11 Jun
1998
11 Jun
'98
12:35 p.m.
How does this soft-microcode thing work? Doesn't it imply that there
is some kind of "sub-microcode" needed to load and process the soft
one? Or was there a completely separate storage subsystem that booted
first (which would essentially make it two computers)?
Also, where was the microcode stored? Could you upgrade special
"microcode cache" to store more complex microcode? Sounds pretty
unusual!
and with a somewhat interesting design.
The PERQ 1 was first sold in 1979 for (I think) $30000. For that you
got
a personal computer (!) with about 1MIPS of computing
power. You also
got
a megabyte of memory, a bitmapped display (768*1024
points, portrait),
a blitter, a 20 bit CPU, a Z-80 based I/O processor, a hard disk, a
pointing device (normally a Sumagraphics bit pad 1), etc. Options
included networking (ethernet came out pretty soon after the first
machine) and a laser printer.
All 'classic PERQs' (everything apart from the PERQ 3a) have a
soft-microcoded CPU that loads the microcode (and hence the instruction
set) from disk when the machine boots. Writing your own microcode is
fun.
The PERQ 1a introduced the 16K CPU board with 4 times
the control store
and other improvements (multiply/divide support, indexed addressing of
the _registers_) over the original 4K board.
The PERQ 2's all had a revised I/O board with an extra serial port,
battery-backed real time clock and ethernet as standard. The
multitasking
I/O software was only present on these boards AFAIK.
You could add the
same I/O option boards to the PERQ 2's, so in theory you can have a
PERQ
2 with 2 ethernet ports.
Older PERQs were 20 bit. The rare PERQ 2T4 was 24 bit.
If you're interested in finding out more, look at Bob Davis's PERQ web
page (a web search should find it). There's a number of text files
there
which explain a few things. There's also a somewhat
dead Usenet group,
alt.sys.perq, which would love some on-topic messages again :-).
universities,
here on the rebellious side of the Atlantic? (I
know _nothing_ of
They were a USA machine (3 Rivers Computer Corporation). But some bits
of the design were done by ICL in the UK, and they were sold by ICL.
They were also one of the standard machines supplied to UK which may explain why they're more common over
here.
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these machines beyond your messages, if I saw
them advertised the
references went into brain cells that have been foully murdered).
Ward Griffiths
-tony