Meaning of "architecture width" - Re: 68K Macs with MacOS 7.5 still in production use...

Jecel Assumpcao Jr. jecel at
Fri Sep 16 17:20:45 CDT 2016

I wrote:
> The 68000 has three separate 16 bit ALUs: one for DataLow, one for
> AddressLow and another for AdressHigh. DataHigh can be processed by
> either the first or the second one. The first one implements all
> operations while the other two only do add/subtract and some limited
> shifting.
> See figure 8 of:

Ooops- my explanation got the last two ALUs backwards. DataHigh and
AddressHigh share an ALU.

Note that in the conclusion to this 1979 article, the Motorola engineers
say "It is a 32-bit architecture that supports many data types and data

- Jecel.

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