Have a look at JP7A. It seems like it was cut open and then repaired again. Maybe someone was trying to do the 1MB CHIP RAM mod? I can't see properly on the photo but it seems that JP2 is untouched.
I've done the expansion RAM as FAST RAM mod myself. I also read about a mod somewhere that you can populate the mobo with 1MB (CHIP) and still use the 512KB expansion (as SLOW?) for a total of 1.5MB. I find that hard to belive. There are not enough address lines? Has anyone heard of this mod?
It's an interesting system you got there! I'd love to tinker with it=)
