The IBM5100 also uses the term "microcode" - but I'm not sure if that term pre-1975 means the same as what, say, Intel used it for around the x86? I've seen a glimpse into the syntax of the x86 microcode. In the IBM 5100's case, its CPU is distributed across 14 or so SLT chips - so I never fully understood how it implements its PALM instruction set. I know the two large IC on that process are two 64-byte memory things (dunno if categorized as SRAM or DRAM, or neither), mapped to the first 128 bytes of system RAM (so a high speed pass through, where that 128 bytes correspond to the registers used by each of the 4 interrupt levels). That PALM processor was developed right around the time of the Intel 4004 (late '71 / mid '72), and stout enough to run a version of APL about a year later (I see Intel made a version of FORTRAN for the 8008, or at least a claim for it in the Intertec brochures).
Anyway, all I mean is, in early 70s did "microcode" just mean instruction-set, and that changed a few years later? Or did microcode always mean some kind of "more primitive sequence" used to construct into an instruction set? -Steve On Sun, May 4, 2025 at 1:33 PM ben via cctalk <[email protected]> wrote: > On 2025-05-04 2:11 a.m., jos via cctalk wrote: > >> I recall that system had many boards, the whole "CPU" box was external > to > >> the monitor (and in the earliest versions, the power supply was also a > >> large external box). I can't really fathom creating a BASIC out of raw > >> TTL, or maybe I'm misunderstanding the approach. > > You build a processor with some TTL, and then implement a BASIC on that > > microprocessor. > > There is always this intermediate step, no machine executes BASIC > > directly in TTL. > > > Well for BASIC that is true. > The Fairchild Symbol Computer was test to just how far TTL could go. > > > Look here for an example of a processor (Datapoint 2200) in TTL : > > > > > https://bitsavers.org/pdf/datapoint/2200/jdreesen_shematics/DP2200_mb.pdf > > > > Jos > Micocoded coded machines, could likely be programed to run basic. > > Ben. > >
