Index and Glossary
Here are the definitions of some of the terms that appear in this document.
Those terms which are also links refer to more detailed explanations found
else where in the document.
Address-The location of a
word of memory in RAM.
Logic Unit. Performs simple operations on one or two
words of data, such as add, subtract, etc...
Bit-The smallest unit of information
the computer can handle. The bit can have two values, 1 or 0, which are
represented by high and low electric voltages, respectively. Bits are
generally grouped into units of eight or sixteen, to form a
byte or a word.
Byte-A group of 8
Clock-A chip on
the motherboard that regulates the timing
of events in the computer.
Clock Cycle-The period of time
it takes the CPU to execute one instruction.
-An area on the CPU that contains the
micro-instructions the processor
Processing Unit. The "brains" of the computer, this chip controls all the
other hardware, and performs all major operations.
Gate-A group of transistor that
performs some function on single bits of data. It is the lowest unit
of digital electronics, from which almost all others are contructed.
intruction stored in RAM. These instructions form
the user's programs, and are interpreted by the
-A sequence of bits that controls all of the operations of the
CPU for one clock cycle.
board that connects all the parts of the computer.
Opcode-A number in a
macro-instruction that specifies what
the instruction should do.
Memory. Temporary memory that stores the current executing program and
the data it is working with. See ROM.
Temporary storage space on the CPU that can be
accessed very quickly.
Only Memory. Contains the start up instructions for a computer. Unlike
RAM the programs stored in ROM cannot be changed.
Word-The largest number of
bits the CPU can process at one
time. In our example, this is sixteen bits, but most computers built
today have a word size of thirty-two or even sixty-four bits.
For more advanced interests
We would like to acknowledge contributions from the following sources:
is a publication that discusses the design, preformance, and application
of microcomputer and microprocessor systems.
Here's a look at the insides of a much more complicated processor design,
the SISC 312 or Simple
Insturction Set Chip.
For an example of an asynchrounous microprocessor, check out the
To see a different approach to designing a microprocessor, check out the
RISC (Reduced Instruction Set Chip) architecture, as used in the
R8000 Microprocessor and in
This web site was tested on Netscape Navigator 2.0 and 3.0b6, as well as
Mosiac and the MicroSoft(tm) Internet Explorer. While it displays properly
on all of them, it looks much nicer on Netscape. The pictures were scanned
in with a DeskJet 550 scanner using DeskScan, and touched up with Adobe
Photoshop 3.0. The layout of the processor was drawn by hand using Adobe.
The java code was written and tested on a Windows 95 platform, using
Sun's(tm) Java Develoment Kit 1.0.1 and later 1.0.2.
Questions and Answers]
Donald Hyatt: our team coach. Thanks for life, the universe,
Structured Computer Organization by Andrew S. Tanenbaum,
for information and design concepts.
Mr. Stueben, Mrs. Rittman and Mr. Samson: our CS teachers who have
(along with Mr. Hyatt) taught us everything we know about computers.
For comments or suggestions,
write to us.