kencinder
New member
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


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

