APPENDIX D
GLOSSARY OF TERMS

A glossary of computer buzz words will help you understand some of the text you will encounter on your personal computing venture.

ASCII -- Acronym for American Standard Code of Information Interchange. Refers to computer industry standardization of computer binary representation of letters, numbers, symbols and certain control characters, so that information can easily be transferred from one computer or peripheral device to another.

Assembler -- Large machine-language program that translates human coded instructions into binary information the computer can use. Assembly Language instructions are abbreviated English commands (called mnemonic codes) that can be easily memorized and written by the computer user. Assembly Language programming is fast and concise but somewhat cryptic to read.

Banked Memory -- A method of enlarging the usual 64K RAM memory space addressable by 8-bit microprocessors to a much larger range, usually 1/2 to 1 megabyte. To avoid addressing confusion, boards above 64K are switched on only when needed by software control.

Baud -- A term used to define the signalling speed of information in a computer (typically relating to input and output). It is the number of bits of info per second.

Binary -- The two-digit (bit) number system based on 0 and 1. Gates are electronic circuits that are either on or off; these two states can represent the binary bits 0 and 1.

Bit -- A binary digit (0 or 1).

Bootstrap -- A method by which a computer awakens to full awareness once it is turned on. Usually refers to PROM software that initiates this awakening.

Bubble Memory -- Computer memory that does not forget what it knows, even when the power is shut off. Bubble memory is mid-way in price and speed between PROM and floppy disk.

Bug -- An error in the hardware or software of a computer.

Bus -- A power or communication line used in common by many parts of a computer. The S-100 Bus is 100 such parallel common communication lines, each of which is capable of carrying one bit or signal through the entire computer.

Byte -- A string of eight binary bits.

Call -- Any request by a user's program for executive action by the computer Monitor or Operating System.

Central Processing Unit -- The nerve center of a computer; the network of electronic circuits that interprets programs and tells a computer how to carry them out.

Chip -- Computer jargon for the tiny silicon slices used to make electronic memories and other circuits. A single chip may have as many as 30,000 electronic parts!

Circuit Board -- A rigid fiberglass or phenolic card upon which various electronic parts are mounted. Printed or etched copper tracks connect the various parts to one another.

Clock -- The master timing circuit for a microprocessor that synchronizes all its operations. Some microprocessors have tuneable clocks so that its operational speed can be increased or decreased by the user for a particular application.

Code -- See Program.

Compiler -- A language translator program that condenses user-created high-level language programs into something the computer can execute directly in its binary circuitry. See also Interpreter. Some compilers perform syntax abbreviation as an intermediate step and make use of an associated run-time program to perform the final translation of user program to executable binary code.

CPM -- Acronym for Control Program Monitor. One of the most popular microcomputer operating systems.

CPU -- See Central Processing Unit.

CRT -- Acronym for Cathrode Ray Tube; a computer video display terminal (not suitable for ordinary TV reception).

Cursor Control -- Ability to move a video display prompt character to any position on the screen, under either keyboard or software command.

Data -- Information; often numerical information.

Debug -- Correct errors.

Digital Compater -- Calculates with discrete numerical information, as opposed to Analog Computer.

Disk -- See Floppy Disk.

Disk Drive -- Electromechanical mass storage unit.

Diskette -- See Floppy Disk.

DMA -- Direct Memory Access. A method by which data can be transferred between peripheral devices and internal memory without in tervention by the central processor.

DOS -- Disk Operating System. A sophisticated monitor capable of accessing, managing and servicing files and data stored on floppy and hard disk subsystems.

Driver -- A software driver is a series of instructions the computer follows to reformat data for transfer to and from a particular peripheral device. The electrical and mechanical requirements are different from one kind of device to another and the software drivers are used to standardize the format of data between them and the central processor.

Dumb Terminal -- A computer peripheral without any intelligence of its own. The sole function of the terminal is to translate between human visual symbols and keystrokes and the binary language of the computer.

Dynamic Memory -- RAM memory that needs to be refreshed every few milliseconds. Most dynamic RAM boards have on-board refresh logic that relieves the central processor of this tedious task.

Firmware -- Programming built into the computer to make its operation simpler for the user to understand. Firmware is usually supplied by the manufacturer stored in PROM memory units. See Monitor.

Fixed Point -- A convention used to represent non-integer numbers in the computer.

Floating Point -- A convention for representing non-integer numbers in the computer using scientific exponential notation.

