Saturday, August 30, 2014

Old computer ad...

Old computer ad...  From 1952, the year I was born.  High resolution version here.  The computer is based on vacuum tubes and crystal diodes (an early version of semiconductor diodes).  The main memory was about 2kb, and the tape mass storage about 400kb – absurdly small by today's standards (and about one 30 millionth of my laptop!).  The clock speed was 120 kHz, about one 25,000th as fast as my laptop.

Some things that I noted as I read the ad:
  • It refers to “binary digits” – now called “bits”!
  • The main memory was based on a magnetic drum, as were some of the computers I learned on in the U.S. Navy.  These posed special challenges when programming, as the memory wasn't randomly accessible – the access time varied depending on how far the drum had to rotate to get to the word you wanted to read.
  • I love the way all the ALU capabilities are listed.  There's one listed that I never heard of: multiplication with “round-off.”  I'm guessing that means the 30 most significant bits are returned, rounded.
  • The main I/O is a Flexowriter, a device I'm very familiar with.  Several of the computers I used in the Navy had attached Flexowriters, and I was trained to maintain them (oil and bending metal were involved).  Later, in the late '70s, I bought a used one and connected it to my homebrew Z80 system.  I still remember the smell of them; as they warm up the Flexowriters gave off an aroma of lightweight oils, like hair clippers.
  • Uses 3 kilowatts of power – the same as 30 hundred watt light bulbs.  My laptop averages about 60 watts.  It's hard to directly compare the power efficiency of my laptop vs. the advertised computer, but the difference is on the order of several million to one.
  • Has front panel controls and indicators that allow single-step or single-cycle operation, examination and modification of register contents, etc.  This is exactly like the Navy computers I learned on, and it's a capability that I still miss :)

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