The evelution of the microprossesor

The evaluation of the microprocessor.

The microprocessor has changed a lot over the years, says (Michael W.
Davidson,http://micro.magnet.fsu.edu/chipshot.html) Microprocessor
technology is progressing so rapidly that even experts in the field are
having trouble keeping up with current advances. As more competition
develops in this $150 billion a year business, power and speed of the
microprocessor is expanding at an almost explosive rate. The changes
have been most evident over the last decade. The microprocessor has
changed the way computers work by making them faster. The
microprocessor is often called the brain of the C.P.U.(or the central
processing unit)and without the microprocessor the computer is more or
less useless. Motorola and Intel have invented most of the
microprocessors over the last decade. Over the years their has been a
constant battle over cutting edge technology. In the 80's Motorola won
the battle, but now in the 90's it looks as Intel has won the war.

The microprocessor 68000 is the original microprocessor(Encarta 95). It
was invented by Motorola in the early 80's. The 68000 also had two very
distinct qualities like 24-bit physical addressing and a 16-bit data
bus. The original Apple Macintosh ,released in 1984, had the 8-MHz
found at the core of it. It was also found in the Macintosh Plus, the
original Macintosh SE, the Apple Laser-Writer IISC, and the Hewlett-
Packard's LaserJet printer family. The 68000 was very efficient for its
time for example it could address 16 megabytes of memory, that is 16
more times the memory than the Intel 8088 which was found in the IBM PC
. Also the 68000 has a linear addressing architecture which was better
than the 8088's segmented memory architecture because it made making
large applications more straightforward.

The 68020 was invented by Motorola in the mid-80's(Encarta 95). The
68020 is about two times as powerful as the 68000. The 68020 has 32-bit
addressing and a 32-bit data bus and is available in various speeds like
16MHz, 20MHz, 25MHz, and 33MHz. The microprocessor 68020 is found in the
original Macintosh II and in the LaserWriter IINT both of which are from
Apple.
The 68030 microprocessor was invented by Motorola about a year after the
68020 was released(Encarta 95). The 68030 has 32-bit addressing and a
32-bit data bus just like it's previous model, but it has paged memory
management built into it, delaying the need for additional chips to
provide that function. A 16-MHz version was used in the Macintosh IIx,
IIcx, and SE/30. A 25-MHz model was used in the Mac IIci and the NeXT
computer. The 68030 is produced in various versions like the 20-MHz,
33MHz, 40-MHz, and 50MHz.

The microprocessor 68040 was invented by Motorola(Encarta 95). The
68040 has a 32-bit addressing and a 32-bit data bus just like the
previous two microprocessors. But unlike the two previous
microprocessors this one runs at 25MHz and includes a built-in floating
point unit and memory management units which includes 4-KB instruction
and data coaches. Which just happens to eliminate the need additional
chips to provide these functions. Also the 68040 is capable of parallel
instruction execution by means of multiple independent instruction
pipelines, multiple internal buses, and separate caches for both data
and instructions.

The microprocessor 68881 was invented by Motorola for the use with both
microprocessor 68000 and the 68020(Encarta 95). Math coprocessors, if
supported by the application software, would speed up any function that
is math-based. The microprocessor 68881 does this by additional set of
instructions for high-proformance floating point arithmetic, a set of
floating-point data registers, and 22 built-inconstants including p and
powers of 10. The microprocessor 68881 conforms to the ANSI/IEEE 754-
1985 standard for binary floating-point arithmetic. When making the
Macintosh II, Apple noticed that when they added a 68881, the
improvement in performance of the interface, and thus the apparent
performance was changed dramatically. Apple then decided to add it as
standard equipment.

