Thread: Mk14 vdu
View Single Post
Old 27th Oct 2020, 10:15 pm   #659
Slothie
Octode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
Default Re: Mk14 vdu

Quote:
Originally Posted by SiriusHardware View Post
As you might expect, the location which now changes randomly in the upper screen area is 0F31. The range of 'random' characters has the same small range as before - characters whose codes end in 'F'.
Which tells me that when the spurious writes are happening, the data bus is not being driven, as D0-D3 are pulled up to +5v with 1.2k resistors and D4-D7 are just floating. I suppose you could pull up D4-D7 with some resistors to verify this....
Slothie is offline