Re: problem using FILE pointer

On Fri, 13 Feb 2009 11:04:58 +0100, David Brown
<david@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

The 68K support is a different story. The 68K family has always been
32-bit, not 16-bit. It has some 16-bit features - a 16-bit external
databus, and the original 68000 used a 16-bit wide ALU (running twice
for 32-bit operands). But these are minor implementation details,
trading speed against cost and chip size. The instruction set
architecture and basic register width are what counts - it was 32-bit
from its conception.

IMO the ALU width defines the chip, but I won't debate that here.


The first target for the first version of gcc was the 68k, and the 68k
family (now as ColdFires) is still a major target that is actively
developed and improved. Most of the improvements are through generic
gcc changes or ColdFire-specific changes, but they still affect
compilation for the 68k.

Coldfire is only partly 68K compatible - it has the same instruction
set, but not all instructions are implemented - in particular there
are fewer addressing modes - so there is a major impact on
compilation. Coldfires are more memory bound than real 68Ks and
require higher clock speeds and bigger caches to get equivalent
performance where the 68K could use more complex addressing modes.
And v4,v5 Coldfires have an incompatible FPU so you'll get different
answers than you would if you run the code on an 040,060 or on an
earlier chip with 68881,2 coprocessor.

George
.

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