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.ec] # APPENDIX C - GLOSSARY
.bp
.np
.ce
APPENDIX C - GLOSSARY
.sp1
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ACCESS TIME]>The time required to ACCESS TIME
locate and read or write data on a The time required to locate and read or write data on a direct access storage
direct access storage device, such as device, such as a diskette drive.
a diskette drive.
ADDRESS]>The numeric location of a ADDRESS
piece of data in memory. Usually The numeric location of a piece of data in memory. Usually given as a
given as a hexadecimal number from hexadecimal number from $0000 to $FFFF (65535 decimal). A disk address is the
$0000 to $FFFF (65535 decimal). A location of a data sector, expressed in terms of its track and sector numbers.
disk address is the location of a
data sector, expressed in terms of its
track and sector numbers.
ALGORITHM]>A sequence of steps which ALGORITHM
may be performed by a program or A sequence of steps which may be performed by a program or other process, which
other process, which will produce a will produce a given result.
given result.
ALPHANUMERIC]>An alphabetic character ALPHANUMERIC
(A-Z) or a numeric digit (0-9). The An alphabetic character (A-Z) or a numeric digit (0-9). The term used to refer
term used to refer to the class of all to the class of all characters and digits.
characters and digits.
ANALOG]>As opposed to digital. ANALOG
Having a value which is continuous, As opposed to digital. Having a value which is continuous, such as a voltage or
such as a voltage or electrical electrical resistance.
resistance.
AND]>The logical process of AND
determining whether two bits are both The logical process of determining whether two bits are both ones. 0 AND 1
ones. 0 AND 1 results in 0 (false), results in 0 (false), 1 AND 1 results in 1 (true).
1 AND 1 results in 1 (true).
ARM]>The portion of a disk drive ARM
which suspends the read/write head The portion of a disk drive which suspends the read/write head over the disk's
over the disk's surface. The arm can surface. The arm can be moved radially to allow access to different tracks.
be moved radially to allow access to
different tracks.
ASCII]>American Standard Code for ASCII
Information Interchange. A American Standard Code for Information Interchange. A hexadecimal to character
hexadecimal to character conversion conversion code assignment, such that the 256 possible values of a single byte
code assignment, such that the 256 may each represent a alphabetic, numeric, special, or control character. ASCII
possible values of a single byte may is used when interfacing to peripherals, such as keyboards, printers, or video
each represent a alphabetic, numeric, text displays.
special, or control character. ASCII
is used when interfacing to
peripherals, such as keyboards,
printers, or video text displays.
ASSEMBLY LANGUAGE]>Also known as ASSEMBLY LANGUAGE
MACHINE LANGUAGE. The native Also known as MACHINE LANGUAGE. The native programming language of the
programming language of the individual computer. Assembly language is oriented to the machine, and is not
individual computer. Assembly humanized, as is BASIC, PASCAL, or FORTRAN. An assembler is used to convert
language is oriented to the machine, assembly language statements to an executable program.
and is not humanized, as is BASIC,
PASCAL, or FORTRAN. An assembler is
used to convert assembly language
statements to an executable program.
BACKUP]>The process of making a copy BACKUP
of a program or data against the The process of making a copy of a program or data against the possibility of its
possibility of its accidental loss or accidental loss or destruction.
destruction.
BASE]>The number system in use. BASE
Decimal is base 10, since each digit The number system in use. Decimal is base 10, since each digit represents a
represents a power of 10 power of 10 (1,10,100,...). Hexadecimal is base 16 (1,16,256,...). Binary is
(1,10,100,...). Hexadecimal is base base 2 (1,2,4,8,...).
16 (1,16,256,...). Binary is base 2
(1,2,4,8,...).
BINARY]>A number system based upon BINARY
powers of 2. Only the digits 0 and 1 A number system based upon powers of 2. Only the digits 0 and 1 are used. 101
are used. 101 in binary, for in binary, for example, is 1 units digit, 0 twos, and 1 fours, or 5 in decimal.
example, is 1 units digit, 0 twos,
and 1 fours, or 5 in decimal.
BIT]>A single binary digit (a 1 or a BIT
0). A bit is the smallest unit of A single binary digit (a 1 or a 0). A bit is the smallest unit of storage or
storage or information in a computer. information in a computer.
