"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 ***************************************************************************** E EAROM Electrically Alterable Read-Only Memory. A ROM chip whose contents can normally be read and are not volatile, but may be altered by electrical signals. EBCDIC Extended Binary Coded Decimal Interchange Code. An 8-bit internal storage code used by IBM mainframe computers to represent a character set. Echo In a communications link, the characters typed on a transmitting computer are reflected back from the receiving computer before being displayed on the screen. Also, synonymous with conference. EchoMail Public messages in an echo or conference of a telecommunications network, usually a bulletin board system. ECL Emitter Coupled Logic. Extremely fast logic chips not normally common on microcomputers being difficult to use. The high resolution monochrome circuitry on the TT is implemented in ECL which gives a very good quality and fast display. However, it does require a special monitor, such as the Atari TTM194. ED Extra Density. Term applied to the 3.5 inch floppy disks with a capacity of 2.88 Mb. Edge connector An etched connector along a free edge of a circuit board for connection to another circuit board, like that on a cartridge. Edit The act of examining displayed data and correcting and modifying it before being processed, stored or printed. Edit menu Usually the third GEM program menu with such items as "Undo", "Cut", "Copy", "Paste" and "Delete". Editable text field A line in a GEM dialog box where input text can be typed and edited by the user. The [Tab] key will move the cursor (usually a thin vertical line) from one field to another. Editor A program that allows data to be edited. The term commonly refers to a text processor producing ASCII unformatted text. EEPLD Electrically Erasable Programmable Logic Device. A complex logic chip that can be erased and programmed by applying a voltage to certain pins. It has the advantage of being programmable on the circuit without having to be removed. EEPROM Electrically Erasable Programmable Read-Only Memory. Another name for an EEROM. EEROM Electrically Erasable Read-Only Memory. A read-only memory that can be erased and programmed by applying a voltage to certain pins to write 1-bits where required. Erasure is by reversing the polarity used in writing. EFTS Electronic Funds Transfer System. A data network system for making direct debits and credits between banks without the movement of paper. EFTPOS Electronic Funds Transfer at Point Of Sale. A system for directly debiting and crediting a customer's bank account at the place of purchase. EGA Enhanced Graphics Adaptor. An IBM PC graphics system introduced to improve on the CGA standard, having 16 colours at 320 x 200, 640 x 200 or 640 x 350 resolutions. It is now largely replaced by the VGA standard. EIA Electronic Industries Association. A US standards organization responsible for the RS-232C serial communication specifications. EISA Enhanced Industry Standard Architecture or Extended Industry Standard Architecture. An expansion slot connection used on IBM PC compatible computers which can accommodate up to 32-bit data transfers. The standard was introduced by a group of manufacturers in response to IBM's MCA slot system which was subject to royalties. EL ElectroLuminescent. Electroluminescent displays produce light by placing an alternating voltage between phosphors. They have better contrast than LCD displays, are reliable and use less power than a CRT screen and are available up to 640 x 480 resolution. They are normally monochrome (amber yellow) although full colour displays have been developed. See Electroluminescence. Electrode The stylus in a thermal matrix printer. Also, a conductor that passes current between two different conducting mediums. Electroluminescence The term applied to the 'cool' conversion of electricity into light, such as by the phosphor on a cathode ray tube or by a light-emitting diode. Electromechanical A device that uses electricity to move or rotate elements, such as a disk drive or a motor. Electronic A term applied to devices and circuits in which transistors and other semiconductor devices or valves are used to control electric currents. Electronic