CMD CQD-220TM problems

On Nov 7, 2011, at 2:57 PM, Glen Slick wrote: So if anyone is at all curious about the answer to this particular quandary (which was lost long ago amidst the talk of electrocuting poor, defenseless circuit boards), the answer seems to be busted aging non-volatile storage. I desoldered the NMC9306 (Microwire EEPROM) and put a socket in so I could test it in my ROM burner. The ROM burner reads all Fs from it (I checked continuity to all pins, so it wasn't that) and can't program anything to it, so I guess the chip is borked. At least with a socket, it'll be easy to put the new one in. If I run the thing without the EEPROM in (I saw provisions for a blank/absent chip in the 8086 code, so I figured I'd give it a shot) it works! The serial port works as expected now, too. The EEPROM holds some information necessary for running, like the LUN offset and some disk/tape configuration options that I haven't work out yet (though defaults are loaded if the EEPROM doesn't come up right). Given the amount of fallback for absent EEPROMs, I should probably be able to get this thing to run without one for the time being. Of course, there's always a catch; my last remaining spare SCSI drive seems to have died in my most recent move, so I'll have to cannibalize one from one of my older Macs. Anyone know where to get NMC9306s? It's an incredibly old and terrible chip, so it's not currently manufactured, and Jameco doesn't have any old pulls. Can't find them on any arcade repair parts sites, either, which is usually my best bet. Anyone else have any usual sites for finding vintage ICs? - Dave