Questions tagged [x86]

In computing, x86 is the generic name given to the family (architecture) processors based on Intel 8086 by Intel Corporation.

The architecture is called x86 processors because the first of this family were identified only by numbers ending with the string "86": the 8086, the 80186, the 80286, the 80386 and 80486. As you can not have a trademark on numbers, Intel and most of its competitors began to use names that could be registered as trademarks as to the Pentium processor generations later, but the old nomenclature had forged a term for all family.

In other words, we can say that the x86 term refers to a family of the instruction set architecture, based on the Intel 8086. The 8086 was launched in 1978 as an extension of 16-bit Intel was one of eight first who introduced the microprocessor-based segmentation to overcome the 16-bit addressing barrier of the previous chips. The x86 term derived from the fact that the successors to the 8086 also had names ending in "86". Many additions and extensions were added to the x86 instruction set over the years, often with full backward compatibility. The architecture was implemented in processors from Intel, Cyrix, AMD, VIA, and many others.

144 questions
67
votes
8 answers

Did Windows ever support any hardware architectures other than x86?

Microsoft Windows Internals, 4th Edition says: The architecture of the Intel x86 processor defines four privilege levels, or rings, to protect system code and data from being overwritten either inadvertently or maliciously by code of lesser …
xiaokaoy
  • 822
45
votes
4 answers

Can a 64-bit computer (x86) run a 16-bit OS natively, without emulation?

If you were to build a modern x86 computer with completely modern parts, could you load MS-DOS 6.11 and Windows 3.11 onto it without any emulation or even with FreeDOS? I recently saw a video of it being done with Windows 95, a 32-bit OS, but can it…
ioi-xd
  • 543
29
votes
5 answers

How to check if a binary requires SSE4 or AVX on Linux

On Linux,/proc/cpuinfoallows one to check all the CPU flags the machine has in a simple way. Usually, if a program requires a superset of a machine's instruction set, the easiest way to determine this is to run it and see whether it raises…
user2284570
  • 2,020
21
votes
3 answers

Latency of CPU instructions on x86 and x64 processors

I'm looking for some table or something similar that could help me to calculate efficiency of assembly code. As I know bit shifting takes 1 CPU clock, but I really looking how much takes addition (subtraction should take the same), multiplication…
ST3
  • 785
15
votes
5 answers

Why did Intel drop the Itanium?

I was reading up on the history of the computer and I came along the IA-64 (Itanium) processors. They sounded really interesting and I was confused as to why Intel would decide to drop them. The ability to choose explicitly what 2 instructions you…
11
votes
7 answers

Why does Windows 7 x64 work faster than an x86 edition on my PC?

Why does Windows 7 x64 work faster than an x86 edition on my PC even though I mostly use x86 things in it? What's wrong with me, and what am I missing? Majority of the things I use is x86 (e.g. DAWs, games, media players). A considerable amount of…
Jasper
  • 441
10
votes
2 answers

Why do VirtualBox guest kernels run in ring 1 instead of ring 3?

When VirtualBox runs on an x86 platform, according to the documentation: When hardware virtualization (i.e. VT-x or AMD-V) is enabled , the hypervisor (i.e. VirtualBox itself) runs in VMX root mode (aka ring -1), and virtual machines run in VMX…
catanman
  • 331
10
votes
1 answer

X86 Address Space Controller?

I understand that on x86, certain ranges of physical memory addresses are mapped to the BIOS, others to RAM and yet others to I/O devices. I would like to know which hardware component is responsible for this mapping/translation. My guess is the…
9
votes
1 answer

Is it possible for an x86 processor to match an ARM processor in terms of performance per watt?

From my personal experience with my tablet, and from the benchmarks and articles I've read, it always seems ARM processors, as seen in virtually all mobile devices, deliver incredible performance for the amount of power they consume. It really…
bwDraco
  • 46,683
9
votes
4 answers

How does OS X run 64-bit Binaries while running on a 32-bit Kernel?

I have recently figured out that Mac OS X actually CAN run 64-bit (x64) applications even if x86 kernel is loaded. That was shocking for me for a first time. But then I've realized that it is really weird if system is up and running under x64…
pechenie
  • 193
8
votes
1 answer

Confusion about software for x86, x86_64 and x64

do softwares meant for x86, install on x86_64 and x64. I am focusing on linux. What problems can occur. I have never been comfortable with the differences. Could you explain?
Rohit Banga
  • 2,494
8
votes
2 answers

Can Intel microcode updates be rolled back?

Let's say I apply (or have applied for me by an automatic update process) a microcode update which fixes, for example, a hyperthreading bug on my Skylake chip. Are such updates irreversible, or can I later switch back to an earlier microcode?
BeeOnRope
  • 1,078
8
votes
4 answers

Performance-impact of Hyper-Threading

I just read an article on Heise Online (look at the table, the rest is German) which claimed, that Hyper-Threading slows down single-threaded programs although they don't use the second thread of a core. I.e. if you disable HT in the BIOS, the…
7
votes
3 answers

Google Android OS on x86?

How can I install Google's Android OS on an x86 platform? Are there any prerequisites for doing this?
Jony
  • 385
  • 1
  • 3
  • 10
7
votes
1 answer

Can VirtualBox run operating systems designed for ARM processors?

For example, can I run Android, which is mostly run on ARM processors, run on VirtualBox on x86 Intel processors? I am aware of Android x86, however, that is not a viable solution.
1
2 3
9 10