"The Atari A to Z"
by Mark S Baines
Copyright (c) 1998 Mark S Baines
All Rights Reserved
YOU MUST READ "READ_ME.NOW" BEFORE YOU LOOK AT ANY OF THIS FILE
*****************************************************************************
R
Radio button
One of a set of WIMP/GUI graphic devices that, when selected, de-selects the
others in that set so that only one may be selected at a time.
Radio frequency - RF
A frequency in the range of about 10 kHz to 100,000 MHz used for radio
transmission.
Radio frequency interference - RFI
A possible source of data corruption in unshielded data carrying cables and
interference on radio and TV reception. See EMI.
Radix
Synonymous with base, the amount by which a digit is multiplied or divided
when moved to an adjacent digit position.
Ragged text
Printed text which is flush with the left margin and uneven on the right
margin.
Rail
The electric power distribution bus on a circuit board.
RAM
Random Access Memory. High-speed, read-write memory usually referring to
volatile semiconductor memory of dynamic or static type.
RAM disk
A section of RAM set up to behave as a virtual disk drive although, because it
is volatile memory and unlike a real disk drive, the contents are lost when
the computer is turned off. RAM disks have the advantage of being faster than
floppy or hard disk drives.
Random access
An access in which the time taken to read and write data is a constant that
does not depend on the location being accessed within the memory.
Random number
A number derived from a set in such a way that it has an equal probability of
being any number in that set.
Range
All the values between an upper and lower limit that a function or variable
can take. Also, all the instructions executed with each iteration of a loop.
Rank
To arrange in order according to priority or importance.
Raster
A coordinate grid of addressable points containing all possible positions on a
cathode ray tube display screen. Also, a scan line on such a screen.
Raster scan
A term denoting a line-by-line scan method of producing a display on a CRT
screen. The display image is held in memory with, say, a word of memory for
each addressable point or pixel each containing its on/off state, brightness
and colour attributes. Raster scans are characterized by jagging, the stair-
step diagonal lines.
Rate
Also frequency, the number of occurrences of an event per unit time.
Raw data
Data as received on source documents, on which no processing has been
performed.
R & D
Research and Development.
RDBMS
Relational DataBase Management System. A DBMS that can handle more than one
database file at the same time and enable the user to obtain data (for a
report, for instance) from individual records anywhere in those files.
Read
To convert data from a static form, say on disk or RAM, to a sequence of
signals, the purpose being to write the data to some other location usually in
a different form.
README file
A text file, often supplied with programs, for the user's immediate attention
usually containing up-to-date and/or important information. Variously called
README, READ_ME, READ_ME.TXT etc.
Read in
Sometimes load. To receive data in a storage location, usually from backing
storage to main memory.
Read-only
An access restriction that prevents writing to a particular location of
memory. A file may be read-only, thus preventing a user from altering or
deleting that file's contents.
Read-only memory
See ROM.
Read-out
A display of data in character form on a screen or paper.
Read/write access
An access mode that permits a user to read and/or write data to a storage
location.
Read/write head
A device used for both reading and writing data from and to a magnetizable
surface, such as in a tape or disk drive.
Reader
A device that converts data from a static form to electrical pulses for
transfer, i.e. an OCR.
Real
A numeric value as represented by decimal digits, a decimal point and a sign
(+/-). Also, not virtual but physical.
Real-time
A term applied to a system where outputs and results are produced as soon as
inputs are received without any appreciable time lag.
Real-time clock
The Ricoh RP5C15 chip in the Mega ST and the Motorola MC146818A chip in the TT
and Falcon providing the time of day and date as used by TOS for file
maintenance and other operations. The operation of the chip is maintained by
batteries when the computer is switched off. These chips bypass the IKBD clock
which is never used. The RTC on a TT and Falcon also has 50 bytes of battery
backed non-volatile RAM which is used for storing diagnostic and configuration
data.
Receive
To accept something (a message, data, signal) that has been sent by another
device.