The microprocessor 80286, also called the 286was invented by Motorola in
1982(Encarta 95). The 286 was included in the IBM PC/AT and compatible
computers in 1984. The 286 has a 16-bit resister, transfers information
over the data bus 16 bits at a time, and use 24 bits to address memory
location. The 286 was able to operate in two modes real (which is
compatible with MS-DOS and limits the 8086 and 8088 chips) and protected
( which increases the microprocessor's functionality). Real mode limits
the amount of memory the microprocessor can address to one megabyte; in
protected mode, however the addressing access is increased and is
capable of accessing up to 16 megabytes of memory directly. Also, an
286 microprocessor in protected mode protects the operating system from
mis-behaved applications that could normally halt (or "crash") a system
with a non-protected microprocessor such as the 80286 in real mode or
just the plain old 8088.

The microprocessor 80386dx also called the 386 or the 386dx was invented
in 1985(Encarta 95). The 386 was used in IBM and compatible
microcomputers such as the PS/2 Model 80. The 386 is a full 32-bit
microprocessor, meaning that it has a 32-bit resister, it can easily
transfer information over its data bus 32 bits at a time, and it can use
32 bits in addressing memory. Like the earlier 80286, the 386 operates
in two modes, again real (which is compatible with MS-DOS and limits the
8086 and 8088 chips) and protected ( which increases the
microprocessor's functionality and protects the operating system from
halting because of an inadvertent application error.) Real mode limits
the amount of memory the microprocessor can address to one megabyte; in
protected mode, however the total amount of memory that the 386 can
address directly is 4 gigabytes, that is roughly 4 billion bytes. The
80386dx also has a virtual mode, which allows the operating systems to
effectively divide the 80386dx into several 8086 microprocessors each
having its own 1-megabyte space, allowing each "8086" to run its own
program.

The microprocessor 80386sx also called the 386sx was invented by Intel
in 1988 as a low-cost alternative to the 80386DX(Encarta 95). The
80386SX is in essence an 80386DX processor limited by a 16-bit data bus.
The 16-bit design allows 80386SX systems to be configured from less
expensive AT-class parts, ensuring a much lower complete system price.
The 80386SX offers enhanced performance over the 80286 and access to
software designed for the 80386DX. The 80386SX also offers 80386DX
comforts such as multitasking and virtual 8086 mode.


The microprocessor 80387SX also called the 387SX was invented by
Intel(Encarta 95). A math, or floating-point, coprocessor from Intel
for use with the 80386SX family of microprocessors. The 387sx is
available in a 16-MHz version only, the 80387SX, if supported by the
application software, can dramatically improve system performance by
offering arithmetic, trigonometric, exponential, and logarithmic
instructions for the application to use-instructions not offered in the
80386SX instruction set. The 80387SX also offers perfect operations for
sine, cosine, tangent, arctangent, and logarithm calculations. If used,
these additional instructions are carried out by the 80387SX, freeing
the 80386SX to perform other tasks. The 80387SX is capable of working
with 32- and 64-bit integers, 32-, 64-, and 80-bit floating-point
numbers, and 18-digit BCD (binary coded decimal) operands; it coincides
to the ANSI/IEEE 754-1985 standard for binary floating-point arithmetic.
The 80387SX operates individually on the 80386SX's mode, and it performs
as expected regardless of whether the 80386SX is running in real,
protected, or virtual 8086 mode.

The microprocessor mi486 also called the 80486 or the 486 was invented
in 1989 by Intel(Encarta 95). Like its 80386 predecessor, the 486 is a
full-bit processor with 32-bit registers, 32-bit data bus, and 32-bit
addressing. It includes several enhancements, however, including a
built-in cache controller, the built-in equivalent of an 80387 floating-
point coprocessor, and provisions for multiprocessing. In addition, the
486 uses a "pipeline" execution scheme that breaks instructions into
multiple stages, resulting in much higher performance for many common
data and integer math operations.

In conclusion it is evident by the following that microprocessors are
developing at leaps and bounds and it is not surprising that if by the
time it hits the teacher's desk or by the time you read this the next
superchip will be developed(Encarta 95).