I was thinking about a diagnostic test clip for 74 series logic chips. (As one does ![:)]( "Smile")
) Not specific to acorn computers - but 8-bits in general.
I wouldn’t imagine that these are the first time these thoughts have been had - so I thought I’d ask if there was any projects out there that people know about, or clear drawbacks that I didn’t realize.
The general idea is to test the 74 series ICs in circuit. Then if problems are found see if that IC or ones it’s connected to should be desoldered for further testing…
One thought is that the power could be on to the mother board, hold the cpu reset low (& possibly something to hamper the video chip - Eg hamper the clock?). Then attempt to test the 74 series chip in circuit via a test clip & drive the IC through some unit tests (like the TL866 can do). This could probably be extended to testing ram as well.
The second thought is with the power on to the motherboard, snoop the signals on the 74 series IC and flag if the IC’s output doesn't conform to the expected logic.
I could imagine that logic analyzers might have this second feature already? (Ie you tell it what chip it’s snooping and it tells you if something is not right)
Anyhow, I thought I’d ask you guys for your thoughts / knowledge of existing things out there…
Cheers
Mike
) Not specific to acorn computers - but 8-bits in general. I wouldn’t imagine that these are the first time these thoughts have been had - so I thought I’d ask if there was any projects out there that people know about, or clear drawbacks that I didn’t realize.
The general idea is to test the 74 series ICs in circuit. Then if problems are found see if that IC or ones it’s connected to should be desoldered for further testing…
One thought is that the power could be on to the mother board, hold the cpu reset low (& possibly something to hamper the video chip - Eg hamper the clock?). Then attempt to test the 74 series chip in circuit via a test clip & drive the IC through some unit tests (like the TL866 can do). This could probably be extended to testing ram as well.
The second thought is with the power on to the motherboard, snoop the signals on the 74 series IC and flag if the IC’s output doesn't conform to the expected logic.
I could imagine that logic analyzers might have this second feature already? (Ie you tell it what chip it’s snooping and it tells you if something is not right)
Anyhow, I thought I’d ask you guys for your thoughts / knowledge of existing things out there…
Cheers
Mike
Statistics: Posted by mikeh_nz — Thu Mar 14, 2024 5:15 pm