Friday, February 03, 2012

Moore's Law and the ever-shrinking computer

A friend sent me this 1956 photo with the heading "Guess What This Is?"  I recognized it immediately as some kind of data storage for an early computer.

It's the hard drive for IBM's model 305 RAMAC computer.  It weighed around 1 tonne and stored 5 megabytes of data (equivalent to one JPEG photo from a modern camera).

About 25 years after that photo was taken, I was writing software in an early attempt to automate the complex task of starting up a paper machine. The chosen computer had a 24-bit processor and held 48 megabytes of data on huge interchangeable disk packs. The computer room looked like a kitchen: the computer was the size of a refrigerator, the disk drive the size of a dishwasher, and each disk pack resembled a very large cake cover. The price of the whole system would have bought two 3-bedroom townhouses.

The computer had only one programming language, a crippled version of FORTRAN that limited each  compiled program to 1500 bytes and did not allow subroutines. We got around that by using hundreds of programs that called each other as they terminated.

The budget was limited, so we had to perform tests to determine process conditions for which no sensor had been purchased. The tests took a long time, so in the end our automated approach was no faster that an experienced operator. Still, we managed to publish a paper about our experiences!

Around that time the movie "War Games" was released, about a teenager who accidentally comes close to starting World War III while hacking into what he thinks is a new computer game, but is actually NORAD's war strategy simulator. I show this exciting movie to my students to demonstrate the progress we've made in the past 30 years. 

The War Games sets are packed with early 1980s computer systems.  In one scene, the actors walk through NORAD's computer centre, a cavernous room filled with huge tape drives and computers.  I make my students count the items and estimate their approximate volume.  Then I have them apply Moore's Law to answer the multiple-choice question: "Today, all that computing capability would fit inside a...".  Six years ago, the correct choice of answer was "backpack."  Last year it was "smart phone"  By next year it will be "wristwatch."

Postscript, 2015-01-26: We recently found the "backup logbook" we kept for our home computer, starting in early 1994. We paid $342 for a tape drive and $102 for three tapes, and made backups faithfully once a week. After several years we switched to CD-RWs. Today we back up over our home network to a mirrored server. I'd like to think that our future systems won't have any moving parts, but we've seen a couple of solid-state drives fail badly, so we'll always need backups!

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