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Here ya go John, text straight outta my old A+ Training Book:
On June 6, 1978, Intel introduced its first 16-bit microprocessor, known as the 8086. It had 29,000 transistors, 16-bit registers, a 16-bit external data bus, and a 20-bit address bus to allow it to access 1 MB of memory. When IBM entered the computer business, the 8086 was too powerful (and expensive) to meet its requirements.
Intel then released the 8088 processor, which was identical to the 8086 except for an 8-bit external data bus, and a slower top clock rate. This meant that 8-bit components (more common at the time) could be used for the construction of PCs, and 8-bit applications written for earlier machines could be converted for PC use.
In February, 1982, Intel introduced the 80286 6-MHz microprocessor (later pushing the clock speeds to 10 and 12.5 MHz), commonly called the 286, with a 24-bit address path. In 1983, IBM unveiled its PC AT (Advanced Technology) computer, based on the 286. It had a larger, boxier design, came with a standard hard drive, and a new expansion slot format, rendering older add-on cards obsolete.
The AT could run the same applications as the PC XT (8088), but run them faster. The use of a 24-bit address path allowed the 286 to access up to 16 MB of memory. The clone-makers soon followed suit, taking advantage of third-party versions of the 286. Chip makers Harris and AMD produced versions of the 286 that could run at up to 20 MHz.
Computers based on the 80286 chip featured:
Two memory modes (real and protected).
16 MB of addressable memory.
Clock speeds up to 20 MHz.
Reduced command set (fewer program commands to do more work).
Multitasking abilities.
Virtual memory support.
On June 16, 1985, Intel introduced the original 80386 (commonly known as the 386). This true 32-bit processor was equipped with a 32-bit external data bus, 32-bit registers, and a 32-bit address bus. The first models shipped with a clock speed of 16 MHz, and the CPU sported 275,000 transistors. It could directly address 4 GB of RAM, and 64 TB (terabytes—a terabyte is approximately one trillion bytes) of virtual memory. According to Intel, the 386 could hold an eight-page history of every person on earth in that address space. The 386 was a true generational leap in PC computing, with true multitasking capability—it really could run more than one program at a time. That was due to a third memory mode, called virtual real mode, that allowed independent MS-DOS sessions (called "virtual machines") to coexist on the same system at once. It spawned a host of programs called "memory managers" designed to optimize (and troubleshoot) the more complex world of virtual memory.
The original 80386 chips shipped with speeds of 12 or 16 MHz. Intel produced faster versions—25 and 33 MHz, while AMD manufactured a 40-MHz variant. The 386 provided both the real and protected mode available in the 286.
By April of 1989, the 386 was running at clock speeds of 33 MHz, and Intel was calling it the 80386DX to distinguish it from a lower-cost model, the 386SX.
April 10, 1989, brought us the 80486 line of processors. Once again, the rallying cry was "better and faster." By this time, applications like CorelDRAW, Adobe PhotoShop, and desktop-publishing tools like PageMaker and Ventura Publisher were generating more interest in faster systems. Microsoft Windows was gaining popularity and on its way to becoming the standard desktop environment.
The 486 processor started life at 25 MHz and could address 4 GB of RAM and 64 TB of virtual memory. It is the first PC CPU to break the 1-million transistor mark with 1,200,000. It provided a built-in math coprocessor (older PC CPUs offered separate math coprocessors as an option—usually with a similar number ending in a 7 rather than a 6). The combination speeded up graphics programs that used floating-point math.
By 1993, Windows was standard, and users expected a lot more from PCs in performance and features. Increasing software sophistication led to increasing memory usage and hard disk drive requirements. The market was ready for a major upgrade in CPUs, and Intel once again addressed that need. The new Pentium processor signaled a radical redesign of both the CPU and naming conventions.
With their CPUs identified by numbers, Intel faced a business problem: numbers cannot be trademarked. The company's strategy was to substitute a trademarkable name, "Pentium" for their upcoming chips that would otherwise have been named "586." The word is based on the Latin word for the number five, and this chip would have been the 80586. The original design has been revamped several times since 1993, and now there are Pentium IIs and IIIs. Like the older PC CPUs, the Pentium has spawned its share of clones, leading to entry-level PCs priced under $400.
The Pentium (Series I) offers the following features:
Speeds of 60 to over 200 MHz.
32-bit address bus and 32-bit registers.
64-bit data path to improve the speed of data transfers.
Dual pipeline, 32-bit data bus that allows the chip to process two separate lines of code simultaneously.
At least 8-KB write-back cache for data and an 8-KB write-through cache for programs. (Types of caches are explained in more detail in Chapter 7, "Memory.")
"Branch prediction"—in which the program cache attempts to anticipate branching within the code. The CPU stores a few lines of code from each branch so that when the program reaches the branch, the Pentium already has the code stored within the cache.
And such is history. The first Intel chips were the 4004, but they gave rise to the 8086 and 8088. The 8086 was the first "x86" chip. Followed by the 80286, 80386, 80486, 80586(Pentium) and so on. "X" is just a variable representing the the first 3 characters of the model. They're all "86s".
Indeed there is a little to learn in the show each and every morning. :D
Cliff
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:D just a thought hehe