BIT CELL]>The space on a diskette, BIT CELL
between two clock pulses, which can The space on a diskette, between two clock pulses, which can hold the value of a
hold the value of a single binary 0 single binary 0 or 1 (bit).
or 1 (bit).
BIT SLIP MARKS]>The epilogue of a BIT SLIP MARKS
disk field. Used to double check The epilogue of a disk field. Used to double check that the disk head is still
that the disk head is still in read in read sync and the sector has not been damaged.
sync and the sector has not been
damaged.
BOOT/BOOTSTRAP]>The process of BOOT/BOOTSTRAP
loading a very large program into The process of loading a very large program into memory by loading successively
memory by loading successively larger larger pieces, each of which loads its successor. The program loads itself by
pieces, each of which loads its "pulling itself up by its bootstraps".
successor. The program loads itself
by "pulling itself up by its
bootstraps".
BRK]>BREAK. An assembly langauge instruction BRK
which can be used to force an BREAK. An assembly langauge instruction which can be used to force an interrupt
interrupt and immediate suspension of and immediate suspension of execution of a program.
execution of a program.
BUFFER]>An area of memory used to BUFFER
temporarily hold data as it is being An area of memory used to temporarily hold data as it is being transferred to or
transferred to or from a peripheral, from a peripheral, such as a disk drive.
such as a disk drive.
BUG]>A programming error. Faulty BUG
operation of a program. A programming error. Faulty operation of a program.
BYTE]>The smallest unit of BYTE
addressable memory in a computer. A The smallest unit of addressable memory in a computer. A byte usually consists
byte usually consists of 8 bits and of 8 bits and can contain a decimal number ranging from 0 to 255 or a single
can contain a decimal number ranging
from 0 to 255 or a single
alphanumeric character. alphanumeric character.
CARRIAGE RETURN]>A control character CARRIAGE RETURN
which instructs the printer to end A control character which instructs the printer to end one line and begin
one line and begin another. When another. When printing a carriage return is usually followed by a line feed.
printing a carriage return is usually
followed by a line feed.
CARRY FLAG]>A 6502 processor flag CARRY FLAG
which indicates that a previous A 6502 processor flag which indicates that a previous addition resulted in a
addition resulted in a carry. Also carry. Also used as an error indicator by many system programs.
used
as an error indicator by many system
programs.
CATALOG]>A directory of the files on CATALOG
a diskette. See DIRECTORY. A directory of the files on a diskette. See DIRECTORY.
CHAIN]>A linked list of data CHAIN
elements. Data is chained if its A linked list of data elements. Data is chained if its elements need not be
elements need not be contiguous in contiguous in storage and each element can be found from its predecessor via an
storage and address pointer.
each element can be found from its
predecessor via an address pointer.
CHECKSUM/CRC]>A method for verifying CHECKSUM/CRC
that data has not been damaged. When A method for verifying that data has not been damaged. When data is written,
data is written, the sum of all its the sum of all its constituent bytes is stored with it. If, when the data is
constituent bytes is stored with it. later read, its sum no longer matches the checksum, it has been damaged.
If, when the data is later read, its
sum no longer matches the checksum,
it has been damaged.
CLOBBERED]>Damaged or destroyed. A CLOBBERED
clobbered sector is one which has Damaged or destroyed. A clobbered sector is one which has been overwritten such
been overwritten such that it is that it is unrecoverable.
unrecoverable.
CODE]>Executable instructions to the CODE
computer, usually in machine Executable instructions to the computer, usually in machine language.
language.
COLDSTART]>A restart of a program COLDSTART
which reinitializes all of its A restart of a program which reinitializes all of its parameters, usually
parameters, usually erasing any work erasing any work which was in progress at the time of the restart. A DOS
which was in progress at the time of coldstart erases the BASIC program in memory.
the restart. A DOS coldstart erases
the BASIC program in memory.
CONTIGUOUS]>Physically next to. Two CONTIGUOUS
bytes are contiguous if they are Physically next to. Two bytes are contiguous if they are adjoining each other
adjoining each other in memory or on in memory or on the disk.
the disk.
CONTROL BLOCK]>A collection of data CONTROL BLOCK
which is used by the operating system A collection of data which is used by the operating system to manage resources.
to manage resources. Examples of a Examples of a control block used by DOS are the file buffers.
control block used by DOS are the
file buffers.
