Microprocessor Progression Intel complete 8-bit computer on one chip
Microprocessor Progression: Intel
The Intel 8080 was the first microprocessor in a home computer. See
The first microprocessor to make it into a
home computer was the Intel 8080, a
complete 8-bit computer on one chip, introduced in 1974. The first
microprocessor to make a real splash in the market was the Intel 8088,
introduced in 1979 and incorporated into the IBM PC (which first appeared around
1982). If you are familiar with the PC market and its history, you know that the
PC market moved from the 8088 to the 80286 to the 80386 to the 80486 to the
Pentium to the Pentium II to the Pentium III to the Pentium 4. All of these
microprocessors are made by Intel and all of them are improvements on the basic
design of the 8088. The Pentium 4 can execute any piece of code that ran on the
original 8088, but it does it about 5,000 times faster!
The following table helps you to understand the differences between the
different processors that Intel has introduced over the years.
The date is the year that the processor was first
introduced. Many processors are re-introduced at higher clock speeds for many
years after the original release date.
Transistors is the number of transistors on the chip. You
can see that the number of transistors on a single chip has risen steadily over
Microns is the width, in microns, of the smallest wire on
the chip. For comparison, a human hair is 100 microns thick. As the feature size
on the chip goes down, the number of transistors rises.
Clock speed is the maximum rate that the chip can be
clocked at. Clock speed will make more sense in the next section.
Data Width is the width of the ALU. An 8-bit ALU can
add/subtract/multiply/etc. two 8-bit numbers, while a 32-bit ALU can manipulate
32-bit numbers. An 8-bit ALU would have to execute four instructions to add two
32-bit numbers, while a 32-bit ALU can do it in one instruction. In many cases,
the external data bus is the same width as the ALU, but not always. The 8088 had
a 16-bit ALU and an 8-bit bus, while the modern Pentiums fetch data 64 bits at a
time for their 32-bit ALUs.
MIPS stands for “millions of instructions per second” and
is a rough measure of the performance of a CPU. Modern CPUs can do so many
different things that MIPS ratings lose a lot of their meaning, but you can get
a general sense of the relative power of the CPUs from this column.
From this table you can see that, in general, there is a relationship between
clock speed and MIPS. The maximum clock speed is a function of the manufacturing
process and delays within the chip. There is also a relationship between the
number of transistors and MIPS. For example, the 8088 clocked at 5 MHz but only
executed at 0.33 MIPS (about one instruction per 15 clock cycles). Modern
processors can often execute at a rate of two instructions per clock cycle. That
improvement is directly related to the number of transistors on the chip and
will make more sense in the next section
Entry filed under: Motherboards.