On Sat, Apr 18, 2009 at 5:12 PM, Bob Adamson <bob at theadamsons.co.uk> wrote: Hi, Bob, I have a small amount of experience with non-DEC core... lacking a manual, I'd look for a set of three jumpers together - in that era, they tended to be solder jumpers, not modern 0.1" jumper blocks. Frequently (but not always, of course), you'll see markings on the silk screen like 0, 1, 2 or EMA1, EMA2, EMA3. Worst case, you could trace back the EMA lines from the OMNIBUS to see where they end up - there'll be some sort of circuit there to handle memory select, and I'd predict it's within an inch or two of the correct fingers on the bus. If you just can't find the jumpers, you could remove the other core and poke at memory space with the front panel. I don't recall any core under 4K, so you have 8 addresses to test. Try reading, then writing and reading. Of course, if it needs repair, that won't work so well, but it won't take long to try. -ethan