CONTROL CHARACTER]>A special ASCII CONTROL CHARACTER
code which is used to perform a A special ASCII code which is used to perform a unique function on a peripheral,
unique function on a peripheral, but but does not generate a printable character. Carriage return, line feed, form
does not generate a printable feed, and bell are all control characters.
character.
Carriage return, line feed, form
feed, and bell are all control
characters.
CONTROLLER CARD]>A hardware circuit CONTROLLER CARD
board which is plugged into an APPLE A hardware circuit board which is plugged into an APPLE connector which allows
connector which allows communication communication with a peripheral device, such as a disk or printer. A controller
with a peripheral device, such as a card usually contains a small driver program in ROM.
disk or printer. A controller card
usually contains a small driver
program in ROM.
CSWL]>A vector in zero-page through CSWL
which output data is passed for A vector in zero-page through which output data is passed for display on the CRT
display on the CRT or for printing. or for printing.
CYCLE]>The smallest unit of time CYCLE
within the central processor of the The smallest unit of time within the central processor of the computer. Each
computer. Each machine language machine language instruction requires two or more cycles to complete. One cycle
instruction requires two or more (on the APPLE) is one micro-second or one millionth of a second.
cycles to complete. One cycle (on
the APPLE) is one micro-second or one
millionth of a second.
DATA]>Units of information. DATA
Units of information.
DATA SECTOR BUFFER]>On the APPLE, a DATA SECTOR BUFFER
256 byte buffer used by DOS to hold On the APPLE, a 256 byte buffer used by DOS to hold the image of any given
the image of any given sector on the sector on the diskette. As information is read from the file, data is extracted
diskette. As information is read from the data sector buffer until it is exhausted, at which time it is refilled
from the file, data is extracted from with the next sector image.
the data sector buffer until it is
exhausted, at which time it is
refilled with the next sector image.
DATA TYPE]>The type of information DATA TYPE
stored in a byte. A byte might The type of information stored in a byte. A byte might contain a printable
contain a printable ASCII character, binary ASCII character, binary numeric data, or a machine language instruction.
numeric data, or a machine language
instruction.
DCT]>Device Characteristics Table. DCT
Used as an input parameter table to Device Characteristics Table. Used as an input parameter table to Read/Write
Read/Write Track/Sector (RWTS) to Track/Sector (RWTS) to describe the hardware characteristics of the diskette
describe the hardware characteristics drive.
of the diskette drive.
DECIMAL]>A number system based upon DECIMAL
powers of 10. Digits range from 0 to A number system based upon powers of 10. Digits range from 0 to 9.
9.
DEFERRED COMMANDS]>DOS commands which DEFERRED COMMANDS
may (or must) be invoked from within DOS commands which may (or must) be invoked from within an executing BASIC
an executing BASIC program. OPEN, program. OPEN, READ, WRITE, and CLOSE are all examples of deferred commands.
READ, WRITE, and CLOSE are all
examples of deferred commands.
DIGITAL]>As opposed to analog. DIGITAL
Discrete values as opposed to As opposed to analog. Discrete values as opposed to continuous ones. Only
continuous ones. Only digital values digital values may be stored in a computer. Analog measurements from the real
may be stored in a computer. Analog world, such as a voltage or the level of light outside, must be converted into a
measurements from the real world, numerical value which, of necessity, must be "rounded off" to a discrete value.
such as a voltage or the level of
light outside, must be converted into
a numerical value which, of
necessity, must be "rounded off" to a
discrete value.
DIRECT ACCESS]>Peripheral storage DIRECT ACCESS
allowing rapid access of any piece of Peripheral storage allowing rapid access of any piece of data, regardless of its
data, regardless of its placement on placement on the medium. Magnetic tape is generally not considered direct
the medium. Magnetic tape is access, since the entire tape must be read to locate the last byte. A diskette
generally not considered direct is direct access, since the arm may be rapidly moved to any track and sector.
access, since the entire tape must be
read to locate the last byte. A
diskette is direct access, since the
arm may be rapidly moved to any
track and sector.