Floppy Disk -- A flexible plastic disk coated with the same magnetic material used to make recording tape. The disk stores computer information on fifty or more tracks around its surface.

Flow Chart -- A diagram of geometric shapes connected by arrows that show the progression of a computer program. Flow charts are handy for developing complicated computer programs and illustrating how programs work.

Foreground/Background -- A priority system through which current users' needs are serviced first and other tasks are completed more slowly.

Gate -- A very simple electronic circuit that is always either on or off. Clusters of gates can manipulate binary numbers (0 = off; 1 = on). They can also count, do arithmetic, make decisions and store binary numbers. Gates are the basic building blocks of computers.

Handshaking -- interaction between the central processor and peripheral devices. The devices report their status during data transfers so the processor knows when the operation is completed and more data can be transferred.

Hard Copy -- The permanent printout of a program or its results produced by a printer connected to a computer.

Hard Sector -- Magnetic floppy discs are divided into wedges called sectors which are physically marked by holes punched through the disc to indicate the various sectors. Soft sectoring is a method of determining position of data on the disc by software calculations rather than physical monitoring of the disc.

Hardwar -- The circuit boards and electronic parts inside a computer.

Hexadecimal -- A number system based on powers of 16, and having sixteen digits usually numbered 0 thru 9 and then A thru F. Decimal 178 is represented as B2 in hexadecimal notation. Note that an 8-bit byte can be expressed in two hexadecimal digits.

Input -- The means by which data is entered into a computer. Often a keyboard.

Instruction -- A statement or command that tells a computer what to do.

Integer -- A whole number, positive, negative, or zero.

Interface -- A circuit that controls the flow and format of data between the central processor and peripheral devices.

Interpreter -- The program stored inside a computer that converts BASIC statements into the computer's machine language.

Interrupt -- A signal that interrupts a running program so that some other task can be performed. Sometimes interrupts are given priorities so that the central processor will suspend its current task only if the priority is great enough for immediate execution.

I/O -- Input/Output of information in a computer system.

K -- Short for kilo meaning thousand. Used to designate memory capacity; thus a 4K memory has approximately 4,000 storeage elements.

Keyboard -- A typewriter-like panel of switches and keys used to enter programs and data into a computer.

Language -- A system of programming instructions easily understood by both the programmer and the computer. A program ming language has rules of syntax, which must be followed when writing instructions to the computer. These instructions are translated into machine language instructions, which are sequences of binary numbers and are based on the microprocessor's internal circuitry. Since the circuitry varies from one microprocessor to another, the binary codes are frequently incompatible. The solution to this problem is the higher level language, such as BASIC. With minor variations, a BASIC program written for one computer is understandable to another. This makes it easier for people to share their programing efforts with others.

Line Printer -- See Hard Copy.

Linking Loader -- An executive program which connects different program segments so they may be run in the computer as one unit. A useful piece of software that makes subtasks easily available to a main task.

Macro-Assembler -- An Assembler that allows the user to create and define new computer instructions (called macros).

Mainframe -- The box with power supply, motherboard and (optional) front panel, into which various printed circuit boards may be plugged.

Megabyte -- A million keystrokes; a million characters.

Memory -- Any of the many devices (ROMs, RAMs, floppy disks, magnetic tapes, etc.) that store computer programs and data.

MHz -- Megahertz. One Hertz equals one cycle per second. Notation for the frequency or clock speed of various integrated circuits, e.g., the 8080A operates at 2 MHz and the Z-80 at 4 MHz.

Microprocessor -- The central processing unit of a computer assembled on a single silicon chip.

Microcomputer -- A computer made by combining a microprocessor with some memory. Microcomputers are small in size, not performance.

Modem -- Electronic equipment hard-wired into a telephone line to facilitate connection and disconnection between a computer and remote peripherals.

Monitor -- A small package of software usually stored on PROMs that gives the computer a fundamental interactive intelligence. The Monitor usually contains software routines and I/O drivers needed by the user to operate the system. The Monitor is a kind of executive secretary for the user. It tells the computer how and where to acquire the programs and data, where to store them, and how to run them.

Motherboard -- The central communications bus line. The spinal cord of a microcomputer.

NRZ -- Non Return to Zero, one of several methods for coding digital information on magnetic tape.

Operating System -- A sophisticated monitor often found with floppy disc systems.

Output -- The means by which data leaves a computer. Often a television monitor or printer.

