PART 1. SUMMARY OF NUMBER SYSTEMS

Charles J. Fraser

John S. Milne

In the manipulation of data within a computer a two-state numbering system is used. Termed the binary system, and it is based on a simple ON/OFF principle. For the semiconductor integrated circuits which make up the computer system, 5 V denotes ON (or logic level 1) while 0 V denotes OFF (or logic level 0). In practice, a tolerance band is adopted, with 2.4-5 V representing logic 1 and 0-0.8 V logic 0.

The microelectronic devices in the system handle the transfer of information in 1's and 0's, which are referred to as BITs, being a short form for BInary digiT. A group of eight bits is termed a byte and a number of computer systems are based on 8-bit technology with the handling of data codes as 8-bit "words." Sixteen- and 32-bit machines are also available.

The computer operates with three numbering systems, decimal, binary, and hexadecimal (often simply called "hex"). Numerical data would normally be entered by a human operator in decimal form, since this is the most familiar number system. The computer, however, must ultimately convert the decimal number into a binary code, since this is the eventual form in which the number will be processed and stored. The hexadecimal system is an in-between state and represents a particularly compact method of handling binary numbers as groups of four bits.

In binary representation the only possible logic levels are 0 and...