<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
Received on Tue Mar 03 1998 - 07:36:20 GMT