Computer architecture.  The design and construction of a computer that is the basis for designating its platform. 208
Chip package.  The housing for an integrated circuit, a chip package can be a single DIP or PGA, or it can include a circuit board as in a DIMM or SEC. 209
Integrated circuit (IC).  A thin slice of silicon crystal containing microscopic circuit elements such as transistors, wires, capacitors, and resistors; also called chips and microchips. 209
Motherboard.  The circuit board in the computer that houses the chips that control the processing functions. 210
Analog device.  A device that operates on continuously varying data, such as a dimmer switch or a watch with a sweep second hand. 211
Digital device.  A device that works with discrete (distinct or separate) numbers or digits. 211
ASCII American Standard Code for Information Interchange.  A code that represents characters as a series of 1 s and Os. Most computers  use ASCII code to represent text, making it possible to transfer data between computers. 212
Binary number system.  A method for representing numbers using only two digits, 0 and 1. Contrast this system to the decimal system, which uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7,8, and 9. 212
Character data.  Letters, symbols, or numerals that will not be used in arithmetic operations (name, social security number, etc.).212
Numeric data.  Numbers that represent quantities and can be used in arithmetic operations. 212
EBCDIC (Extended Binary-Coded Decimal Interchange Code).  A method by which digital computers represent character data. 213
Address lines.  The circuitry on the data bus that carries a signal indicating the location or address of data. 214
Data bus.  An electronic pathway or circuit that connects the electronic components (mainly the processor and RAM) on a computer's motherboard. 214
Data lines.  The wires in the data bus that carry the signals that represent data. 214
Capacitors.  Electronic circuit components that store an electrical charge; in binary code, a charged capacitor represents an "on" bit, and a discharged one represents an 'off" bit. 215
RAM (Random Access Memory).  A type of computer memory circuit that holds data, program instructions, and the operating system while the computer is on. 215
RAM address.  Like the address on a house, a RAM address identifies a specific area in RAM that can hold data. 215
DIMM.  Short for dual in-line memory module, a DIMM is a small circuit board that holds RAM chips. A DIMM has a 64-bit path to the memory chips. 216
Virtual memory.  A computer's use of hard disk storage to simulate RAM. 217
CMOS memory.  A type of battery-powered integrated circuit that holds semi-permanent configuration data (acronym for complementary metal oxide semiconductor). 218
ROM.  Read-only memory; one or more integrated circuits that contain permanent instructions that the computer uses during the boot process. 218
ROM BIOS.  A small set of basic input/output sys- tem instructions stored in ROM, which cause the computer system to load critical operating files when the user turns on the computer. 218
Plug and play.  The ability of a computer to automatically recognize and adjust the system configuration for a newly added device. 219
Millisecond (ms).  A thousandth of a second. 180 Mils A measurement of the size of an integrated circuit, one mil is .001 inch. 220
Accumulator.  A part of the ALU that holds the results of processing operations until they can be sent to RAM. 221
ALU (arithmetic logic unit).  The part of the CPU that performs arithmetic and logical operations on the numbers stored in its registers. 221
Microprocessor.  An integrated circuit that contains the circuitry for processing data. It is a single chip version of the Central Processing Unit (CPU) found in all computers. 221
Registers.  A sort of "scratch pad" area of the ALU and control unit where data or instructions are moved so that they can be processed. 221
Control unit.  The part of the ALU that directs and coordinates processing. 222
Instruction pointer.  A sort of placeholder that the CPU's control unit uses to keep track of the location of the instructions that are scheduled for processing. 222
Instruction register.  A location in the CPU's control unit that holds a processing instruction retrieved from RAM. 222
Instruction.  Computer code that tells the computer to perform a specific arithmetic, logical, or control operation. 223
Instruction set.  The collection of instructions that a CPU is designed to process. 223
Op code.  Short for operation code, an op code is a command word that designates an operation, such as add (ADD), compare (CMP), or jump (JMP).223
Operands.  An operand is the part of an instruction that specifies the data, or the address of the data, on which the operation is to be performed. 223
Instruction cycle.  The steps followed by a computer to process a single instruction; fetch, interpret, execute, then increment the instruction pointer. 224
Cache.  Special high-speed memory that gives the CPU more rapid access to data (also called RAM cache or cache memory). 226
Megahertz.  Megahertz (MHz) is a measure of frequency equivalent to one million cycles per second.226
System clock.  A device in the computer that emits pulses to establish the timing for all system operations. 226
Word size.  The number of bits the CPU can manipulate at one time, which is dependent on the size of the registers in the CPU and on the num- ber of data lines in the bus. 226
CISC.  A general-purpose microprocessor chip designed to handle a wider array of instructions than a RISC chip. CISC stands for complex instruction set computer. 227
Pipelining.  A technology that allows a processor to begin executing an instruction before completing the previous instruction. 227
RISC (Reduced Instruction Set Computer).  A microprocessor chip designed for rapid and efficient processing of a small set of simple instructions. 227
Parallel computer.  A computer that has more than one processor and can process more than one instruction at a time. Also called non-von-Neumann machines. 228
Parallel processing.  A technique by which two or more processors in a computer perform processing tasks simultaneously. 228
Expansion bus.  The segment of the data bus that transports data between RAM and peripheral devices. 229
input/output.  The circuitry that allows a computer to collect data (input) and the transportation of the results to display, print, or storage devices (output). 229
Expansion card.  A circuit board that is plugged into a slot on a PC motherboard to add extra functions, devices, or ports. 230
Expansion slot.  A socket or "slot" on a PC motherboard designed to hold a circuit board called an expansion card. 230
Modem.  A device that sends and receives data to and from computers over telephone lines. 230
Sound card.  A circuit board that gives the computer the ability to accept audio input from a microphone, play sound files stored on disks and CD-ROMS, and produce audio output through speakers or headphones. 230
AGP.  Short for accelerated graphics port, an AGP is a type of interface, or slot, that provides a high- speed pathway for advanced graphics. 231
ISA (Industry Standard Architecture).  A standard for moving data on the expansion bus. Can refer to a type of slot, a bus, or a peripheral device. An older technology, it is rapidly being replaced by PCI architecture. 231
PCI (Peripheral Component Interconnect).  A method for transporting data on the expansion bus. Can refer to type of data bus, expansion slot, or transport method used by a peripheral device. 231
Expansion port.  A socket into which the user plugs a cable from a peripheral device, allowing data to pass between the computer and the peripheral device. 232
Boot process.  The sequence of events that occurs within a computer system between the time the user starts the computer and the time it is ready to process commands. 234
Power-on self-test (POST).  A diagnostic process that runs during startup to check components of the computer such as the graphics card, RAM, keyboard, and disk drives. 236
Bootable floppy disk.  A disk that contains essential operating system files and that can be used to boot a computer. 237
Default drive.  The drive that a computer attempts to read from or write to unless an alternate drive is specified. 237
Windows Registry.  A crucial data file maintained by the operating system that contains the settings needed by a computer to correctly use any hard- ware and software that has been installed on the system. 238
Safe Mode.  A menu option that appears when Windows is unable to complete the boot sequence. By entering safe mode, a user can gracefully shut down the computer, then try to reboot it. 239