DIRECTORY]>A catalog of all files DIRECTORY
stored on a diskette. The directory A catalog of all files stored on a diskette. The directory must contain each
must contain each file's name and its file's name and its location on the disk as well as other information regarding
location on the disk as well as other the type of data stored there.
information regarding the type of
data stored there.
DISK INITIALIZATION]>The process DISK INITIALIZATION
which places track formatting The process which places track formatting information, including sectors and
information, including sectors and gaps, on a blank diskette. During disk initialization, DOS also places a VTOC
gaps, on a blank diskette. and directory on the newly formatted disk, as well as saving the HELLO program.
During disk initialization, DOS also
places a VTOC and directory on the
newly formatted disk, as well as
saving the HELLO program.
DISPLACEMENT]>The distance from the DISPLACEMENT
beginning of a block of data to a The distance from the beginning of a block of data to a particular byte or
particular byte or field. field. Displacements are usually given beginning with 0, for the first byte, 1
Displacements are usually given for the second, etc. Also known as an offset.
beginning with 0, for the first byte,
1 for the second, etc. Also known as
an offset.
DRIVER]>A program which provides an DRIVER
input stream to another program or an A program which provides an input stream to another program or an output device.
output device. A printer driver A printer driver accepts input from a user program in the form of lines to be
accepts input from a user program in printed, and sends them to the printer.
the form of lines to be printed, and
sends them to the printer.
DUMP]>An unformatted or partially DUMP
formatted listing of the contents of An unformatted or partially formatted listing of the contents of memory or a
memory or a diskette in hexadecimal. diskette in hexadecimal. Used for diagnostic purposes.
Used for diagnostic purposes.
ENCODE]>To translate data from one ENCODE
form to another for any of a number To translate data from one form to another for any of a number of reasons. In
of reasons. In DOS 3.3, DOS 3.3, Data is encoded from 8 bit bytes to 6 bit bytes for storage on a DISK
Data is encoded from 8 II.
bit bytes to 6 bit bytes for storage
on a DISK II.
ENTRY POINT (EPA)]>The entry point ENTRY POINT (EPA)
address is the location within a The entry point address is the location within a program where execution is to
program where execution is to start. start. This is not necessarily the same as the load point (or lowest memory
This is not necessarily the same as
the load point (or lowest memory
address in the program). address in the program).
EOF]>End Of File. This mark signals EOF
the end of a data file. $00 for End Of File. This mark signals the end of a data file. $00 for APPLE DOS text
APPLE DOS text files. files.
EPILOGUE]>The last three bytes of a EPILOGUE
field on a track. These unique bytes The last three bytes of a field on a track. These unique bytes are used to
are used to insure the integrity of insure the integrity of the data which preceeds them.
the data which preceeds them.
EXCLUSIVE OR]>A logical operation EXCLUSIVE OR
which compares two bits to determine A logical operation which compares two bits to determine if they are different.
if they are different. 1 EOR 0 1 EOR 0 results in 1. 1 EOR 1 results in 0.
results in 1. 1 EOR 1 results in 0.
FIELD]>A group of contiguous bytes FIELD
forming a single piece of data, such A group of contiguous bytes forming a single piece of data, such as a person's
as a person's name, his age, or his name, his age, or his social security number. In disk formatting, a group of
social security number. In disk data bytes surrounded by gaps.
formatting, a group of data bytes
surrounded by gaps.
FILE]>A named collection of data on a FILE
diskette or other mass storage A named collection of data on a diskette or other mass storage medium. Files
medium. Files can contain data or can contain data or programs.
programs.
FILE BUFFERS]>In APPLE DOS, a FILE BUFFERS
collection of buffers used to manage In APPLE DOS, a collection of buffers used to manage one open file. Included
one open file. Included are a data are a data sector buffer, a Track/Sector List sector buffer, a file manager
sector buffer, a Track/Sector List workarea buffer, the name of the file, and pointers. The DOS command, MAXFILES
sector buffer, a file manager 3, causes 3 of these file buffers to be allocated.
workarea buffer, the name of the
file, and pointers. The DOS command,
MAXFILES 3, causes 3 of these file
buffers to be allocated.
FILE DESCRIPTOR]>A single entry in a FILE DESCRIPTOR
diskette directory which describes A single entry in a diskette directory which describes one file. Included are
one file. Included are the name of the name of the file, its data type, its length, and its location on the
the file, its data type, its length, diskette.
and its location on the diskette.
