson:
The logic driving the four chip select pins on the Ram chips is a bit odd - I can't quite work out what they are trying to achieve :scratch:
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