Hardware Reference
In-Depth Information
In the early 1980s, I had a system containing both a MOS Technologies 6502 and a Zilog
Z80. It was a 1MHz (yes, that's one megahertz!) 6502-based Apple ][+ system with a Mi-
crosoft Softcard (Z80 card) plugged into one of the slots. The Softcard contained a 2MHz
Z80 processor, which enabled me to run both Apple and CP/M software on the system.
AllthesepreviouschipssetthestageforthefirstPCprocessors.Intelintroducedthe8086
in June 1978. The 8086 chip brought with it the original x86 instruction set that is still
present in current x86-compatible chips such as the Core i Series and AMD Phenom II.
However, it was a reduced-feature version of the 8086, the Intel 8088, that became the
processor used by the first IBM PC.
To learn more about the 8086 and 8088, see “
P1 (086) Processors
,” later in this chapter.
PC Processor Evolution
SincethefirstPCcameoutin1981,PCprocessorevolutionhasconcentratedonfourmain
areas:
• Increasing the transistor count and density
• Increasing the clock cycling speeds
• Increasing the size of internal registers (bits)
• Increasing the number of cores in a single chip
Intel introduced the 286 chip in 1982. With 134,000 transistors, it provided about three
times the performance of other 16-bit processors of the time. Featuring on-chip memory
management, the 286 also offered software compatibility with its predecessors. This re-
volutionary chip was first used in IBM's benchmark PC-AT, the system upon which all
modern PCs are based.
In1985cametheIntel386processor.Withanew32-bitarchitectureand275,000transist-
ors, the chip could perform more than five million instructions per second (MIPS). Com-
paq's Deskpro 386 was the first PC based on the new microprocessor.
Next outofthe gate wasthe Intel 486processor in1989.The 486had1.2million transist-
ors and the first built-in math coprocessor. It was some 50 times faster than the original
4004, equaling the performance of some mainframe computers.
Then, in 1993, Intel introduced the first P5 family (586) processor, called the Pentium,
setting new performance standards with several times the performance of the previous
486 processor. The Pentium processor used 3.1 million transistors to perform up to 90
MIPS—now up to about 1,500 times the speed of the original 4004.
