The Evolution Of The Microprocessor


Evolution Of The Microprocessor

Only once in a lifetime will a new invention
come about to touch every aspect
of our lives. Such a device that
changes the way we work, live, and play is a special
one, indeed. The Microprocessor
has been around since 1971 years, but in the last few
years it has changed the American calculators
to video games and computers (Givone

1). Many microprocessors have been
manufactured for all sorts of products; some
have succeeded and some have not.

This paper will discuss the evolution and history
of the most prominent 16 and 32 bit microprocessors
in the microcomputer and how
they are similar to and different from
each other.

Because microprocessors are a subject that
most people cannot relate to and do
not know much about, this paragraph will
introduce some of the terms that will be in-
volved in the subsequent paragraphs.

Throughout the paper the 16-bit and 32-bit mi-
croprocessors are compared and contrasted.

The number 16 in the 16-bit microproces-
sor refers how many registers there are
or how much storage is available for the mi-
croprocessor (Aumiaux, 3). The microprocessor
has a memory address such as A16,
and at this address the specific commands
to the microprocessor are stored in the
memory of the computer (Aumiaux, 3).

So with the 16-bit microprocessor there are

576 places to store data. With the

32-bit microprocessor there are twice as many
places to store data making the microprocessor

Another common term which is mentioned
frequently in the paper is the oscil-
lator or the time at which the processors"clock" ticks. The oscillator is the pace
maker for the microprocessor which tells
what frequency the microprocessor can proc-
ess information, this value is measured
in Mega-hertz or MHz. A nanosecond is a
measurement of time in a processor, or
a billionth of a second. This is used to measure
the time it takes for the computer to
execute an instructions, other wise knows as a cy-

There are many different types of
companies of which all have their own family
of processors. Since the individual
processors in the families were developed over a
fairly long period of time, it is hard
to distinguish which processors were introduced in
order. This paper will mention the
families of processors in no particular order. The
first microprocessor that will be discussed
is the family of microprocessors called the

9900 series manufactured by Texas Instruments
during the mid-70s and was developed
from the architecture of the 900 minicomputer
series (Titus, 178). There were five dif-
ferent actual microprocessors that were
designed in this family, they were the

TMS9900, TMS9980A, TMS9981, TMS9985, and
the TMS9940. The TMS9900 was
the first of these microprocessors so
the next four of the microprocessors where simply
variations of the TMS9900 (Titus,

178). The 9900 series microprocessors runs with

64K memory and besides the fact that the

9900 is a 16-bit microprocessor, only 15 of
the address memory circuits are in use
(Titus, 179). The 16th address is used for the
computer to distinguish between word and
data functions (Titus, 179. The 9900 series
microprocessors runs from 300 nanoseconds
to 500 ns from 2MHz to 3.3MHz and
even some variations of the original microprocessor
where made to go up to 4MHz
(Avtar, 115).

The next microprocessor that will
be discussed is the LSI-11 which was pro-
duced from the structural plans of the

PDP-11 minicomputer family. There are three
microprocessors in the LSI-11 family they
are the LSI-11, LSI-11/2, and the much im-
proved over the others is the LSI-11/32
(Titus, 131). The big difference between the

LSI-11 family of microprocessors and other
similar microprocessors of its kind is they
have the instruction codes of a microcomputer
but since the LSI-11 microprocessor
originated from the PDP-11 family it is
a multi-microprocessor (Avtar, 207). The fact
that the LSI-11 microprocessor is a multi-microprocessor
means that many other mi-
croprocessors are used in conjunction
with the LSI-11 to function properly (Avtar,

207). The LSI-11 microprocessor
has a direct processing speed of 16-bit word and 7-
bit data, however the improved LSI-11/22
can directly process 64-bit data (Titus, 131).

The average time that the LSI-11 and LSI-11/2
process at are 380 nanoseconds, while
the LSI-11/23 is clocked at 300 nanoseconds
(Titus, 132). There are some great
strengths that lie in the LSI-11 family,
some of which are the efficient way at which
the microprocessor processes and the ability
to run minicomputer software which leads
to great hardware support (Avtar, 179).

Although there are many strengths to the LSI-

11 family there are a couple of weaknesses,
they have limited memory and the slow-
ness of speed at which the LSI-11 processes
at (Avtar, 179).

The next major microprocessors in
the microcomputing industry were the

Z8001 and Z8002, however when the microprocessor
entered into the market the term

Z8000 was used to mean either or both
of the microprocessors (Titus, 73). So when
describing the features of both the Z8001