FILE MANAGER]>That portion of DOS FILE MANAGER
which manages files. The file That portion of DOS which manages files. The file manager handles such general
manager handles such general operations as OPEN, CLOSE, READ, WRITE, POSITION, RENAME, DELETE, etc.
operations as OPEN, CLOSE, READ,
WRITE, POSITION, RENAME, DELETE, etc.
FILE TYPE]>The type of data held by a FILE TYPE
file. Valid DOS file types are The type of data held by a file. Valid DOS file types are Binary, Applesoft,
Binary, Applesoft, Integer-BASIC, Integer-BASIC, Text, Relocatable, S, A, and B.
Text, Relocatable, S, A, and B.
FIRMWARE]>A middle ground between FIRMWARE
hardware and software. Usually used A middle ground between hardware and software. Usually used to describe
to describe micro-code or programs micro-code or programs which have been stored in read-only memory.
which have been stored in read-only
memory.
GAPS]>The spaces between fields of GAPS
data on a diskette. Gaps on an APPLE The spaces between fields of data on a diskette. Gaps on an APPLE diskette
diskette contain self-sync bytes. contain self-sync bytes.
HARD ERROR]>An unrecoverable HARD ERROR
Input/Output error. The data stored An unrecoverable Input/Output error. The data stored in the disk sector can
in the disk sector can never be never be successfully read again.
successfully read again.
HARDWARE]>Physical computer HARDWARE
equipment, as opposed to programs Physical computer equipment, as opposed to programs which run on the equipment.
which run on the equipment. A disk drive is an example of a hardware component.
A disk drive is an example of a
hardware component.
HEAD]>The read/write head on a HEAD
diskette drive. A magnetic pickup, The read/write head on a diskette drive. A magnetic pickup, similar in nature
similar in nature to the head on a to the head on a stereo tapedeck, which rests on the spinning surface of the
stereo tapedeck, which rests on the diskette.
spinning surface of the diskette.
HEXADECIMAL/HEX]>A numeric system HEXADECIMAL/HEX
based on powers of 16. Valid hex A numeric system based on powers of 16. Valid hex digits range from 0 to 9 and
digits range from 0 to 9 and A to F, A to F, where A is 10, B is 11, ... , and F is 15. B30 is 11 256's, 3 16's, and
where A is 10, B is 11, ... , and F 0 1's, or 2864 in decimal. Two hexadecimal digits can be used to represent the
is 15. B30 is 11 256's, 3 16's, and contents of one byte. Hexadecimal is used with computers because it easily
0 1's, or 2864 in decimal. converts with binary.
Two hexadecimal digits can be used to
represent the contents of one byte.
Hexadecimal is used with computers
because it easily converts with
binary.
HIGH MEMORY]>Those memory locations HIGH MEMORY
which have high address values. Those memory locations which have high address values. $FFFF is the highest
$FFFF is the highest memory location. memory location. Also called the "top" of memory.
Also called the "top" of memory.
HIMEM]>APPLE's zero-page address HIMEM
which identifies the first byte past APPLE's zero-page address which identifies the first byte past the available
the available memory which can be memory which can be used to store BASIC programs and their variables.
used to store BASIC programs and
their variables.
IMMEDIATE COMMAND]>A DOS command IMMEDIATE COMMAND
which may be entered at any time, A DOS command which may be entered at any time, especially when DOS is waiting
especially when DOS is waiting for a for a command from the keyboard. Deferred commands are the opposite of
command from the keyboard. Deferred
commands are the opposite of
immediate commands. immediate commands.
INDEX]>A displacement into a table or INDEX
block of storage. A displacement into a table or block of storage.
INSTRUCTION]>A single step to be INSTRUCTION
performed in an assembly language or A single step to be performed in an assembly language or machine language
machine language program. program. Instructions perform such operations as addition, subtraction, store,
Instructions perform such operations or load.
as addition, subtraction, store, or
load.
INTEGER]>As opposed to floating INTEGER
point. A "whole" number with no As opposed to floating point. A "whole" number with no fraction associated with
fraction associated with it. it.
