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August 12, 2008
Core memory
Core Memory is a nice collection of photos by Mark Richards. I believe they come from his book Core Memory: A Visual Survey of Vintage Computers.
When I first got into this business in 1981, one of the machines I worked with was a Modcomp Classic. It came new with 512 KB of RAM (twice the RAM of the previous model) and a fast 16-bit CPU that was four RCA 4-bit processors in parallel. It had a front panel somewhat similar to the one above. (I could tell you about the old discrete-component, drum memory GE computer the Modcomp replaced but I don't want to tax your patience too much.)
To start one of these machines, you entered a simple program (a dozen instructions, say) into memory using the toggle switches on the front panel. Then you started that program running.
The program you toggled in would read the bootstrap loader, stored in ROM, into memory and start that. In turn, the loader would go looking for a boot device - a tape, a hard disk or even a card reader - and load the operating system into memory. As you can guess, this was a fairly slow process. A boot from disk that went quickly probably took about 5 minutes. If you used a tape drive (or a card reader) it took even longer.
We kept the boot instruction sequence written in machine language (hexadecimal) on the backs of punch cards on the inside of the cabinet doors. Those were the days, my friend.
Posted by joke du jour at August 12, 2008 06:52 PM
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