Recognition
A machine operation of examining and interpreting data in some 'natural' form,
such as print, speech, sound, video images etc.
Record (verb)
To place data on a storage medium, usually a magnetizable surface storage
device.
Record (noun)
A group of related fields considered as a unit for access and processing by a
database system. Those fields are usually concerned with a particular entity,
such as an employee or invoice.
Recording
The process of converting electrical signals to a static form, usually to a
magnetizable surface.
Recording density
The number of bits stored per unit area, volume, or length of track of a
storage medium, although it is usually the number of bits per inch of track of
a magnetizable surface.
Recoverable error
An error detected in one reading of data and not in a subsequent one, or an
error that does not result in the loss of data or termination of a program.
Recovery
The operation of reversing the effects of an error. Also, returning a system
to an operable condition following a failure.
Recovery routine
A routine that is entered when an error occurs to isolate it, assess its
extent, perform steps to resolve it and output a user message.
Recovery time
Referring to an electronic circuit or device with two modes of operation that
uses circuit elements in common, the time required to resume one mode after
having been in the other.
Recursive operation
An operation performed in several stages in which each stage (except the
first) uses the output of the previous one as input.
Recursive routine
A routine performing a recursive operation or that calls itself when it has
finished each execution until interrupted.
Redirection
To cause input and output to be sent to a program or a device other than that
normally prescribed. Under TOS, .TTP programs can normally have their output
redirected from the screen to a disk file with a command such as '>
filename.txt' at the end of the program's normal parameter list. In CLI
environments, such commands are easy and commonly used. Using MultiTOS and
Mintshel I/O redirection is supported for external commands. To redirect the
output of a command to a file, use '> file'; to append to a file use '>>
file'; and to redirect input from a file use '< file'. In addition, use '>&
file' or '>>& file' to redirect both stdout and stderr to file, and '2> file'
or '2>> file' to redirect just stderr. For instance, 'prog args 2> err > out'
will redirect stderr to err and stdout to out.
Redundancy
The condition in which bits or characters that have no data significance are
added to a unit of data for purposes of error detection and recovery, e.g.
parity bits. Also, the percentage of a block of data that consists of such
bits or characters.
Redundancy check
A check of redundant bits or characters to determine if they conform to some
predesignated pattern and thus to indicate whether or not an error has
occurred in the data to which they are attached.
Re-entrant
A term applied to a sequence of instructions that contain no values that are
changed during execution or reset prior to execution. Such a sequence can be
executed repeatedly by the same program.
Reference
A term applied to relatively permanent units of code or data which are used
for comparison or calibration purposes.
Refresh
To maintain a particular display on a CRT screen by repeated scans of the
electron beam, requiring a refresh store. Also, on dynamic RAM, to provide
repetitive electrical pulses at short intervals to refresh the capacitive
charge on gates where 1-bits have been written, so retaining the data. This is
performed by the MMU or MCU.
Refresh rate
The number of times the display is refreshed on the screen, for instance, 71.4
times per second on a ST monochrome screen and 50 or 60 Hz on a ST colour
screen. On the TT all colours modes are 60 Hz and 67 Hz for monochrome mode.
Refresh store
The section of memory in which a display image is held in bit-pattern form and
which is scanned as a step to modulating the electron beam to maintain that
image on a CRT screen.
Register
A storage location of standard length, with associated electronic circuitry to
permit selected bits to be read and written or moved between bit positions.
They are essential elements of a CPU, holding data and addresses and other
temporary values required during processing.
Relational database
A database where the data has relationships with other data in other files.
Such links between fields and records allow the construction of reports
utilizing the data from more than one file. See RDBMS.
Relational operator
An operator that specifies a comparison between two numeric values with a
result that is either true or false, such as the operators 'equal to', 'not
equal to', 'less than' and 'greater than'.
Relative address
An address value that is a displacement from a base address.
