<I have acquired an old "kit" computer, circa 1977. The CPU has a = <trademark like a double script N, slanted to the right, with one = <superimposed on the other. Most of the other 10 or so smaller chips <have = the same mark. National Semiconductor. <Adjacent to this is the number 804 (the CPU ID?) Other numbers are = <ISP-8A, /500D and SC/MP. there is a clue in the markings. The part numebr is ISP-8A/500D, aka SC/MP. The (D) in the part number says ceramic package. The part is implmented in an older P-channel MOS 3 voltage technology. A faster and single voltage Nmos version was about a year later (ISP-8A/600). <It is the size and shape of a Z80 or 8085 That means it has 40 pins. <Anyone have any idea what this is? That is the National Semiconductor SC/MP cpu on likely a evaluation kit board. there were two versions one had a calculator like terminal and the oter used rs232/tty interface to a terminal. The rom (5204) was a very small 512byte monitor. It was a an interesting cpu though that version was SLOW at 2-10uS per instruction. I like to collect these(SBCs) as they are interesting though often not very useful as implemented. Allison