mail See E-mail. Electrosensitive matrix printer A printer that uses electrically conducting styli to selectively burn away a silver coating on black paper to produce dot matrix characters. Printing quality is extremely poor and slow, but such printers can be made very small for use with portable or hand-held computers and calculators. Element A component of a larger system or unit. Also, an item of an electronic circuit. Ellipsis A string of three full stops. In a GEM program menu, any menu items followed by an ellipsis, such as "Load...", indicates that additional action or input will be required from the user to carry out the desired task. This may mean the use of another popup menu or a dialog box. E-mail Electronic Mail. The system of sending personal messages transmitted between participant's computers or FAX machines rather than by the postal system (referred to as 'snail-mail'). E-mail is a private message directly addressed to a recipient. Embedded Included in something else, for instance in word processing, non-printable printer control codes inserted within the text. Embedded SCSI drive A hard disk drive mechanism with a SCSI interface built in. These are compact units which are popular as Atari computer storage devices, except that the Falcon has an internal IDE interface which will not accept them. EMI ElectroMagnetic Interference. Every electric current produces a magnetic field around the wire or circuit through which it flows. If the current increases or decreases so does the magnetic field. If this field passes through a wire, a voltage signal can be induced in that wire which can interfere with its correct signals and the operation of that circuit. If electric currents are changing very rapidly, radio signals can be generated which may cause interference with other equipment. Emoticon EMOTion ICON. See Smiley. Emulation Using programs, and maybe hardware, to execute programs designed for one computer on another, such as running PC programs on the ST. The ST is capable of emulating many different types of computers either through software alone or with the aid of some hardware including the necessary processors or system ROMs. Emulator A program or hardware that enables one computer to emulate another. Also, a program or hardware that is used to replace a missing facility, for instance, the VT52 software emulator in TOS which can make the ST behave as a VT52 terminal. The ST can, with the aid of software and hardware, emulate many different types of computer, some very successfully, especially the Apple Macintosh with the Spectre. IBM PC emulation is available, Sinclair Spectrum, ZX81 and QL, Acorn BBC and Atari XL. Other operating systems, such as CP/M, UNIX (through the MINIX or LINUX projects or the ASV kit on a TT), OS/9, SMS2 and OMEn can also be run on the ST-Falcon although this really isn't emulation. Enable To take some action that makes another take place. To make a facility or function operable. Encode To change the form of data in accordance with a set of rules. Encryption To convert normal file data into an unreadable form based on a key usually for security purposes. End of file - EOF A character, frequently [Cntl-Z] ASCII code 26, used to designate the end of data in a file. Engine A term sometimes applied to the core functional part of hardware or a program. Enhance To improve the capability of a system by adding hardware or software or replacing current items with updated versions. Also, to improve the appearance of an image to show more detail. Enlarge To increase size. ENQ ENQuiry. A transmission control character used to request a response from the receiving station or to ask for identification. Enter Typing in commands or data at a system prompt and pressing the [Return] or [Enter] key to place that data in memory enabling its processing by the program. Enter key Synonymous with the [Return] key and generally returning the same code, ASCII character 13. Entity A general term for anything that is known to an operating system. Entry point An instruction address or label of a place in a program where execution can begin, e.g. to test a particular function. Often used in assemblers. Envelope The included frequencies of a signal, those that are represented in a transmitted or received