Hey Guys, after days of trying to work this out, I gotta see if anyone has fresh ideas...
I have PCB Set 1 and PCB Set 2, both System 6 right? Im using Leons test Rom so we're pulsing high low every second...
I know Set 1 is OK, and know that the driver pcb from set 2 will happily high/low pulse on the 6821s so everything slooking good...
Now plug either driver board into set 2's MPU pins 2-17 of both IC5 and IC10 6821 PIAs show either high or low but not pulse or activity - the data lines are happily H/L Pulsing!
Its not the 6821s or indeed therefore a driver pcb issue...
testing the pins on the connector of the MPUs from 1-40 Im getting the same activity on the probe so it LOOKs like both pcbs are outputting the correct signals on the connectors (all replaced btw!)
So, I cant see what the issue is - maybe a timing on these pins? Its doing my nut in and every day the Slam looms closer!
I guess i need to repat the excercise of reading the pins 1-40 when the drivers are connected on both pcbs next? Or does someone know what makes the 6821 pins 2-17 toggle and pulse?
Thanks in advance I'm completely lost!
R!
I have PCB Set 1 and PCB Set 2, both System 6 right? Im using Leons test Rom so we're pulsing high low every second...
I know Set 1 is OK, and know that the driver pcb from set 2 will happily high/low pulse on the 6821s so everything slooking good...
Now plug either driver board into set 2's MPU pins 2-17 of both IC5 and IC10 6821 PIAs show either high or low but not pulse or activity - the data lines are happily H/L Pulsing!
Its not the 6821s or indeed therefore a driver pcb issue...
testing the pins on the connector of the MPUs from 1-40 Im getting the same activity on the probe so it LOOKs like both pcbs are outputting the correct signals on the connectors (all replaced btw!)
So, I cant see what the issue is - maybe a timing on these pins? Its doing my nut in and every day the Slam looms closer!
I guess i need to repat the excercise of reading the pins 1-40 when the drivers are connected on both pcbs next? Or does someone know what makes the 6821 pins 2-17 toggle and pulse?
Thanks in advance I'm completely lost!
R!