Auditing Information Systems, Second Edition

1.1. CENTRAL PROCESSING UNIT

A central processing unit (CPU) is essentially a box of interconnected electronic circuits. There are literally thousands of CPUs in the world today. They include stand-alone microcomputers such as the IBM family of personal computers and their clones, the Apple Macintosh family of microcomputers, mini and mid-range computers such as the IBM AS/400 and the Compaq Alpha family, mainframe computers such as the IBM System 390 series, and even experimental supercomputers. The brains of these CPUs are computer chips. Among other things, chips determine the speed and efficiency with which computers operate. For computer chips, operating speed is usually measured in terms of megahertz (MHz) and more recently in gigahertz (GHz) and teraflops. One MHz is equivalent to one million operations per second. One GHz is equivalent to one billion operations per second. One teraflop is equivalent to one trillion operations per second. There are hundreds of computer chip manufacturers, both large and small. Some of the more well-known chip manufacturers include IBM, Sun, Intel, Motorola, Hewlett Packard, Advanced Micro Devices, NEC, Hitachi, Compaq, Mitsubishi, and Apple. One of the most widely recognized computer chip manufacturers is Intel, maker of the Pentium® family of chips, which are installed in many personal computers and file servers. Pentium 4 chips enable personal computers to run at speeds over 2.5 GHz.

Recent History of Processing Speeds

In January 1997, ...