signal. Environment The resources available for a program's execution within the computer system. Operating system variables can be defined pointing to various locations in memory or disk where these resources are stored, the most common being the PATH= environmental variable which is the search path used to locate program resources and files, e.g. PATH=;C:\;C:\FONTS;D:\;E:\LC5\C. EPLD Erasable Programmable Logic Device. A complex logic chip that can be programmed by the user by applying voltage to certain pins. It has the advantage of being programmable on the circuit without its removal but can only be erased by exposing the chip through the 'window' on the top of the chip to high-intensity ultraviolet light like EPROMs. EPROM Electrically Programmable Read-Only Memory or Erasable Programmable Read-Only Memory. A read-only memory that can be programmed by applying a voltage to selected pins and is usually erased by exposing the chip through the 'window' on the top of the chip to high-intensity ultraviolet light. EPS Encapsulated PostScript. A graphics file format produced by PostScript compatible programs which is written in the PostScript language and contains information that allows images to be displayed with the correct scale and at the correct position. Such files can be imported into some DTP programs and output to PostScript printers. Epson A printer manufacturer whose dot matrix printer control codes have generally become a standard for operating dot matrix printers. Erase To remove data from storage. On a disk the first byte of the file name in the directory is overwritten with ASCII code 229 'å' and the FAT is modified to show the sectors occupied by that program as being free. However, the file's data is still physically intact and recoverable as long as the disk is not written to. Erase head The head in a magnetic tape unit that erases previously recorded data from the tape before new data is written. In magnetic disk recording, they perform track trimming. Error An unwanted and unintended result, such as a failure to pass a validity test during a program's compilation. Also, where the received data is not the same as that transmitted or where the data read from a storage location is not the same as that written there. Error correction A method of providing a means of detecting errors in received data and once found, requesting the retransmission of those bits or, in more sophisticated systems, correcting them according to some established algorithm. Error detection See Error correction. Error message A displayed message indicating an error of some kind. See BIOS errors, GEMDOS errors. Esc ESCape. The Escape character, ASCII character 27. Escape A transmission control character, ASCII code 27, used to indicate that certain following characters are control codes and not normal text. Used by peripherals, such as printers and screen displays to control how the text is displayed (bold type, different font type etc.). Escape key A key performing a function designated by the controlling program. It can send the ASCII Escape character in some situations, such as with communications terminal software. In the GEM Desktop it forces the re-reading of the top disk directory window in order to recognize a possible disk change. In most GEM programs it is used to clear an editable field of text, such as a .TTP program command line. ESDI Enhanced Small Device Interface. An interface system for connecting hard disk drives and optical disks to computers. It was introduced in the mid-1980s to produce a greater data rate than the ST506 interface and was generally found on the IBM PC compatible computers. It is now largely replaced by IDE and SCSI interfaces. ESVGA Extended Super Video Graphic Adaptor. A screen graphics standard found on some high-end IBM PC compatible computers providing an improved VGA display of 1,024 x 768 in sixteen or 256 colours. Etch To selectively remove metal in producing a printed circuit board. Ethernet A local-area network developed by Intel, Xerox and Digital Equipment using coaxial cable and operating at ten megabits per second. It can support several hundred terminals and is relatively cheap to install. The Mega STE and TT has the capability of connecting to Ethernet networks belonging to other