SE/30 ROM SIMM diagram?

dv-

Well-known member
Cleaning up a bombed SE/30 and there was enough gunk on the ROM that I took it apart to clean it. (As well as ordering a new simm socket for it.)

I damaged/tore one (1) solder pad on it, which is actually good for me, and I can bodge it easily enough but can’t figure out where it’s supposed to go. The corresponding pins on the other chips don’t seem to connect to anything (no connectivity to any pins, grounds, other components, etc.) and when I had the chips off, I couldn’t see a trace coming off of the missing pad.

Anybody know where this pin is supposed to go? (Upper right of photo, I guess pin 1?)
 

Attachments

  • IMG_2795.jpeg
    IMG_2795.jpeg
    1.5 MB · Views: 20

zigzagjoe

Well-known member
Cleaning up a bombed SE/30 and there was enough gunk on the ROM that I took it apart to clean it. (As well as ordering a new simm socket for it.)

I damaged/tore one (1) solder pad on it, which is actually good for me, and I can bodge it easily enough but can’t figure out where it’s supposed to go. The corresponding pins on the other chips don’t seem to connect to anything (no connectivity to any pins, grounds, other components, etc.) and when I had the chips off, I couldn’t see a trace coming off of the missing pad.

Anybody know where this pin is supposed to go? (Upper right of photo, I guess pin 1?)
Entirely possible it's a NC, or used only for programming. A 1Mbit (128 KByte) mask ROM chip only needs 29 pins (pwr, gnd, OE, CS, 8 data, 17 address), and that chip has 32. Programmable ROM chips will require at least one more pin, but still have at least 1 NC (probably 2) when installed in the module.

Easiest way to find out would be to try and see if it works. I'm not aware of any schematics for the apple simms though.
 
Top