Processors.


This is going to be a tutorial that will (hopefully) teach you something about some of the more popular processors in computers.

This is the first part of it. This one covers Intels beginings and goes up to the 486, When i get a little more time ill finish where i left off at which is where the pentium begins) And then i will start on other brands and companies that made processors. (well if i get a good responce i will, if no one likes it ill stop though.)




Intel:


The Most popular CPUs in use today are designed by Intel, and typically found in IBM based PCs. The first processor by Intel was the 8088, the CPU found in the original IBM PC.

It originally had an internal and external CPU click speed of 4.7 MHz, and there was no L1 or L2 cache. Cache memory wasn’t needed because the memory ran at the exact same speed as the internal and external CPU clock.

The address bus on the CPU was 20 bits wide, a number chosen to enable the computer to address 1,048,576 bytes of memory, or 1MB. Not very much huh?
But think about it like this, back then you didn’t need much RAM anyway, almost everything was character based.
But even this was 16 times the usual 65,536 bytes or 64K which was common in those days.

Most engineers thought this was more than a computer would ever need. The address BUS was 8 bits wide, but internal operations could be performed at either 8 or 16 bit logic. The 8 bit data bus made it cheap and easy to build computers around the chip.

The 8088 was followed by the 8086, which was the first Intel processor to have a 16 bit data path. Besides that it was identical to the 8088. Later on, clock speeds soared to a whopping 20 MHz. Intel has built on this CPU ever since, following it up with other processors that became popular in PC computers.

The 80286 was the beginning of the 80x86 line, featuring more advanced chip functionality to provide more commands to the end user (Back when end users knew what a command was.) and higher clock speeds of 8, 16, and even 20 MHz.
This chip also ran at identical internal and external clock speeds, and had no L1 and L2 cache.

The 80386 introduced a 32-bit address and data bus, and still higher clock speeds of 16, 20, and even a turbo like 40 MHz.
This chip was the first in the Intel 80x86 chip family that could perform operations using 32 bits of data at a time.

Because the chips were so fast, running at speeds over 16 MHz, they were the first Intel chips in this line to support external, or L2, cache.

The external and internal clocks on the chip were still the same but new instructions were introduced.
Like the 8088 and 8086 combination, this chip also came in two data port versions. The 80386 was officially called the 80386DX and had a 32 bit data path.

For “Hey we want to make money” reasons they also made a chip that had a slight problem in it, but they called it a feature and marketed it as the 80386SX, which had a 16 bit external data path and 24 bit address bus width.

The next chips released were the 80486 family, the first line of chips in which Intel used different internal and external clocks.
This chip is the first one to have L1 cache on the chip, which runs at the internal CPU speed, as well as features for external L2 cache, which runs at the speed of the external clock.

Unique in the 80486 line was the inclusion of hardware dedicated to performing mathematical operations. Some 486 models, the initial ones known as DX chips, ran at the same internal and external clock speed.

Newer models identified as DX2 or DX4 chips, ran internally at two or four times the external clock. This is the last series of chips Intel made that had a “little brother” with a reduced data path, referred to as the 80 486SX.