Processor family developed by IntelCorporation
, and now made by Intel and numerous competitors, which has historically powered the PeeCee
) line of computers for the 20+ years that it has existed. Usually referred to as the x86
architecture, in reference to the original (pre-Pentium) numbering scheme. Also called the "IA-32" (Intel Architecture 32-bit) line; for the 32-bit members of the family (not including the 80286 and older; nor including the 64-bit versions).
The processor family consists of LittleEndian
processors, with register widths ranging from 16 to 64 bits. Originally a ComplexInstructionSetComputer
architecture; modern variants are ReducedInstructionSetComputer
devices with an external system which translates the CISC-ish instruction set into a RISC core. Notoriously register-poor (only 8 general purpose registers). Often criticized for being a kludgy architecture (it carries 'round 20 years worth of backwards-compatibility baggage, plus source-level up-compatibility with the original 8-bit 8080), and for the immense amount of power consumed and heat generated.
Notable members of the line has included:
- The 8086 and 8088. Hybrid 8/16 processors used in the original PCs. Limited to 1Mb of directly-addressable memory (further reduced to 640k by the PC architecture, which put the video frame buffer at address 0xA0000). The 8088 only had 8 external address lines, so 16-bit transfers required an additional bus cycle. Well-known for it's widely-despised segmented memory model. Originally ran at 4.077MHz; was later available in 8Mhz and 10Mhz. The 10Mhz was often slower; given that it was faster than the memory devices at the time (and thus required wait states). Caches were not yet found in PCs.
- The 80186 (or just 186). Not used in PCs (except for the Mindset), found in some embedded systems and Amiga bridge boards.
This is not true. I owned one of these in the early 90s (i technically still do even if i doubt i would be able to locate all the parts). I think it was called Monroe System 2000 and ran "Monroe DOS 2.0" (which was pretty much identical to MS/PC-DOS 2.0 but impossible to upgrade to anything 3.x).
- 80286. Added a rudimentary MMU, and the ability to address >1Mb of memory. Available in speeds up to 25MHz or so.
- 80386 family. The first fully 32-bit member of the line. Supported faster clock speeds, as well as a much more powerful MMU (which hasn't changed all that much since). Capable of running a protected OS with a flat address space; several soon appeared at around this time (WindowsNt, IbmOsTwo, early versions of LinuxOs, XenixOs?). AmericanMicroDevices? entered the market at this point; with a line of competing (and compatible) processors also referred to as the 386. Intel, of course, sued. Available in speeds up to 80MHz.
- 80386DX. With an external 32-bit data bus.
- 80386SX. With an external 16-bit data bus.
- 80486 family.. The first pipelined version of the family (still single-issue though), capable of a throughput of nearly one instruction per clock cycle. Added a floating point coprocessor on-chip (all earlier versions required an off-board FPU, many PCs didn't have one installed). Available in speeds from 33Mhz up to 133 Mhz. Quite a few members of this family:
- 80486SX. Without the floating point coprocessor.
- 80486DX. With the coprocessor
- 80486DX2, DX4. Like the DX, but with a ratio of 2 (or 4) between the CPU and memory subsystems; allowing for faster CPU speeds than the memory devices at the time could support.
Around this time, Intel lost its trademark infringement suit with AMD, on the grounds that numbers could not be trademarked. So rather than calling the next major change in the family the 80586; it was rechristened the Pentium (a name Intel could trademark). Subsequent versions have been Pentium-n
for some n
; Intel has yet to release a Hexium or a Heptium (and likely never will).
I'll let someone fill in the history of Pentium's; my knowledge of ancient history is more solid than my knowledge of recent history.
- Pentium Pro
- Pentium with MMX (MultiMediaExtensions?)
- Pentium 2
- Pentium 3
- Pentium 4
- Xeon versions
- Pentium M
- Pentium D
In 2005, AppleComputer
announced that the AppleMacintosh
line of computers would migrate from the PowerPc
architecture to the ExEightySix