I have a DE V3 board that has had considerable acid damage, this has been repaired........More of a thread to come later that will hopefully help someone?
But am stuck on the DE pinwiki page 29.
Just need some clarification please?
Under the heading 'the blanking circuit explained' 2. states that pin 4 of the 6821 should be high, yet underneath regarding the 555 timer 2. it states that pin 4 should be pulsing.
The blanking circuit explained
1.A properly executing CPU will send data to the display 6821 PIA at 11B at regular intervals (every 2.8 msec).
2.This action causes PA2 at pin 4 of the 6821 to go high. The schematics call this signal "TG".
When operating properly, the pins of the 555 timer will behave as follows (pin number, logic signal)
Pin 2. pulsing at the same rate as the 6821 PIA at 11B, pin 4
So for testing purposes this to me reads as conflicting, but on the other hand i may be missing something hence the post.