Relocatable program
A program that is designed to load and run from any memory location, where all
addresses are relative, such as in the ST and TT. Most programs on 8-bit
computers, such as the Spectrum, are not relocatable having to be loaded at a
specified address every time.
Remote
A device or operation that is geographically separated from a computer but
communicating with it.
Remote access
Access to a program or data made from a remote terminal or computer.
Remote station
A data station in a network other than the main computer.
Reorganize
To make copies of data in such a way so as to reduce its access time and
storage space. Such processes are commonly done on database records that have
been altered and deleted over time, or on disk files and hard disks that have
become fragmented.
Rename
An operating system function to alter the name of an existing file or
directory.
Reply
A message sent in response to another.
Report
Processed output in which data has been selected and presented in such a way
as to provide information to a user. It is normally a function of a database.
Report generator
A program or database routine that extracts particular data from one or more
files and manipulates and formats it to a user's requirements.
Representation
The method by which values are stored and manipulated, as in binary
representation.
Reprogrammable
The capability of ROM devices of having bit-patterns erased and rewritten.
Reroute
To switch data flow from one channel or circuit to another because of a
failure in the first.
Reserved
Dedicated to a particular function or use.
Reserved word
A word in a programming language with a meaning that is fixed and cannot be
used in any other context, for example as a variable or user function name.
Reset
To return a program's or circuit's values to their starting conditions. In TOS
versions including and after 1.4 a reset is available from the keyboard by
pressing the [Control], [Alternate] and [Delete] keys together. This
accomplishes the same thing as pressing the reset switch. A cold boot can be
achieved by pressing [Control], [Alternate], [Right Shift] and [Delete]
together. This clears all of the RAM removing any programs that may be causing
trouble.
Reset button
A switch on a functional unit, such as that on the ST-Falcon range, which,
when pressed, cuts the current from the circuit and causes a reset. Use of the
reset button on a computer normally brings about a warm boot or a re-boot.
Resident
A program or data loaded in main storage and accessible to the processor.
Resize icon
The icon in the bottom right corner of a GEM window, used to change its size.
Dragging this icon causes the window outline of the right and bottom sides to
follow the mouse cursor. When the window is the required size the mouse button
is released.
Resolution
The 'fineness' of detail that can be produced in an image on screen or paper.
In raster scan systems it is always limited, but not so in vector scan
systems. This also applies to bitmapped and vector graphics. This term is
frequently and incorrectly used to describe the overall size of a screen in
pixels, whereas its real meaning has to do with the number of dots or pixels
'per unit of area or length', as in the term 75 dpi.
The ST has the following 'resolutions':
320 x 200 x 4 planes (ST low resolution - 16 colours)
640 x 200 x 2 planes (ST medium resolution - 4 colours)
640 x 400 x 1 plane (ST high resolution - 2 colours)
The TT has these in addition:
320 x 480 x 8 planes (TT low resolution - 256 colours)
640 x 480 x 4 planes (TT medium resolution - 16 colours)
1,280 x 960 x 1 plane (TT high resolution - 2 colours)
The Falcon030 has those of the ST and in addition many more. See Falcon video.
Resolution enhancement technology - REt
The method, designed by Hewlett-Packard, of refining the print quality of
characters and sloping lines produced by a laser printer. The size and
placement of individual dots is automatically adjusted to fill in corners and
smooth jagged edges. This gives the appearance of a higher resolution output.
Resource
That which is allocated to a user or program in order to perform processing.
These may be hardware peripherals, storage space and processor time slices.
Resource construction set
The original program from Digital Research and the generic name for programs
that aid the creation and development of GEM resource files. Such programs,
like WERCS, enable the construction of windows, new Desktops and dialogs by
pasting their elements onto the screen. The program then saves these GEM
objects to a .RSC file and constructs a language header file so that these
objects can be referenced by the programmer from within the source code
program.
Resource file
A file with the extender .RSC containing the AES tree data structures for use
by its companion GEM program. These resources are the menus, dialog boxes,
icons, images, alert boxes and strings that form the graphic interface of GEM
programs and are called upon, drawn and manipulated by the resource file's
program which has the file name extender .PRG or .APP.
