(We used to drink coffee slower back then).
Next some bright spark invented EEPROMs (with the E standing for electrically) so you could ask the chip to erase your dodgy old code before asking it to burn your new dodgy code into itself.
Around this time a lot of these chips were still removable so when you inadvertently erased the part you could always go get another one and replace it with only some minor pin bending.
Some even brighter sparks decided that it'd be fun to make the EEPROM parts surface mount so now when a virus kills your code, or you inadvertently kill it yourself trying to update the splashscreen with pics of { Paris Hilton, Ray Beckerman, Bruce Schneier, Chuck Norris }, you now have to whip out your soldering iron and take a deep breath.
In the same way that a lot of flash storage has a little 'lock' switch there were link settings on some motherboards which you could set to make sure the chip wouldn't modify itself or erase itself (although the chips didn't always properly support this).
Similarly various microcontroller parts have a fuse bit you can blow to disable any future updates. There were also all sorts of weird and wonderful schemes such as having a couple of copies of the BIOS so the spare could replace the 'broken' copy.
It seems a shame this hasn't become industry standard (or if it has its passed me by in my state of decrepulousness and please accept my apologies...)
Alex/
Truly simple systems... require infinite testing. -- Norman Augustine