Subject: Re:large disk platters?

From: McFadden, Mike <>
Date: Fri Feb 21 12:37:00 2003

I think there were larger platters.

On Thu, 20 Feb 2003, Murray McCullough wrote:
> Hi Jules,
> To my knowledge the largest hard drive platter was 24". IBM the inventor
may have produced
> an experimental platter of ~1 m as a demonstration project to management
and maybe these platters
> were 'sold' or distributed to IBM employees?

In about 1976 University of Missouri Bioengineering Program acquired an "IBM
surplus image system" from somebody "unknown" out west. They sent a couple
of graduate students to pick up the system in a U-Haul truck which was very
overloaded. When we rolled the PSU down the hall on castors it left grooves
in the floor tile because of the weight. There were 3 cabinet units each 6
feet high and 5 feet wide. One was the power supply, one was the disk
controller and the other was the disk. It had a "very large" disk platter
that ran vertically, if I remember correctly they were about 3-4 feet in
diameter. Interesting noise when they spun up, kind of like turbine engine.
There were two clamshell halves that were opened to access the platter, each
track had a fixed head over it. Stored on each track was the image on a
single display station. By switching between tracks you could access
different images. There was a vacuum pump to remove the air if you opened
the clamshells to adjust the heads. Each of the display stations had an
integrated keyboard and a proximity or optical pen to select menu items.

We wanted to investigate distributing medical images rapidly throughout a
hospital. It was a one of the kind and after a few head crashes that was
the end. We then bought a Ramtek display of 256 X 256 by 8 bits instead for

It sat in a real compuer room with:
an Interdata 8/32
a PDP 11/50 running MUMPS with 2 RK05's
a PDP 11/20 running DOS-11 with 3 RK05's and a TU10.

The SEL, PDP 8 with ASR-33, IBM 026 and IBM 029 were next door.

Back in the punch card days of old.

Received on Fri Feb 21 2003 - 12:37:00 GMT

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