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What are these wires for? (130 XE)


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They utilize an unused gate on the LS08 AND gate to

provide a delayed or boosted chip select signal to

GTIA. Some with, some without and I doubt any board

is using the unused gate of the LS08 from the factory.

 

I still contend this is just busy work. Not ever needed

in the first place and no harm or foul if done or

left undone. Why?

 

PCB repair crew left not busy would be having food fights

and reading novels on company time. So you pile perfectly

good machines to the ceiling next to them and tell them

to get busy doing this 'mod'. When one shows up off the

line that is actually broke and needs repair it gets

pushed to the next one done, otherwise you know what you

will doing all day long.

 

Similar useless wiring 'mods' are done to the XL line too.

 

On the underside of 'wired' boards there is a cut trace

from the MMU pin 15 to GTIA pin 32, So if you want to pull the wires,

you'll have to restore that trace on the bottom. Or as

one guy put it, you have no video.

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No edit for some reason.

 

Wrong chip above, pin 15 of U2 LS138 which is doing

part of the MMU decoding is where GTIA chip select

signal comes from. And they do put this fix in on modern

boards to my surprise. Might be a little more to

this story than post #31 would point to.

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