Response
A reply or action following a request or receipt of a message.
Response time
The time taken to receive output from a computer after a user's input,
normally the time taken from pressing the [Return] key to receiving the first
output character from the computer.
Restricted
Files, data or storage locations that are unavailable for use without
authorization.
Result
The product or output of an operation.
Results
The printed or displayed output that is produced by a user program.
REt
Resolution Enhancement Technology.
Retrace time
In a CRT, the time required for the electron beam to move to a position to
start a new scan. The time taken to move from the left-hand edge of the screen
to the right-hand edge on the next line is the horizontal retrace time or fly-
back time. The time taken to move from the bottom right-hand edge of the last
scan line to the left-hand end of the top scan line is the vertical retrace
time. It is in these intervals that a computer can perform certain interrupt
operations, although on the ST-Falcon range the vertical retrace time is the
most useful. These interrupt routines are called Vertical Blank interrupts.
See HBL and VBL.
Retrieval
The operation of locating and obtaining a particular item from storage.
Return address
An address in a calling routine to which a called routine will return control
when complete.
Return key
See Carriage return.
Reverse Polish notation
See Polish notation.
Revision
The process of making corrections and updates to software and documents.
Revision level
A number indicating the status of a program or document with respect to
changes and developments. Sometimes synonymous with version number.
RF
Radio Frequency.
RFI
Radio Frequency Interference.
RGB
Red Green Blue. A term used to describe types of computer monitors which have
three electron guns, one for each colour. The simplest system provides just
eight colours as each gun can be on or off (counting black - all guns off - as
a colour). A development on this is the RGBI method ('I' standing for
intensity) where the brightness of each gun can be controlled to half its
normal level doubling the colour range. See Analogue monitors.
RGB
Red Green Blue. The colour signals that the ST-Falcon range computer produces
to create its colour display. The combinations of the different intensities of
the red, green and blue colour guns in the monitor create the colour palette
of the computer. For the ST and Mega ST there are eight different intensities
for each colour giving 512 colours. For the STE, Mega STE and TT each colour
has sixteen different intensities available giving 4,096 different
combinations. On the Falcon, each colour has up to 64 different intensities
giving a palette of 262,144 different colours.
RGBI
Red, Green, Blue, Intensity. See RGB.
RI
Ring Indicator.
Ribbon
A spoolable ink-impregnated fabric or carbon-coated film used to form
characters by typewriters and impact printers by being struck against paper.
Ribbon cable
A flat, plastic multi-conductor cable in which the conductors lie parallel to
each other, being insulated and supported by the plastic. The connections are
easy to make using an insulation displacement method.
Right justify
In print preparation or word processing, where the text is blocked and aligned
with the right-hand margin only. It is sometimes confused with 'full
justification'.
Right shift
A movement of the contents of a storage location or register to the right in
increments. With numeric data it has the effect of dividing the value by the
radix or base which is usually two in computers, the radix of binary numbers.
Rigid disk
A hard disk.
Ring indicator
A signal from automatic answering equipment, such as a modem in answer mode,
to a computer indicating that it has detected an incoming call.
RISC
Reduced Instruction Set Computer or Reduced Instruction Set Chip. A type of
processor that supports a small set of instructions optimized for speed making
the chip perform very quickly when compared to CISC processors. Normally, at
least one instruction is performed for each system clock 'tick' whereas most
MC68000 instructions are in the range of 4-36 clock cycles. Complex
instructions can be built up from these simpler ones when required. The Acorn
Archimedes uses a RISC chip called ARM.
Riser
That part of a lower-case character that extends above the height of a lower-
case 'm' or half-line, such as in an 'h' or 'b'. Synonymous with ascender.
