Wms System 4 CPU board upgrade?

kencinder

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I purchased what I thought was a System 3 CPU board awhile back, with the intention of upgrading it for my Phoenix. I am going to use IC14 instead of IC21/22.

I pulled it out tonight to do just that, and it would seem that it is a System 4 board that was running Sys 3 roms (Hot Tip), at least according to Pinrepair it is going by the numbers on the board, and the fact IC14 is already present (but unused until now).

According to Pinrepair, System 4 boards already have the modification done, but looking at my board it doesn't appear that is the case.

Do I need to do this mod at IC15, or is there something I am not aware of going on here?
I would imagine I do, since the Hot Tip roms were in IC21/22 and that's supposed to be an address select line...but I don't want to go cutting a trace if I don't need to or shouldn't.

http://www.pinrepair.com/sys37/index2.htm#cpuupgrade


 
It's a bit of a confusing statement when he said that "the modification is already done", because it's not like they modified an existing board. The board layout in the system 4's was printed differently.

Looking at the photos of a system 3, compared to yours, you're good to go already. The trace that you would have to cut and redirect isn't even present on your board, which means that IC14 is ready to use without modification.

-Hans
 
You're right, I thought it was the trace beneath the 3rd pin, but looking at his picture again it's not.

Was hard to spot, as his picture is kind of grainy and the board looks very dirty.

Seems I just keep getting luckier too, I pulled the driver board to do anything I need to it as well, and it's a System 7 board that's already done.
 
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