Computer Hardware

Punched Paper Tape

This is an example of a computer programme stored on paper tape.  The tape was fed through the reader by the line of smaller tractor holes.  

The programme on the tape is a 'Double precision signed multiply subroutine' and is dated 1965. It was written for Digital Equipment Corporation's PDP8 computers.

In the 1970's Punched Cards were commonly used to store data and programmes. An example of a punched card is shown right.  It not shown to scale and the card actually measures just over 8 x 18 cm.

Core Memory

A close-up picture of ferrite Core Memory beads is shown on the right.

Core memory was a common form of electronic memory in the 1970's and earlier. It is made up of small ferrite beads. These beads can be magnetized and demagnetized individually. They are wired up on a matrix of fine copper wires like a tapestry. Each bead has three wires through it: Row, Column and sense wires.  The sense wire was required to check if a location bead was written to or read.  Both actions changed the magnetization of the bead. Therefore, if the location was read it needed to be rewritten.  Interestingly this type of memory is non-volatile. It is also where the processor crash term 'Core-dump' comes from.  This type of memory was very expensive. The circuit board, this image was taken from, had a total memory of 16Kbs and is thought to be from an 'Argus' computer.  Core memory was never used in small computers.

Alpha micro processor

The Alpha processor was manufactured by Digital Equipment Corporation in the 1990's. It was a RISC (Reduced Instruction Set Computer) processor and it had the fastest clock speed at the time.  The picture shows the underside of the processor with it's pin connectors. The metal lid has been removed so that the processor silicon and lead frame are also visible.  

Winchester / Hard Drive disks

The picture shows how disk sizes have reduced over time but the storage capacity has increased at the same time. The largest disk (14" dia) in the picture has a capacity of 10Mb and dates from the early 1970's

     'Click' here to see inside.     

Removable Floppy   

The now almost redundant 'Floppy' disk also shrunk in size from the original 8 inch shown here. Both disk types store digital information by changing the magnetic property of the coating on the disk. A small read/write head uses a coil to either write or read the information stored on the coating.  One point to note is that digital ones and zeros are not recorded directly on to the disk as magnetic media cannot record DC levels.

Laser Pinter

The scanning infra-red laser assembly from a laser printer and cover warning label are shown here.  The laser assembly can be seen at (1) and at (2) is the multi-surface scanning mirror. The scanning beam emerges through the lens, seen here at the bottom of the picture.