RLE
Run Length Encoding. One of the first lossless file compression methods, also
one of the easiest to implement and usually providing efficient compression of
image files in particular (except true-colour images). The GEM .IMG, .TIF and
.PCX file formats use RLE compression. The RLE algorithm looks for repeated
groups of data, bit patterns or bytes, and stores them only once keeping a
count how many times the pattern is found.
Rollover
The action of pressing two or more keys simultaneously or nearly so, on a
keyboard. Because of fast typing techniques and multiple key commands, a
keyboard processor must be able to detect all these key presses and not ignore
any.
ROM
Read-Only Memory. Memory that can be read repeatedly but cannot be written to,
being non-volatile. Usually, semiconductor memory that has been programmed as
a step in its manufacture to perform some task. The TOS operating system is
stored in ROMs for fast boot-up of the system when switched on. The
alternative, as in many other systems, is to have the operating system on disk
which can result in the slower operation of the computer, a slower boot up,
some functions being awkward with only one floppy disk drive and less user
memory available. However, with cheap hard disks and lower RAM prices, these
disadvantages increasingly cease to become a hindrance. The main criticism of
the operating system being on ROM is that updating it is expensive and
requires the installation of new ROMs which isn't always possible. This is
evident with the introduction of the TOS 2 and TOS 3 ROMs which are impossible
to fit to TOS 1 computers without some considerable effort and expense.
Root
In a hierarchical data structure, such as a disk filing system, it is the
owner on the highest level, which is that entity that must be accessed first
in order to access other elements of the structure. For instance, in any disk
drive the root is the name of the disk drive, i.e. in the path name
C:\PROTEXT\DOCS\JANE.DOC the root directory is C:\.
Root directory
The first directory encountered when a disk drive is opened. It is the
directory outside all other directories or folders and is specified by the
disk identifier followed by a backslash. See Root.
Rotate
To turn a graphics image about an axis.
ROTFL
Rolling On The Floor Laughing. Commonly used shorthand in e-mail and other
messages.
Round
To reduce the number of digit positions by which a number is represented by
eliminating its least-significant digits.
Round down
To drop one or more digits in least-significant positions, e.g. 67.42, 67.45
and 67.48 become 67.4.
Round off
To drop one or more digits in least-significant positions and to adjust the
least-significant of the remaining digits so that the value is closest to that
of the dropped ones, e.g. 67.42, 67.45 and 67.48 become 67.4, 67.5 and 67.5
respectively.
Round up
To drop one or more least-significant digits and to add a value of one to the
least-significant remaining digit, e.g. 67.42, 67.45 and 67.48 all become
67.5.
Rounding error
The error introduced by rounding a number which subsequently loses its
accuracy, i.e. when rounding 67.42 to 67.4 a rounding error of .02 was
introduced in that value.
Route
A path or means for moving data from one location to another sometimes via
intermediate locations. The term normally applies to data communications
transfers.
Router
Dedicated computers that connect two networks using the same protocols
together such as, an Ethernet and one connected via a leased line. The router
transfers the packets of data along the quickest path through various systems,
each packet perhaps taking a different route depending on system loads.
Routine
A sequence of instructions that can be independently loaded or called to
perform some operation, sometimes synonymous with subprogram.
RS-232C
The EIA standard for serial data interfaces for connections up to 50 feet and
for bit-serial data transmission at up to 19,200 bits per second. The
connection is between a DTE (Data Terminal Equipment, usually the computer)
and a DCE (Data Communication Equipment, usually the peripheral). The
specification allows for synchronous and asynchronous communication where the
character length and bit codes may vary according to a particular application.
Primary and secondary channels, handshaking and timing signal are catered for
allowing versatility of configuration, including transmit only, receive only,
half-duplex and full-duplex. The 0-bit is represented by a positive pulse
between 3 V and 25 V and a 1-bit by a negative pulse in the same range. The
standard connector is a 25-pin D plug and socket type although many
manufacturers use a 9-pin D type plug and socket to save space. This standard
was adopted by the CCITT in their V.24 and V.28 Recommendations. The serial
ports on the ST, TT and Falcon are not fully wired to this standard, only
those most commonly used signals are utilized, hence the use of 9-pin
connectors on the TT and Falcon.