system by installing a VME bus-based or SCSI-based Ethernet controller card. Evaluate To reduce an expression to its simplest form, to solve it. Even parity See Parity. Event An external condition of significance to an operating system or executing program. Also, a GEM generated signal to a program that an external action has occurred, such as a mouse click or window closure, that has to be acted upon by the program. Event driven Interrupt driven. EVGA Enhanced Video Graphics Adaptor. Sometimes called Super VGA (SVGA). A screen graphics standard providing an improved VGA display of 800 x 600 with sixteen or 256 colours found on IBM PC compatibles. Exception A condition encountered during program execution that causes an immediate transfer of control to an exception routine that can deal with that condition. They normally occur when the processor has been given an instruction that it cannot perform, such as a bus error, address errors, illegal instructions, divide by zero etc. Besides coming from the processor, exceptions can also come from external devices such as peripherals, for instance when a printer goes off-line whilst printing. Synonymous with the term 'interrupt'. See Exception vectors. Exception routine A routine to which control is passed in order to deal with some abnormal condition that occurs during processing. Exception vectors On the ST-Falcon range, the first 1,024 bytes of memory are reserved by the processor for the exception vectors. Routines (in ROM or provided by the user) that use exception handling store the addresses they require in this range of memory. If an interrupt error occurs the processor will stop execution of the program, save the program counter and status register on the stack and branch to a routine, the address of which is stored in the interrupt's exception vector. If a bus error occurs, for instance, the address of the routine to pass control to is stored at location $008. As many bombs appear on the screen as the interrupt vector number, two for a bus error. Execution then returns to the Desktop, but this may not be possible depending on how much memory was corrupted. Table E1: Exception Vectors Contents Vector Address Meaning TOS 1.4 Number in hex example 0 $000 Stack pointer after reset: $602E0104 1 $004 Program counter after reset: $ FC0030 MC680x0 Exception Vectors: 2 $008 Bus error: $ 2FC0B0A 3 $00C Address error: $ 3FC0B0A 4 $010 Illegal instruction: $ 4FC0B0A 5 $014 Division by zero: $ FC07A0 6 $018 CHK instruction: $ 6FC0B0A 7 $01C TRAPV instruction: $ 7FC0B0A 8 $020 Privilege violation: $ 8FC0B0A 9 $024 Trace: $ 9FC0B0A 10 $028 Line-A emulator: $ FCAB3C 11 $02C Line-F emulator: $ 53AFC 12 $030 reserved: $ CFC0B0A 13 $034 FPU protocol violation (TT/Falcon): $ DFC0B0A 14 $038 Format error (TT/Falcon): $ EFC0B0A 15 $03C Uninitialized interrupt: $ FFC0B0A 16 $040 reserved: $10FC0B0A 17 $044 reserved: $11FC0B0A 18 $048 reserved: $12FC0B0A 19 $04C reserved: $13FC0B0A 20 $050 reserved: $14FC0B0A 21 $054 reserved: $15FC0B0A 22 $058 reserved: $16FC0B0A 23 $05C reserved: $17FC0B0A 24 $060 Spurious interrupt: $18FC0B0A Auto-Vector Interrupts: 25 $064 Level 1 interrupt (IPL1): $ FC07A0 26 $068 Level 2 interrupt (HBL): $ FC06AA 27 $06C Level 3 interrupt (IPL3): $ FC07A0 28 $070 Level 4 interrupt (VBL): $ FC06C0 29 $074 Level 5 interrupt (IPL5): $ FC07A0 30 $078 Level 6 interrupt (MFP): $ FC07A0 31 $07C Level 7 interrupt (IPL7): $ FC07A0 The TRAP Exception Vectors: 32 $080 TRAP #0 instruction: $20FC0B0A 33 $084 TRAP #1 (GEMDOS) instruction: $ FC92D8 34 $088 TRAP #2 (AES/VDI) instruction: $ FDD40A 35 $08C TRAP #3 instruction: $23FC0B0A 36 $090 TRAP #4 instruction: $24FC0B0A 37 $094 TRAP #5 instruction: $25FC0B0A 38 $098 TRAP #6 instruction: $26FC0B0A 39 $09C TRAP #7 instruction: $27FC0B0A 40 $0A0 TRAP #8 instruction: $28FC0B0A 41 $0A4 TRAP #9 instruction: $29FC0B0A 42 $0A8 TRAP #10 instruction: $2AFC0B0A 43 $0AC TRAP #11 instruction: $2BFC0B0A 44 $0B0 TRAP #12 instruction: $2CFC0B0A 45 $0B4 TRAP #13 (BIOS) instruction: $ FC07CA 46 $0B8 TRAP #14 (XBIOS) instruction: $ FC07C4 47 $0BC TRAP #15 instruction: $2FFC0B0A The MC68881 FPU Exception Vectors: 48 $0C0 FPU branch/set on unordered condition: $3007779A 49 $0C4 FPU inexact result: $3107779A 50 $0C8 FPU floating-point divide by zero: $3207779A 