Paper Tape -- A narrow ribbon of paper which contains computer data in the form of punched holes. A hole indicates the bit 1; no hole indicates the bit 0. Paper tape is sometimes used to enter programs into a computer.

Parallel -- A type of interface in which all bits of data in a given byte are transferred simultaneously, using a separate data line for each bit.

Parity Bits -- Used to ensure integrity of data transmitted along communications lines.

Peripheral -- An accessory which can be added to a computer to increase its capability and usefulness (a floppy disk, paper tape unit, etc.)

Personal Computer -- An economical microcomputer designed for use by small businesses, schools and computer hobbyists.

Port -- The physical communication line between the central processor and a peripheral. Each port has a numerical address that the processor uses in communicating through it. 8080/Z-80 microprocessors can address up to 256 input and 256 output ports.

Printed Circuit -- Electrical connections of solder traces between components on an epoxy board material.

Printer -- A computer output mechanism that delivers hard copy data.

Program -- The list of instructions or statements that tells a computer what to do.

Program Cartridge -- Read Only Memory on a printed circuit board enclosed in a cartridge case.

Programmer -- A person who writes programs. Usually a professional.

PROM -- Programmable Read Only Memory. This is computer memory which does not forget what it knows, even when the power is shut off. Some kinds of PROM can be erased and reused: EPROMs, or Erasable PROMs. PROMs are a convenient way for the user to design his own operating system software and other tailor-made monitor routines.

Prompt -- A character displayed by a computer as a signal that it expects a response.

RAM -- (Random Access Memory) A temporary memory, i.e., one in which data can be stored so long as power is applied. RAMs store the data that's typed into the keyboard of a microcomputer.

Real-Time Clock -- A piece of hardware which interrupts the processor at fixed time intervals to synchronize the operations of the computer with events occurring in the outside world, often involving man/computer interaction.

Reentrant Code -- Assembler-generated machine language programs that may be shared simultaneously by any number of users.

Refresh -- A signal sent to dynamic RAM every few milliseconds to help it remember data.

Relocatable Code -- Assembler-generated machine language programs that may be placed anywhere in available computer memory for execution. Relocatable code makes life easier for the small system user who does not possess a full complement of memory boards.

ROM -- (Read Only Memory) A permanent memory, i.e., one in which data is stored permanently whether or not electrical power is applied.

ROM PAC(TM) -- Read Only Memory progammed and packaged on a printed circuit card inside a plastic cartridge.

RS232 -- An industry-wide standard protocol for serial communication between computers and peripheral devices.

Serial -- A type of interface in which all the bits of data in a given byte are lined up sequentially (usually with start, stop and parity-error checking bits at the head and tail of the byte) for transfer along one data line.

Smart Terminal -- A computer peripheral capable of computing functions on its own. Smart terminals can usually be switched on command to dumb terminal mode for conversation with larger computers.

Softaware -- Computer programs written on paper or stored on magnetic tape or a floppy disk.

Standard BASIC -- A set of easy English word instructions used to program a microcomputer.

Statement -- A single line of a computer program containing a single instruction like PRINT, LET, RUN, etc.

Static Memory -- RAM memory that holds information with high reliability as long as power is applied. More expensive than dynamic RAM.

String -- A group of data elements (usually ASCII characters) stored in sequential memory locations and treated as one unit for I/O operations, text editing and other program manipulations.

System -- A complete, integrated and functional computer made up of various hardware components linked harmoniously together and unified by software-programmed intelligence.

Telecommunications -- Communication between computers and peripheral devices over telephone lines.

Terminal -- An input device such as a keyboard; an output device such as a printer or TV monitor; or both.

Timesharing -- A computer system that seems to be performing multiple tasks for a number of users simultaneously. In actuality, the processor is working for only one user at any particular moment, but has been programmed to remember what each user was doing last.

Turn-key -- A computer system ready to perform all tasks the moment you turn it on. Business and accounting software is frequently supplied in ready-to-run form on such a system.

User's Group -- An informal or formal association of persons who own or operate similar or identical computing equipment. User's groups are usually formed to exchange programs and other helpful information.

Vectored Interrupt -- A procedure by which interrupts force the central processor to transfer program control to a particular pre-stored routine that handles and processes the interrupt.

Virtual Memory -- A method by which maxi- and minicomputers appear to the user to have unlimited RAM memory resources. Hard disk storage space is used to extend the mainframe RAM through sophisticated operating system program segmentation techniques.


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