Table R1: RS-232C Pin Functions
Pin Abbreviation To Meaning/Function
1 FG Frame ground
2 TXD DCE Transmitted data
3 RXD DTE Received data
4 RTS DCE Request to send
5 CTS DTE Clear to send
6 DSR DTE Data set ready
7 SG Signal ground
8 DCD DTE Data carrier detect
9 DTE Positive DC test voltage
10 DTE Negative DC test voltage
11 QM DTE Equalizer mode
12 SDCD DTE Secondary data carrier detect
13 SCTS DTE Secondary clear to send
14 STXD DCE Secondary transmitted data
15 TC DTE Transmitter clock
16 SRXD DTE Secondary received data
17 RC DTE Receiver clock
18 DCR DTE Divided clock receiver
19 SRTS DCE Secondary request to send
20 DTR DCE Data terminal ready
21 SQ DTE Signal quality detect
22 RI DTE Ring indicator
23 DCE Data rate selector
24 TC DCE External transmitter clock
25 DCE Busy
RS-232 serial port
A serial port normally conforms to the RS-232C standard or more usually a
subset of the standard, which causes much confusion when connecting devices. A
serial port sends data serially, that is, one bit after another and this
limits its speed when compared to a parallel port or the SCSI or DMA ports.
The ST ports operate between 50 and 19,200 bps as do the two MFP 68901 serial
ports on the TT, each of which has a separate MFP chip. The two SCC serial
ports on the Mega STE, TT and Falcon can manage 115,200 bps on Port A or
153,600 bps on Port B but the XBIOS does not support such speeds. On the ST
and STE, the MFP 68901 provides the transmit (MFP Serial Output - pin 2) and
receive (MFP Serial Input - pin 3) data lines and also handles the CTS (MFP
Interrupt Input I2 - pin 5), DCD (MFP Interrupt Input I1 - pin 8) and Ring
Indicator (MFP Interrupt Input I6 - pin 22) lines as interrupts. The YM-2149
sound chip provides the RTS signal (PSG I/O port A bit 3 - pin 4) and the DTR
line (PSG I/O port A bit 4 - pin 20) which together with a Chassis Ground (pin
1) and a Signal Ground (pin 7) completes the port connections. It is evident
that only nine of the RS-232C 25 pins are used and connected by Atari
computers (and indeed, most other computers) although a full 25-pin connector
is provided on the ST and STE computers, whilst the TT, Mega STE and Falcon
use 9-pin sockets. See RS-232C, SCC ports.
RSC
The file name extender for a GEM program's resource file.
RSN
Real Soon Now. Commonly used shorthand in e-mail and other messages.
RTC
Real-Time Clock.
RTFM
Read The Flipping Manual. The original version (attributed to a popular High
Street electrical store salesman) is unprintable but doesn't require much
imagination! Commonly used shorthand in e-mail and other messages.
RTS
Ready To Send. An interface signal from a terminal to a modem indicating that
it has data to send.
Rubber banding
On a graphical screen, the movement of a common vertex of a set of lines
without moving their other ends. This is commonly seen when dragging the
window re-size icon when the right-hand and bottom sides of the window
rectangle are moved but not the other two edges, thus stretching the 'box' as
if made of rubber bands. In a Desktop directory window, more than one file
icon can be selected by pressing the left mouse button and dragging downwards
which reveals an outline of a box to encompass the selected files which become
inverted when the mouse button is released.
Ruler
A device in word processing and DTP programs to aid the positioning and
alignment of text. It is commonly marked in tenths of inches, centimetres and
millimetres, picas or points. Tab alignment indicators are usually inserted
within it as well as the positions of the left- and right-hand margins.
Run
To execute a program or batch file.
Rx (RX, RxD, RXD)
Shorthand for receive or receiver.
R
130 entries
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