The history of the PC processor is interesting and full of fierce
competition and advanced technology, yet short in the terms of years.
The modern history of PC CPU processors should have begun with a 5 MHz
8086 processor. Today we are routinely seeing CPU speeds in GHz. 20-some
years made a huge difference in PC processor development .
It was 8086 that started Modern PC Processor History.
CPUs have gone through many changes through the few years since Intel
came out with the first one. IBM chose Intel’s 8088 processor for the
brains of the first PC. This choice by IBM is what made Intel the
perceived leader of the CPU market. Intel remains the perceived leader
of PC processor development. While newer contenders have developed their
own technologies for their own processors, Intel continues to remain
more than a viable source of new technology in this market, with the
ever-growing AMD nipping at their heels.
The first four generations of Intel processor took on the 8 as the
series name, which is why the technical types refer to this family of
chips as the 8088, 8086, and 80186. This goes right on up to the 80486,
or simply the 486. The following chips are considered the dinosaurs of
the computer world. PC’s based on these processors are the kind that
usually sit around in the garage or warehouse collecting dust. They are
not of much use anymore, but many computer geeks don’t like throwing
them out because they still work.
Intel 8086 – 1978
This PC processor was skipped over for the original PC, but was used in
a few later computers that didn’t amount to much. It was a true 16-bit
processor and talked with its cards via a 16 wire data connection. The
processor contained 29,000 transistors and 20 address lines that gave it
the ability to talk with up to 1 MB of system RAM. Actually, the
designers at the time never suspected anyone would ever need more than 1
MB of memory. The PC processor was available in 5, 6,, 8, and 10 MHz
Intel 8088 - 1979
The 8088 is identical to the 8086 for practical purposes. The only
difference is that 8088 PC processor handles address lines differently
than the 8086 chip. This PC processor was the one that was chosen for
the first IBM PC, and like the 8086, it is able to work with the 8087
math coprocessor chip.
NEC V20 and V30 - 1981
These PC processors are considered as clones of the 8088 and 8086, but
they were claimed to be 30% faster than the Intel processors.
Intel 80186 - 1980
The 186 was a popular PC processor. Many versions had been developed in
its history. Buyers could choose from CHMOS or HMOS, 8-bit or 16-bit
versions, depending on what they needed. A CHMOS processor could run at
twice the clock speed and at one fourth the power of the HMOS chip. In
1990, Intel came out with the Enhanced 186 family. They all shared a
common core design. They had a 1-micron core design and ran at about
25MHz at 3 volts. The 80186 PC processor contained a high level of
integration, with the system controller, interrupt controller, DMA
controller and timing circuitry right on the CPU. Despite this, the 186
processor never found itself in a personal computer.
Intel 80286 - 1982
This 16-bit, 134,000 transistor PC processor was capable of addressing
up to 16 MB of RAM. In addition to the increased physical memory
support, this processor was able to work with virtual memory, thereby
allowing much for expandability. The 286 was the first “real” PC
processor. It introduced the concept of protected mode, an ability to
multitask or having different programs run separately but at the same
time. This ability was not taken advantage of by DOS, but future
Operating Systems such as Windows could play with this new feature.
There was some drawbacks of this ability. While this PC processor could
switch from real mode to protected mode, it could not switch back to
real mode without a warm reboot. This version of processors was used by
IBM in its Advanced Technology PC/AT and was used in many
IBM-compatibles. The processor ran at 8, 10, and 12.5 MHz, but later
editions of the chip ran as high as 20 MHz. While these PC processor
chips are considered paperweights today, they were rather revolutionary
for the time period.
Intel 386 - 1985 to 1990
The 386 pc processor signified a major increase in technology from
Intel. The 386 was a 32-bit processor, meaning its data throughput was
immediately twice that of the 286. Containing 275,000 transistors, the
80386DX PC processor came in 16, 20, 25, and 33 MHz versions. The 32-bit
address bus allowed the chip to work with a full 4 GB of RAM and a
staggering 64 TB of virtual memory. In addition, the 386 processors were
the first chips to use instruction pipelining, which allows the
processor to start working on the next instruction before the previous
one is complete. While the processor could run in both real and
protected mode, it could also run in virtual real mode, allowing several
real mode sessions to be run at a time. A multi-tasking operating system
such as Windows was necessary to do this, though. In 1988, Intel
released the 386SX, which was basically a low-fat version of the 386.
This version of PC processor used the 16-bit data bus rather than the
32-bit, and it was slower, but it thus used less power and thus enabled
Intel to promote the chip into desktops and even portables. In 1990,
Intel released the 80386SL, which was basically an 855,00 transistor
version of the 386SX processor, with ISA compatibility and power
management circuitry. 386 chips were designed to be user friendly. All
processors in the family were pin-for-pin compatible and they were
binary compatible with the previous 186 chips, meaning that users didn’t
have to get new software to use it. In addition, the 386 processors
offered power friendly features such as low voltage requirements and
System Management Mode, or SMM, which could power down various
components to save power. Overall, this chip was a big step for chip
development. It set the standard that many later chips would follow. It
offered a simple design which developers could easily design for.