faranth: PERQ 1
faranth currently holds the record for oldest and largest computer
I own... faranth is a PERQ 1, which is a massive
350x700x650mm in size
(although the Technical Overview boasts of the machine's "small size and
low cost"...)
The PERQ1 has a 14 inch hard drive and an 8 inch floppy. It's got a portrait
monitor, 768x1024 pixels in size, which is pretty impressive for a machine
designed in 1979! One of the nicest things about this machine is the
architecture; it uses a soft-microcoded CPU, so you can write new microcode
to give the CPU a different instruction set.
10Mb/sec ethernet was standard on later PERQs, and was an option for the PERQ 1,
but faranth doesn't have this. It does however have the GPIB parallel
instrument control bus, which could theoretically be used for networking.
TCP/IP code is available for the PERQ running POS, but assumes 3Mb/sec or 10Mb/sec
ethernet hardware.
See also my general PERQ page.
Acquisition
- Date: Michaelmas 1996
- Cost: Nothing
faranth was acquired from somebody in Wales (who was fortunately
willing to bring it over to Cambridge...) who said they'd had it for
a number of years. It is apparently originally from Oxford
University. It was SERC PERQ number 169.
Images of faranth
Updated with some newer photos taken in 2013 with a much better quality
camera. (I can't believe I've owned this thing for over 16 years...) All
images can be clicked through for larger (600-700MB) versions.
Overall view
This is an overall view of the machine with the front, side and top panels all removed.
The various components are all attached to a pretty solid square tubed steel frame.
The 8" floppy drive is at the top, the hard disk is mounted vertically on
the left, and the right has the card cage for the CPU/RAM/IO boards sat on top of
the power supply.
CPU board
The PERQ is based on a custom logic design centred around a bitsliced ALU
and an AMD 2910 microcode sequencer. This whole board is the CPU proper.
Memory board
1MB RAM board. The RAM effectively runs slower than the CPU -- it takes several
microcycles for the CPU to say "OK, I want the data at this address; wait; wait;
OK, getting 64 bytes of data".
I/O board
The I/O board deals with talking to serial, keyboard, floppy and hard disks. There's a
Z80 lurking on here which does the work.
View of Hard Disk
This image shows the disk side of the Shugart 4006 hard disk. There are
two platters and four heads behind the translucent plastic cover. The
disk is a 14" model. The mains spindle motor can be seen at
the top right (it drives the platters via a belt). The head arm is on the left.
Closeup of Heads
This image shows the head on the topmost surface of the disk. The
central hub of the disk can just be seen to the right. I apologise
about the flash reflection off the disk cover.
Hard Disk -- Logic Side
The (mains powered) disk motor is top left, and the black plastic cover over the belt
from the motor to the spindle can be seen in the middle of the image.
The protective cover over the head motor is on the right.
Caution!
"-CAUTION- Damper movement with AC power not energized will
damage head/disk"
Parking the heads on a PERQ 1
is something of an adventure...
This page written by Peter Maydell
(pmaydell@chiark.greenend.org.uk).
