Re: why bookworm isn't called deb12?

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Motorola's 68000 line had an internal 32 bit architecture, which made
> the CPU both performant and expensive.

Hmm... it had a (non-internal) 32bit instruction set architecture
(i.e. programmers could directly manipulate 32bit entities), but
internally it manipulated only 16bit at a time (e.g. a 32bit addition was
performed by using twice the 16bit adder).  The external bus sent and
received 16bit as well.

> But a manufacturer of systems could contain the overall cost by using
> 8-bit devices outside of the CPU.

Indeed, for this reason the 16bit bus of the 68000 had some details that
made it easier to interface with 8bit peripherals.

But it still made the cost of the overall system higher than a 68008
since it needed 16bit memory, i.e. twice as many memory chips.

> The first generation was hybrid 16/32 bit internally, and came in
> variants selected for cost vs performance: 8, 16 or 32 bit external bus.

I've never heard of a version of the 68000 with a 32bit external bus.

AFAIK the first CPU with  32bit external bus in the 68k family was the
68020, which was a completely new design released several years later,
not just a "variant".


        Stefan