Computing history (was Synthfool)

[KA4HJH]

>And for code hackers, check out Woz's IWM - Incredible Woz Machine for the
>Apple ][ - official name Sweet16 an incredible piece of code - he
>essentially created a virtual 16-bit CPU with floating point math that could
>run on the 6502 with very little overhead and you could switch in and out of
>it when needed, pass stuff back and forth to it...  Amazing stuff.  Terse.
>Fast.

There wasn't room for it in the ][+ so they left it out. Never got to play
with it.

>My read on this is that they decided to go with the absolute fastest CPU
>they could find and make it do EVERYTHING.  They were trying to make the
>thing as cheap to manufacture as possible so they didn't use fancy keyboard
>controllers, disk controllers, video controllers, etc...  They used the bare
>minimum of glue logic and had the poor 68000 run the entire show.  Elegant
>design and low body count but you can paint yourself into a corner and make
>it really hard to upgrade.

This is the Wozniak method. Only Woz didn't have a lot to do with it by
this point. The advantage is flexibility, and in some cases suitable
dedicated devices don't exist--not yet, anyway. The down side is that it
overloads the processor. The trick is to find a happy medium, which takes a
while.

They progressively put more of the floppy stuff off onto a chip, which was
basically a hardware subset of Woz's DOS code, combining his group coding
scheme with CLV. That's why Apple got 800k out of a disk and MS-DOS only
got 720k. I vaguely remember it being called the SWM chip for "Super Woz
Machine" or something like that. What a crazy bunch.

BTW, despite what was claimed in Byte magazine, the Lisa's CLV 5.25's were
crap. Apple ended up settling a lawsuit out of court over it because it was
so unreliable. Oops. They got out of the floppy drive business after that.

Terry Bowman, KA4HJH
"The Mac Doctor"