ERIC Number: ED440862
Record Type: RIE
Publication Date: 1998-Aug
A Graphical Teaching Tool for Understanding Two's Complement.
Luck, Carlos L.
As part of the Electrical Engineering program at the Univesity of Southern Maine, students are typically introduced to Two's Complement algebra and representation, a method to include negative numbers in the binary representation of integers that is widely used in microprocessors and related digital systems. The traditional, procedural method to generate and evaluate the binary pattern of negative numbers is often perceived to be nonintuitive and time-consuming when students perform it by hand. A graphical method for the representation of binary numbers using Two's Complement algebra was presented to an introductory class on microprocessors with great success. The method is based on the principle of operation of the mechanical odometer and is particularly suited for such tasks as quick and reliable generation/evaluation of "small" negative numbers (-1, -2, etc.), detecting typical microprocessor conditions such as carry and overflow, and performing the common arithmetic operations of adding, subtracting, incrementing and decrementing. Two important educational goals were achieved with this method. First, the graphical representation allowed the students to grasp the principles rather than to focus on the process. Second, the ability to quickly and reliably generate small negative numbers proved to be a valuable skill for assembly programming in the laboratory, since small address offsets are commonplace in branching instructions. Contains 10 references. (Author/CCM)
Publication Type: Reports - Descriptive; Speeches/Meeting Papers
Education Level: N/A
Authoring Institution: N/A
Note: Paper presented at the International Conference of Engineering Education (Rio de Janiero, Brazil, August 1998).