Mailinglist Archive: opensuse (4020 mails)

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Re: [SLE] new v9.2 is out-terminal question
  • From: James Knott <james.knott@xxxxxxxxxx>
  • Date: Tue, 26 Oct 2004 10:54:13 -0400
  • Message-id: <417E6515.80008@xxxxxxxxxx>
Richard wrote:
On Monday 25 October 2004 05:32 pm, Bruce Marshall wrote:

My first computer experience was with a IBM 650. The memory was on a
rotating belt-driven drum. Sometimes with a power spike, the belt
would snap..... :-)

Didja ever see what happens to a 6 foot drum with fixed heads when there is a sudden phase reversal? The drum, rotating at 3600 rpm, stops in a fraction of a rotation as it slams into the heads.
I doubt if many here have ever heard of, much less worked on a serial drum machine using ac logic. That was the first Process Control Computer, a RW/BR-300 invented around 1957 and still controlling the original process at the Texaco refinery when I left the company in 1973. You had to speak machine language on that one, assembly came later.

I used to work on a system that used a memory drum. It was from a company called "Teleregister". It was built with vacuum tubes and relays, and was installed in the old Toronto Stock Exchange a year before I was born. On this drum, the heads were fixed in position (we used to use a piece of paper as a feeler gauge, to adjust the head gap), so there was no danger of a crash. This "computer" had hard wired programming. If you want to make a change, you had to program it, using wire cutters and soldering iron! Another system I occasionally worked on years later (Phillips DS-714) had a drum, with an interesting feature. The drum was slightly tapered and when powered up, would gradually rise, as it's speed increased, until it was close enough to the heads. If the power died, the drum would slowly drop, as it slowed, protecting the heads from a crash.

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