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.


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

PERQ with case removed
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

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

CPU 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

CPU 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

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

view of hard disk 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

view of disk logic boards
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! : head motor cover
"-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).