Teaching kids about computers...

On Sunday 25 November 2007 19:26, Ensor wrote: For one version of it, yeah. There were at least four different versions of the boards out there, I'd have to check the manual to be absolutely sure of the count. And there were some significant differences in some areas, as well as some production changes. One thing I saw from time to time was some diodes added to either the serial bus or the user port to protect chips, but *never* to the joystick ports, where they were most needed -- the design of that silly thing was such that you'd tend to hit the pins on those joystick connectors while reaching for the power switch, and we replaced a lot of 6526 chips for that reason. A fix for that was to jam a very thin slice of black foam into the connectors, which was fine for joysticks, though some other peripherals got upset by this and you'd have to take it out to make it work properly. One area where the boards differed very much was in the video section. Earlier units used several TTL parts for the clocks, later ones went to a gate array. Another was RAM, the later boards used two 64Kx4 parts instead of eight 64Kx1, and the very latest ones I saw combined two of the ROMs (Kernel and BASIC?) into one single chip. Not that any of this mattered much from the programming perspective, I guess. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin