So Iwas taking a closer look at the HP 1351A "Graphics Generator" I
have. It's currently in operable condition, except that it won't draw
text (apparently there's something wrong with the character generator,
the :TX commands do nothing at all). I was surprised to discover that
the 1351 (c. 1981) doesn't containa microprocessor or microcontroller of
any kind -- all parsing of the command language it supports is done in
hardware (TTL). (The service manual contains this gem: "The 1351A only
accepts commands listed in this manual and in the Operating and
Programming manual. Any others, especially those mentioned above will
'lock up' the 1351A such that it will have to be re-initialized...")
The earlier HP1350 'Craphics Translator' is similar. It contains no
microprocesosr (which is odd, as HP were certainly using them at the
time). What is (to me) even stranger is that it's essentaily 'random
logic', it is not designed as a processor (built from TTL) or anything
like that. Very odd.
In the 1350, the chracter geenrator is sepeaate daughterboard, the unit
will work without it, but obviously can't then handle text comands. It's
been some time since I've been inside my 1350, but from what I rememebr
the chracter generator is a lookup table of vectors todraw each chracter
(unlike the DEC VT11, say, which scans a little raster at each chracter
location and uses a conventioal bitmapped chracter generator ROM).
At any rate, this reminded me of something that I'm prettysure I read
here on cctalk years back, but I can't seem to find any reference toit
anywhere; there was a computer designed at some university that ran an
interpreted language (I'm pretty sure it was BASIC), on the metal-- that
is, much like the 1351A and its vector description language, this
machine's hardware parsed BASIC program text and executed it directly,
rather than implementing some machine language.
Depends on what you mean by 'on the metal'. There have been several
machines that interpret high-level languesesa at the microcode level, I
think Wang made one for BASIC. But I've never heard of a non-microcoded
machine that did that. Was there one?
-tony