51 $0CC FPU underflow: $3307779A 52 $0D0 FPU operand error: $3407779A 53 $0D4 FPU overflow: $3507779A 54 $0D8 FPU signalling NAN: $3607779A 55 $0DC unassigned: $3707779A The MC68851 MMU Exception Vectors: 56 $0E0 MMU configuration error: $3807779A 57 $0E4 MMU illegal operation: $3907779A 58 $0E8 MMU access violation: $3A07779A 59- $0EC- 63 $0FC reserved: The MC68901 MFP Vectors: 64 $100 Parallel port busy *: $40B03B04 65 $104 RS-232 data carrier detect *: $35582FAC 66 $108 RS-232 clear to send: $ FC38AA 67 $10C BitBLT complete *: $1EA818FC 68 $110 RS-232 baud rate generator/Timer D *: $13500DA4 69 $114 200 Hz system clock/Timer C: $ FC4242 70 $118 Keyboard and MIDI ACIAs: $ FC3AEC 71 $11C Floppy controller and DMA *: $F148EB9C 72 $120 HBlank counter/Timer B **: $E5F0E044 73 $124 RS-232 transmit error: $ FC3918 74 $128 RS-232 transmit buffer empty: $ FC3890 75 $12C RS-232 receive error: $ FC38F6 76 $130 RS-232 receive buffer full: $ FC37F2 77 $134 DMA sound counter/Timer A: $AD38A78C 78 $138 RS-232 ring indicator *: $A1E09C34 79 $13C Mono detect/DMA sound complete*: $968890DC * = Normally disabled ** = Initially disabled by the operating system Interrupt 65 $104 on a Falcon is connected to the parallel port Acknowledge signal and not the serial port. Interrupt 78 $138 is the only serial port vector that remains part of the MFP chip on the Falcon, all other functions being transferred to the SCC chip. The TT MC68901 MFP Vectors (TT only): 80 $140 General purpose I/O pin: $8B308584 81 $144 General purpose I/O pin: $7FD87A2C 82 $148 SCC DMAC interrupt: $74806ED4 83 $14C RS-232 ring indicator: $6928637C 84 $150 RS-232 baud rate generator (Timer D): $5DD05824 85 $154 SCC TxCB (Timer C): $52784CCC 86 $158 reserved: $47204174 87 $15C SCSI DMAC interrupt: $3BC8361C 88 $160 unassigned (Timer B): $30702AC4 89 $164 RS-232 transmit error: $25181F6C 90 $168 RS-232 transmit buffer empty: $19C01414 91 $16C RS-232 receive error: $ E6808BC 92 $170 RS-232 receive buffer full: $ 310FD64 93 $174 reserved (Timer A): $F7B8F20C 94 $178 RTC IRQ: $EC60E6B4 95 $17C SCSI controller IRQ: $E108DB5C The Zilog 86C30 SCC Vectors (Mega STE, TT, Falcon only): 96 $180 SCC port B transmit buffer empty: $D5B0D004 97 $184 unused: $CA58C4AC 98 $188 SCC port B external status change: $BF00B954 99 $18C unused: $B3A8ADFC 100 $190 SCC port B receive character available: $A850A2A4 101 $194 unused: $9CF8974C 102 $198 SCC port B special receive condition: $91A08BF4 103 $19C unused: $8648809C 104 $1A0 SCC port A transmit buffer empty: $7AF07544 105 $1A4 unused: $6F9869EC 106 $1A8 SCC port A external status change: $64405E94 107 $1AC unused: $58E8533C 108 $1B0 SCC port A receive character available: $4D9047E4 109 $1B4 unused: $42383C8C 110 $1B8 SCC port A special receive condition: $36E03134 111 $1BC unused: $2B8825DC 112- $1C0- 255 $37F undefined: The vector for division by zero points to a RTE instruction and returns directly to the interrupted program. Most vectors in an empty computer point to the same routine, $00FC0B0A in TOS 1.4 for instance. In 24-bit addressing systems (i.e. those with a MC68000), the number preceding this address in the last column above is the hexadecimal version of the vector number and indicates how many bombs are shown on the screen if that exception vector is called when an error occurs. The most important exceptions are Bus errors, Address errors, Illegal instructions, Zero divide, CHK instruction, TRAPV instruction, Privilege violation, Trace error, Spurious interrupt. See separate entries for an explanation of these. Exchange To transpose or to replace one thing with another. Executable A program file capable of having its instructions executed. Executable file A program file, one with a .PRG, .APP, .TOS, .TTP, .ACC or .GTP extender. Executable file header See Program header. Execution Performing the operations specified in the instructions contained within a program. Executive A group of programs or routines belonging to an operating system that control the execution of other programs. Exist To be present in main storage. Exit The place in a program where execution stops normally and cleanly. Expansion board A printed circuit board that provides for additional hardware facilities, such as extra ports. Expansion bus The Mega ST