The Jim Austin Computer Collection

Vermont Drum store

This is a Drum memory store. This technology pre-dates disks. The Drum is thought to come fro a Honeywell machine. It came from the US in Jan 2009. It was made by the Vermont Research Cooperation, which no longer exists. It has 400K and 64 tracks. Date stamps indicate March and April 21^st 1970. It was a part of the collection of Plotkin.

This is a picture of the drum, visible through the holes

The copper rod is the actuator to push the heads onto the drum

The store has electronics on the top for controlling the motor and has an actuator that pushes the heads on to the drum only after a delay controlled by the round knob on the unit. There is a switch on the drum hub to actuate the heads to the disk. There is a small rack that has the amplifiers for the heads. The 64 tracks are read by 5 separate heads. The Unit could have up to 9 heads, as shown by the missing spaces (where the drum can be seen). The connectors are below the drum.

This shows the heads.

On disks there is one movable head. The great thing with drums is the heads remain fixed. Each reads one stripe of data around the drum.

Specifications from its label:

Type 1004
Serial Number 1780
Tracks 64
RPM 3489
Code A
Motor Induction
HZ 60
Amps 1.55
Phase 1
Diameter 10 inches.
Volts 117

"Rotating Magnetic Memory Drum, Vermont Research Cooperation, North Springfield, Vermont, USA"

There is little information on these drives around. If you have any please mail me.

Could be the same as used in the HP 2774A drum memory, which also had 400K memory.

Quote from HP computer museum

"HP also introduced drum memory in 1968. The 2773A (priced at $30,000) provided 393,216 words of memory with a transfer rate of 120K words per second and an average access time of 8.7 ms. The 2774A was priced at $36,500 and provided 786,432 words of memory. The 2775A was priced at $61,500 and provided 1,572,864 words of memory. The 2773A and 2774A were each expandable to the next level of memory capacity. These products were made by Vermont Research Corporation"

Note the HP manual says the 2774A is 400K memory, this quote is slightly incorrect. It could be that it could have extra heads fitted.

This shows the top, with the switch to push in the heads

A close up of the drum and the head wiring

The black thing is the timer to allow the drum to spin up before actuating the heads