12 Sep
2016
12 Sep
'16
1:40 p.m.
On Sep 12, 2016, at 2:21 AM, Peter Corlett <abuse at cabal.org.uk> wrote:
On Sun, Sep 11, 2016 at 06:43:32PM -0700, Chris Hanson wrote:
No, the 68000 was a 32-bit CPU, as defined by the register width and programming model.
The fact that it was implemented with a 16-bit ALU and had a 16-bit data path to memory is
immaterial.
-- Chris
This person was talking about 680x0-based Macs
being ?16-bit.? Ugh.
The original 68000 *was*. Although there were instructions for 32 bit ALU
operations, it only had a 16 bit ALU and the operands had to go through the ALU
twice. This illusion went away with multiplication and division, which only
existed in 16 bit form.
The 68020 onwards made the CPU fully 32 bit, although various bits of legacy 16
bit cruft remained for compatibility.