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 faster.
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