INTERCEPT]>A program which logically INTERCEPT
places itself in the execution path A program which logically places itself in the execution path of another
of another program, or pair of program, or pair of programs. A video intercept is used to re-direct program
programs. A video intercept output from the screen to a printer, for example.
is used to re-direct program output
from the screen to a printer,
for example.
INTERLEAVE]>The practice of selecting INTERLEAVE
the order of sectors on a diskette The practice of selecting the order of sectors on a diskette track to minimize
track to minimize access time due to access time due to rotational delay. Also called "skewing" or interlacing.
rotational delay. Also called
"skewing" or interlacing.
INTERRUPT]>A hardware signal which INTERRUPT
causes the computer to halt execution A hardware signal which causes the computer to halt execution of a program and
of a program and enter a special enter a special handler routine. Interrupts are used to service real-time clock
handler routine. Interrupts are used time-outs, BRK instructions, and RESET.
to service real-time clock
time-outs, BRK instructions, and
RESET.
IOB]>Input/Output Block. A IOB
collection of parameter data, passed Input/Output Block. A collection of parameter data, passed to Read/Write
to Read/Write Track/Sector, Track/Sector, describing the operation to be performed.
describing the operation to be
performed.
I/O ERROR]>Input/Output Error. I/O ERROR
An error which occurs Input/Output Error. An error which occurs during transmission of data to or
during transmission of data to or from a peripheral device, such as a disk or cassette tape.
from a peripheral device, such as a
disk or cassette tape.
JMP]>A 6502 assembly langauge JMP
instruction which causes the computer A 6502 assembly langauge instruction which causes the computer to begin
to begin executing instructions at a executing instructions at a different location in memory. Similar to a GOTO
different location in memory. statement in BASIC.
Similar to a GOTO statement in BASIC.
JSR]>A 6502 assembly langauge JSR
instruction which causes the computer A 6502 assembly langauge instruction which causes the computer to "call" a
to "call" a subroutine. Similar to a subroutine. Similar to a CALL statement in BASIC.
CALL statement in BASIC.
K]>A unit of measurement, usually K
applied to bytes. 1 K bytes is A unit of measurement, usually applied to bytes. 1 K bytes is equivalent to
equivalent to 1024 bytes. 1024 bytes.
KSWL]>A vector in zero-page through KSWL
which input data is passed for A vector in zero-page through which input data is passed for from the keyboard
from the keyboard or a remote or a remote terminal.
terminal.
LABEL]>A name associated with a LABEL
location in a program or in memory. A name associated with a location in a program or in memory. Labels are used in
Labels are used in assembly langauge assembly langauge much like statement numbers are used in BASIC.
much like statement numbers are used
in BASIC.
LATCH]>A component into which the LATCH
Input/Output A component into which the Input/Output hardware can store a byte value, which
hardware can store a byte value, will hold that value until the central processor has time to read it (or vice
which will hold that value until the versa).
central processor has time to read
it (or vice versa).
LINK]>An address pointer in an LINK
element of a linked chain of data or An address pointer in an element of a linked chain of data or buffers.
buffers.
LIST]>A one dimensional sequential LIST
array of data items. A one dimensional sequential array of data items.
LOAD POINT (LP)]>The lowest address LOAD POINT (LP)
of a loaded assembly language The lowest address of a loaded assembly language program -- the first byte
program -- the first byte loaded. loaded. Not necessarily the same as the entry point address (EPA).
Not necessarily the same as the entry
point address (EPA).
LOGICAL]>A form of arithmetic which LOGICAL
operates with binary "truth" or A form of arithmetic which operates with binary "truth" or "false", 1 or 0.
"false", 1 or 0. AND, OR, NAND, NOR, AND, OR, NAND, NOR, and EXCLUSIVE OR are all logical operations.
and EXCLUSIVE OR are all logical
operations.
LOOP]>A programming construction in LOOP
which a A programming construction in which a group of instructions or statements are
group of instructions or statements repeatedly executed.
are repeatedly executed.
LOW MEMORY]>The memory locations with LOW MEMORY
the lowest addresses. $0000 is the The memory locations with the lowest addresses. $0000 is the lowest memory
lowest memory location. Also called location. Also called the "bottom" of memory.
the "bottom" of memory.
LOMEM]>APPLE's zero-page address LOMEM
which identifies the first byte of APPLE's zero-page address which identifies the first byte of the available
the available memory which can be memory which can be used to store BASIC programs and their variables.
used to store BASIC programs and
their variables.
