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32-bit and 64-bit ALU architectures are available.
A 64-bit architecture, by definition, has 64-bit integer registers.
Many computers have had 64-bit IEEE floating point for many years.
The 64-bit machines have been around for a while as the Alpha and
PowerPC yet have become popular for the desktop with the Intel and
AMD 64-bit machines.
Software has been dragging well behind computer architecture.
The chaos started in 1979 with the following "choices."
The full whitepaper www.unix.org/whitepapers/64bit.html
My desire is to have the compiler, linker and operating system be ILP64.
All my code would work fine. I make no assumptions about word length.
I use sizeof(int) sizeof(size_t) etc. when absolutely needed.
On my 8GB computer I use a single array of over 4GB thus the subscripts
must be 64-bit. The only option, I know of, for gcc is -m64 and that
just gives LP64. Yuk! I have to change my source code and use "long"
everywhere in place of "int". If you get the idea that I am angry with
the compiler vendors, you are correct!
The early 64-bit computers were:
DEC Alpha
DEC Alpha
IBM PowerPC
Some history of 64-bit computers:
Java for 64-bit, source compatible
Don't panic, you do not need to understand everything about
the Intel Itanium architecture:
IA-64 Itanium
Some history of the evolution of Intel computers:
Intel X86 development
long list
now quantum
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