The headquarters and factory were in the Sorrento Valley, although their mailing address may have been San Diego. I visited their offices once. I supported a DSC Meta-4 for several years, about 1973 to 1976. It replaced an IBM 1130 which it emulated exactly, but was 10 times faster when running IBM 1130 FORTRAN IV programs. It was an elegantly simple machine. The micro controller was truly a RISC machine, I think it had a 3 bit op code, 8 instructions. Yes it had the set/clear memory protection bits. The memory arrays in IBM 1130/1800's were 18 bits ... 16 data bits and 2 parity bits for an 1130 and 16 bits, one parity bit and one memory protect bit for the 1800. Yes it was a type of capacitor Read Only Storage with a read cycle of 90 ns. The 1130/1800 addressed 32K words, but the DSC Meta-4 had a feature so that you could load 64K or RAM, then context switch between two 32K banks. In this manner they developed a multi user 1130 timesharing system. The timesharing control system was in the upper 32K and it swapped out 1130 users. If you had a fixed head disk attached, a feature available only on the DSC Meta-4, not the 1130, you could swap out the whole 32K in some ridiculously short time, like 50 ms., then swap in another 32K user in 50 ms. and pick up where they left off. It really worked, we attached 8 dumb terminals to it and had 8 simultaneous 1130's running for less than the price of a single IBM 1130, and since it was 10 times faster than an 1130, each user could be running at about the same speed as an 1130, if they were compute bound ... not usually because most of the users were pounding the keyboard editing FORTRAN code and compiling. It worked well until we replaced it with a DEC SYSTEM-20 which was 10 to 100 times faster still ... at about the same price. I still have the manuals for the Meta-4, even though I was dumb enough to get rid of all of my 1130 manuals. As an aside, DSC developed the line of National Semiconductor IBM Mainframe clones that are now one of the Japanese lines ... and disappeared. -- Dean =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Dean Billing Phone: 530-752-5956 UC Davis FAX: 530-752-6363 IT-CR EMAIL: drbilling(a)ucdavis.edu One Shields Way Davis, CA 95616