How Computers Boot Up

Monday, April 11, 2011

I came across two excellent articles recently and am posting a short commentary on them here and at Motherboard Chipsets and the Memory Map .

The first article should be of general interest to anyone who sits waiting for the computer to re-boot, or anyone who hates the process so much that they avoid a re-boot as much as possible.

This stuff is of interest to me in part because the first computers I ever used, in 1967, were bootstrapped – you pressed a button on the card-reader which caused the machine to read the first punched-card in a deck of 80-column cards, which card contained enough instructions to read the next card, and so on, until the whole program was loaded and ready to process data.

You’ll read this in “Things start rolling when you press the power button on the compute”, under the heading Boot Sequence, Boot being an abbreviation for Bootstrap, and nothing at all to do with giving the computer a kick.

In 1973-74 I was enrolled in a Systems course, part of which was to design computers from the DEC handbook – working out how to combine NAND, NOR and NOT gates into half-adder circuits and then continue upwards, and as a pastime I wrote a compiler for a computer with only one instruction .

Anyway, give the Duartes paper a single read-through; don’t be thwarted by some of the stuff you don’t understand; just skim through it and then say “Whew! I never realized how complex a device these things are”.

Much more complex than a vacuum-cleaner, even though it too has an on-off switch.

Talk to Me !

Search