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CBM PET 3032 STRANGE BOOT

daver2 said:
Ok,

Can you change Nivag's board and set the ROM E link ON (to enable Nivag's PETTESTER code).

Then swap the ROM in socket UD7 for your PETTESTER EPROM.

Give it a run...

What we are going to do is to checksum the PETTESTER ROM in socket 'd'.

The PETTESTER code will think that there is a 4K ROM in UD7, so it will attempt to check it twice. I will have to compensate for that if I can.

Can you ensure the 'd' checksum that is displayed is stable. If it isn't, we can't use this test.

Dave
Click to expand...
 

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Something doesn't quite add up (literally)!

You didn't state whether the checksum was stable again...

Can you remove your PETTESTER EPROM from UD7 and run the test again with socket UD7 empty please.

Is the checksum stable with nothing in UD7 or not?

Dave
 
Ok,

So this doesn't make sense to me I am afraid.

7800/2=3C00.

3C00+75DD=B1DD (not 51DD).

Ok,

Can you remove the PETTESTER EPROM from socket UD7 and put the original PET BASIC ROM back in UD7.

Then remove the EDIT ROM from UD8 and take a high-quality, close-up photograph of the UD8 socket (with some good-quality illumination) and post the photograph please.

Dave
 
That UD8 EDIT ROM socket us knackered!

Can you see why?

Compare it with a new IC socket of the equivalent type...

Dave
 
Yep; and I may be able to see a few other pins (although perhaps less clearly) where there appears to be a gap between the contacts that grip the pin of the IC.

If this is the case, this socket is toast I am afraid. I can also see significant damage to the plastic of the socket around pin 1. I suspect this to be because you are using a screwdriver (perhaps) to remove the ROMs? With the constant insertion and removal of devices from UD8 you will damage the socket. This does, of course, also apply to other IC sockets as well. You should either purchase a 'proper' IC removal tool - or use Nivag's board now you have purchased one!

You might want to check other IC sockets for similar contact damage now you know what you are looking for...

Dave
 
daver2 said:
Yep; and I may be able to see a few other pins (although perhaps less clearly) where there appears to be a gap between the contacts that grip the pin of the IC.

If this is the case, this socket is toast I am afraid. I can also see significant damage to the plastic of the socket around pin 1. I suspect this to be because you are using a screwdriver (perhaps) to remove the ROMs? With the constant insertion and removal of devices from UD8 you will damage the socket. This does, of course, also apply to other IC sockets as well. You should either purchase a 'proper' IC removal tool - or use Nivag's board now you have purchased one!

You might want to check other IC sockets fir similar contact damage now you know what you are looking for...

Dave
Click to expand...
Ok thanks so much! So now how can i do? Time to change ud8 socket again?
 
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