🚀 go-pugleaf

In <jgkDFG9HJ.49x@netcom.com> Joe Keane <jgk@netcom.com> writes:

>Then look at the Alpha instruction set.  It has instructions for 32-bit add,
>subtract, and multiply.  It also has instructions for 32-bit load and store,
>even though it *doesn't* have single instructions for byte load and store!
>That seems just a bit peculiar for a `pure' 64-bit, byte-addressed machine.

Then look at the PDP-11 instruction set.  It supports both byte and
word operands.  That seems just a bit peculiar for a `pure' 16-bit,
byte-addressed machine.

>If it seems a bit ambiguous at the assembly level, look at the C interface.
>For integer types, `int' is usually the `natural word size' of the machine,

Hear, hear.  How many C compilers for the 8080 or Z80 using an 8-bit int
have you seen/used?

>and it's common that `short' is a half-word, and/or `long' is a double-word.

As far as I know, the concept of "word" is meaningless on Alpha.  "half-word"
and "double-word" even more so.  The C compilers for Alpha simply assign a
_standard_ type to every integer size supported by the implementation.
This is precisely what the C compilers for other platforms should have done,
as well, instead of stupidly assigning int and long to the same size
and inventing the gratuitous long long type for 64-bit integers.

>If you look at the Alpha, this scheme fits perfectly: it's a 32-bit machine.

Except that it happens to have 64-bit general purpose registers and
supports a 64-bit virtual address space (and much more than 4 GB of real
memory), features which don't fit at all to a 32-bit machine (at least,
not to any that I know of).

Dan
--
Dan Pop
CERN, CN Division
Email: Dan.Pop@mail.cern.ch 
Mail:  CERN - PPE, Bat. 31 R-004, CH-1211 Geneve 23, Switzerland