A500 > atk > ciabta/b irq > fail!

[8362r8]

Hi out there
Tring to fix an issue with a A500, Rev6A:


- ATK v1.18 reports two FAILs on CIABTA/B IRQ, 0 IRQs
- CIAB TOD fails as well
- DiagROM (v1.1 - don't have a newer version) reports no errors doing the corrsponding tests
- exchanging CIA A and B doesn't change anything
- playing the game "Toyota Celica GT Rally" I can see that the driving speed is very very slow, when drving with 100mph it feels like 5mph
- apart of that booting from disks and other games are running normally


Does anyone know what exactly those ATK FAILs are telling us and where I can start to look for the source of this fault?


There seems to be only few explantions about the ATK tests around.


Thanks to everyone!

[LIV2]

ATK test failure indicates that the CIA didn't trigger any interrupts when it should.
Diagrom doesn't appear to test CIA interrupts it just counts ticks & the IRQ test in diagrom triggers the IRQs using Paula if I understand correctly.

I'd check connectivity between:

CIA U7 pin 21 <--> Paula pin 16
CIA U8 pin 21 <--> Paula pin 18

[8362r8]

Liv2, Great stuff - you're the man!

U8/CIA B has a loose contact on its contact to the socket - at least on pin 21!

As I was already aiming to replace that particular socket, I will do so as next.


Actually, those sockets on this serie of 6A MBs seam to be of bad quality - previoulsy I was installing a boot selector on CIA B and recognized that they won't fit properly. After that some pin holes of the socket have been streched out.


Will exchange now the socket and let you know the results!

[Jope]

Wiper sockets often stretch out when you fit in something else than a chip. The socket itself isn't bad quality per se, but it's just not intended to take thick pins.

[hooverphonique]

Originally Posted by Jope

Wiper sockets often stretch out when you fit in something else than a chip. The socket itself isn't bad quality per se, but it's just not intended to take thick pins.

This can often be solved by putting a sacrifial wiper socket in between the motherboard and the device with pins you want to insert. It will prevent overstretching the motherboard socket wipers..

[8362r8]

Thanks for those hints!


Indeed, always use a sandwich socket between the original socket on MB and any other PCB/socket aslong not placing the original chips!


The socket is replaced and all the phanomeons are gone. ATK/CIA tests results are good again and also the funny issue with the Toyota Celica game is history.