LSB/LO ORDER]>Least Significant Bit LSB/LO ORDER
or Least Significant Byte. The 1's Least Significant Bit or Least Significant Byte. The 1's bit in a byte or the
bit in a byte or the second pair of second pair of hexadecimal digits forming an address. In the address $8030, $30
hexadecimal digits forming an
address. In the address $8030, $30
is the LO order part of the address. is the LO order part of the address.
MASTER DISK]>A DOS diskette which MASTER DISK
will boot in an APPLE II of any size A DOS diskette which will boot in an APPLE II of any size memory and take full
memory and take full advantage of it. advantage of it.
MICROSECOND]>A millionth of a MICROSECOND
second. Equivalent to one cycle of A millionth of a second. Equivalent to one cycle of the APPLE II central
the APPLE II central processor. processor. Also written as "Usec".
Also written as "Usec".
MONITOR]>A machine language program MONITOR
which always resides in the computer A machine language program which always resides in the computer and which is the
and which is the first to receive first to receive control when the machine is powered up. The APPLE monitor
control when the machine is powered resides in ROM and allows examination and modification of memory at a byte
up. The APPLE monitor resides in ROM
and allows examination and
modification of memory at a byte
level. level.
MSB/HI ORDER]>Most Significant Bit or MSB/HI ORDER
Most Significant Byte. The 128's bit Most Significant Bit or Most Significant Byte. The 128's bit of a byte (the
of a byte (the left-most) or the left-most) or the first pair of hexadecimal digits in an address. In the byte
first pair of hexadecimal digits in value $83, the MSB is on (is a 1).
an address. In the byte value $83,
the MSB is on (is a 1).
NULL]>Empty, having no length or NULL
value. A null string is one which Empty, having no length or value. A null string is one which contains no
contains no characters. The null characters. The null control character ($00) produces no effect on a printer
control character ($00) produces no (also called an idle).
effect on a printer (also called an
idle).
NIBBLE/NYBBLE]>A portion of a byte, NIBBLE/NYBBLE
usually 4 bits and represented by a A portion of a byte, usually 4 bits and represented by a single hexadecimal
single hexadecimal digit. $FE digit. $FE contains two nibbles, $F and $E.
contains two nibbles, $F and $E.
OBJECT CODE]>A machine language OBJECT CODE
program in binary form, ready to A machine language program in binary form, ready to execute. Object code is the
execute. Object code is the output output of an assembler.
of an assembler.
OBJECT MODULE]>A complete machine OBJECT MODULE
language program in object code form, A complete machine language program in object code form, stored as a file on a
stored as a file on a diskette. diskette.
OFFSET]>The distance from the OFFSET
beginning of a block of data to a The distance from the beginning of a block of data to a particular byte or
particular byte or field. field. Offsets are usually given beginning with 0, for the first byte, 1 for
Offsets are usually given the second, etc. Also known as a displacement.
beginning with 0, for the first byte,
1 for the second, etc. Also known as
a displacement.
OPCODE]>Operation Code. The three OPCODE
letter mnemonic representing a single Operation Code. The three letter mnemonic representing a single assembly
assembly langauge instruction. JMP langauge instruction. JMP is the opcode for the jump instruction.
is the opcode for the jump
instruction.
OPERATING SYSTEM]>A machine language OPERATING SYSTEM
program which manages the memory and A machine language program which manages the memory and peripherals
peripherals automatically, automatically, simplifying the job of the applications programmer.
simplifying the job of the
applications programmer.
OR]>The logical operation comparing OR
two bits to determine if either of The logical operation comparing two bits to determine if either of them are 1.
them are 1. 1 OR 1 results in 1 1 OR 1 results in 1 (true), 1 OR 0 results in 1, 0 OR 0 results in 0 (false).
(true), 1
OR 0 results in 1, 0 OR 0 results in OVERHEAD
0 (false). The space required by the system, either in memory or on the disk, to manage
either. The disk directory and VTOC are part of a diskette's overhead.
OVERHEAD]>The space required by the
system, either in memory or on the
disk, to manage either. The disk
directory and VTOC are part of a
diskette's overhead.
.br
.nx appendix c.2 .nx appendix c.2