Last Updated: November 2003
Chapter 2, Data Representation, provides thorough coverage of the various means computers
use to represent both numerical and character information.
multiplication, and division are covered once the reader has been exposed to number bases
and the typical numeric representation techniques, including one’s complement, two’s
complement, and BCD.
In addition, EBCDIC, ASCII, and Unicode character representations
Fixed and floating point representation are also introduced.
Codes for data
recording and error detection and correction are covered briefly.
This chapter should be covered after Chapter 1, but before Chapters 4 through 11.
Lectures should focus on the following points:
Most students have been exposed to positional number systems and
However, these concepts are crucial to understanding the remainder of
Chapter 2, so they should be covered in detail.
Decimal to binary conversions.
Because the binary number system translates easily into
electronic circuitry, it is important to become familiar with how computer represent values.
Signed versus unsigned numbers.
Representing unsigned numbers in binary form is
much less complicated than dealing with signed numbers.
Signed integer representation.
There are basically three methods for representing signed
numbers: signed magnitude, one's complement, and two's complement.
Each of these
methods should be covered, with the focus on signed magnitude and two's complement
Although people do not often add binary values, performing binary
addition and subtraction helps to reinforce the concepts necessary for understanding data
In particular, these operations illustrate the dangers of overflow conditions.
Floating point representation.
Computers must be able to represent floating point
numbers, and there are numerous possible formats for doing so.
Potential errors that may
result from the limitations of the representation are also important to discuss.
ASCII, EBCDIC, Unicode and BCD are all important character
Lectures should emphasize the similarities and differences among these codes.
Codes for data recording and transmission.
When binary data is written to some sort of
medium or transmitted over long distances,
the binary one's and zero's can become
The Essentials of Computer Organization and Architecture
Linda Null and Julia Lobur
Jones and Bartlett Publishers, 2003