AUTHOR'S PREFACE



     the metal shielding underneath the plastic cover.

BIT, BYTE: A hit is the smallest size division of memory in your
     computer. It is so small that it can hold only one value in it: off
     (zero) or on (one). Eight hits together form a byte; this is the size of
     the memory locations discussed in this book. You will sometimes
     hear programmers talk about a half-byte called a "nybble."

CIO: Central Input/Output routines located in ROM. Controls
     Input/Output Control Block operations. Briefly, CIO handles the
     data input and output through the device driver(s) (also known as
     device handlers), then passes control to those drivers. It's a single
     interface with which to access all peripherals in a device-
     independent manner (i.e., uniform handling of data with no
     regard to the device being accessed). As an example: writing data
     to a disk file is treated in an identical manner as writing data to the
     screen; commas insert blanks between elements and both semi-
     colons and commas suppress the End-Of-Line character (EOL).

DCB: Device Control Block, used by Serial Input/Output.

DL:  Display List. This is a set of instructions which tell the ANTIC chip
     where to find the screen display data and how that data is to be
     placed on the TV screen.
DLI: Display List Interrupt. A DLI causes the display to stop
     processing to temporarily run a user-written routine.

DOS: Disk Operating System. The software loaded from disk file
     DOSSYS that controls all disk I/O. The latest edition of DOS is
     called DOS 2.OS (S for single density).

DUP: Disk Utilities Package. The software loaded from disk file
     DUPSYS that handles the DOS menu functions such as Copy.

FMS (or sometimes DFMS): File Management System portion of
     DOS; a dedicated device driver that controls all I/O operations for
     device "D:".

FP: Floating Point mathematical package in ROM.

I/O: Input/Output.

IOCB: Input/Output Control Block. Area of RAM (locations 832
     to 959) used by CIO to define operations to devices such as the
     disk drive (D:), printer (P:), screen display (S:), keyboard (K:) and
     screen editor (E:). ZIOCB is the page zero IOCB.

IRQ: Interrupt request used for serial port communication,
     peripheral devices, timing and keyboard input. IRQ's are
     processed by the POKEY chip.

NMI: Non-Maskable Interrupt; used for video display and
RESET. NMIs are processed by the ANTIC chip.