was the first of the ST-Falcon range to be fitted with an expansion bus connector, internally fitted on the motherboard. It is an extension of the MC68000 processor bus to a 64-pin (two rows of 32) male socket; the pins being almost a direct image of the 68000 pins connected straight to these lines without any buffering. This means that only one LS TTL load is allowed. Power for any device on the port can be obtained from a spare power connector on the motherboard or from the socket itself. Expansion cards may be half-depth or full length. Full length cards can extend to the rear of the computer where a removable panel can allow for external connectors. Any memory on the expansion bus must exist between $00C00000 to $00CFFFFF. This port is commonly used for graphics cards, such as the Reflex card; coprocessors, such as the SFP004 FPU card; and emulators, such as AT Speed PC emulator. The TT and Mega STE have, instead of a 68000 expansion bus, a VME internal expansion connector. See VME bus. The Falcon has two internal expansion buses which consists of two male sockets each, one 30-pin (two rows of fifteen) and the other 50-pin (two rows of 25). The processor direct slot is designed to be used for third party expansion boards, such as for IBM PC 386 emulation and JPEG and MPEG video boards. The smaller connector carries the sixteen data lines (upper sixteen bits of the 68030 data bus D16-D31) and the 23 address lines (lower 23 bits of the 68030 address bus) are carried on the other larger connector. 16 MHz and 500 kHz clock signals are provided. This expansion bus essentially includes a 68000 direct microprocessor interface with some of the signals being synthesized from the 68030 equivalents. As with the Mega ST port, no signal should ever be connected to more than one equivalent TTL load. The other expansion connector is for the custom RAM expansion board and has 32 data lines and 24 address lines. The presence of one board is required. Upgrading the RAM on the Falcon means that the old board is taken out and the new one inserted. The Falcon also has an internal IDE connector consisting of a 44-pin male socket for a 2.5 inch IDE hard disk drive. See the Connectors Appendix C. Expert system An interactive database of a particular speciality (medicine, geology) which, when accessed and queried, gives output similar to that given by a 'real' human expert. Exponent A number or symbol written to the upper right of another to indicate its power, such as 2^3 meaning 2 x 2 x 2. Export To save data in a program in a form which is intended to be read by another program, such as exporting an image of a bar graph from a spreadsheet program to load into a report being written in a DTP program. Expression Representation of a mathematical or logical condition, such as a = b + c. EXTEND.SYS A file necessary for the operation of FONTGDOS and FSMGDOS. It provides the means of communication between the user and FSMGDOS containing details of the caches' sizes and the point sizes of the scalable outline fonts. BITCACHE is the cache size used for storing the bitmapped fonts and should be set to a little larger than the biggest font file to be used. FSMCACHE has two parameters: the first is the cache for the scalable outline fonts and the third cache is used for internal buffers and data structures and its size depends on how many fonts are used and their point sizes. EXTEND.SYS details are normally altered by use of the FSM.ACC or FSM.CPX accessories. See FSMGDOS, FONTGDOS. Extender In MS-DOS and GEMDOS, the optional last three characters of a file name by convention describing its type, such a .PRG or .ACC. External call A call to a routine not compiled with the program in which it is called, such as a routine contained in the operating system. External interrupt An interrupt that is not caused by an event in the routine that is interrupted. External modem A free-standing modem not installed within the computer it serves. External storage Backing storage, storage that is neither main storage (RAM) or within the CPU. It usually refers to disks, tape etc. devices attached to the computer even if within the same casing. Extract To select those items of data that conform to certain criteria and remove to another storage location. E 95 entries EOF