"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 EOF