#computer terms

I don't know anything about computer or mechanical engineering (it's very funny to me that I am in the Transformers fandom and I don't even care about cars), but I do care about improving my writing. I have gathered a list of terms that sound very sciencey and applicable to mechs, some from Martha Wells's "Murderbot Diaries," some from fanfiction/fandom (shout-out to the Crime in Crystals series by Aard_Rinn and Baebeyza, they wrote Transformers better than any Transformers comic/TV show did), and a lot from just surfing through Google and going, "well, what the hell is this? Okay, but what the hell is THAT?".

Also, as I was writing this post, I ended up getting sucked into this article:

And this really bloated my already long list of terms. Very easy to read if you want to glance it over yourself.

It's not an exhaustive list and who knows if it will be useful to you - but maybe you can reblog with your own add-ons of terms and definitions you think make a Transformers fan work just that much better.

The list is below the cut:

100% CPU Load - CPU is fully occupied with too many processors/applications/drivers/operations - not necessarily synonymous with an overload.

Actuators* - A device that causes a machine or other device to operate (Ex: a computerized unit instructs the actuator how to move the tires on a vehicle); create linear and rotary movement (Ex: A hydraulic actuator on a valve will move that valve in response to a sensor/signal); Linear actuators "move a piston back and forth inside a cylinder to build pressure and 'actuate', or complete an action".

* Think of actuators as devices that help produce linear motion and motors as devices that help produce rotational movement. Hence, some consider actuators as a type of motor. But a motor is not a type of actuator (jhfoster.com).

Alternator - Converts mechanical energy to electrical energy with an alternating current. The stator and rotor inside the alternator work as magnets and rotate to generate the alternating current. Then the alternating current (AC) is transformed into a direct current (DC) that charges the battery.

Archive (Archive files) - used to collect multiple data files together into a single file for easier portability and storage, or simply to compress files to use less storage space.

Arithmetic Log Unit (ALU) - the part of a central processing unit that carries out arithmetic and logic operations on the operands in computer instruction words. In some processors, the ALU is divided into two units: an arithmetic unit (AU) and a logic unit (LU).

Augment - Make something greater; increase.

Auxiliary Battery - Designed to run as a backup to the starting battery and provide power to some essential equipment like engine start/stop and other systems that require power while the engine is off to put less strain on the main battery and alternator.

Bandwidth - A measurement indicating the maximum capacity of a wired or wireless communications link to transmit data over a network connection in a given amount of time.

Behavioral Coding - A term used in Martha Wells' Murderbot Diaries; essential, code for behaviors.

Branch Instructions - Use programming elements like if-statements, for-loops, and return-statements; used to interrupt the program execution and switch to a different part of the code.

Branch Predictors - Track the status of previous branches to learn whether or not an upcoming branch is likely to be taken or not.

Buffer - A region of memory used to store data temporarily while it is being moved from one place to another.

Cathodes vs Anodes - Cathodes are the positive electrode while the anode is the negative electrode; electrons flow from the anode to the cathode and this creates the flow of electric charge in a battery or electrochemical cell.

Catastrophic Failure - Complete, sudden and unexpected breakdown in a machine, indicating improper maintenance.

Central Processing Unit (CPU) - Primary component of a computer that acts as its "control center"; complex set of circuitry that runs the machine's operating systems and apps; the brains of the computer. * Components: Instruction Set Architecture (ISA), Control Unit (CU), Datapath, Instruction Cycle, Registers, Combinational Logic, the Arithmetic Logic Unit (ALU), etc...

Clock - Determines how many instructions a CPU can process per second; increasing its frequency through overclocking will make instructions run faster, but will increase power consumption and heat output.

Combustion Chambers - An enclosed space in which combustion takes place, such as an engine; jet engines also have combustion chambers.

Condition Codes - Extra bits kept by a processor that summarize the results of an operation and that affect the execution of later instructions.

Control Bus - Manages the communication between the computer's CPU and its other components.

Control Unit (CU) - Manages the execution of instructions and coordinates data flow within the CPU and between other computer components.

Cybermetal - Element native to Cybertron and Cybertron alone.

Datapath - The path where data flows as it is processed; receives input, processes it, and sends it out to the right place when done processing; datapaths are told how to operate by the CU; depending on instructions, a datapath can route signals to different components, turn on and off different parts of itself, and monitor the state of the CPU.

Diagnostic and Data Repair Sequence - Term used in Martha Wells' Murderbot Diaries; exactly what it sounds like.

Diode - A semiconductor device with two terminals (a cathode and an anode), typically allowing the flow of current in one direction only.

Discrete Circuit vs Integrated Circuit- Single device with a single function (ex: Transistor, diode) vs Devices with multiple functional elements on one chip (ex: Memories, microprocessor IC and Logic IC).

Drivers - A set of files that help software (digital components, such as Microsoft Office) interface/work with hardware (physical components, such as a keyboard); allows an operating system and a device to communicate.

Electromagnetic (EM) Field - A combination of invisible electric and magnetic fields of force; used in fandom by mechs to broadcast emotions to others.

Flags - A value that acts as a signal for a function or process. The value of the flag is used to determine the next step of a program; flags are often binary flags which contain a boolean value (true or false).

Full Authority Digital Engine Control (FADEC) - Consists of an electronic control unit (ECU) and related accessors that control aircraft engine performances.

Gestation Tank - Used in mech pregnancies, you can pry it from my cold, dead hands.

Heads Up Display (HUD) - A part of the user interface that visually conveys information to the player during gameplay.

Heat Spreader - Often used in computer processors to prevent them from overheating during operation; transfers energy as heat from a hotter source to a colder heat sink or heat exchanger.

HUB - A device that connects multiple computers and devices to a local area network (LAN).

Inductive Charging - How I imagine berths work; wireless power transfer (ex: Wireless charger or charging pad used for phones).

Instruction Cycle - Also known as fetch-decode-execute cycle; basic operation performed by a CPU to execute an instruction; consists of several steps, each of which performs a specific function in the execution of the instruction.

Instruction Set Architecture (ISA) - The figurative blueprint for how the CPU operates and how all the internal systems interact with each other (I think of it like a blueprint for the brain).

Irising - Term used in fanfiction (specifically the Crime in Crystals series) to describe the action of the of the spark chamber opening ("The Talk", chapter 6, my absolute favorite chapter out of the entire series). I just really liked how the word sounded in that context.

Life Codes - "For those of us who were forged, Primus, through Vector Sigma, generated a pulse wave. Each one a data-saturated life code faster than thought, brighter than light, racing across Cybertron, sowing sparks..." (~Tyrest/Solomus, Volume 5 of More Than Meets the Eye)

Memory Hierarchy - Represents the relationship between caches, RAM, and main storage; when a CPU receives a memory instruction for a piece of data that it doesn't yet have locally in its registers, it will go down the memory hierarchy until it finds it.

Levels: L1 cache (usually smallest and fastest), L2 cache, L3 cache, RAM, and then main storage (usually biggest and slowest); available space and latency (delay) increase from one level to the next

Depending on the multi-core (a core is usually synonymous with a CPU) system, each core will have its own private L1 cache, share an L2 with one other core, and share an L3 with more or more cores.

Motors* - Any power unit that generates motion; electric motors work by converting electrical energy into mechanical energy... when this happens within a magnetic field, a force is generated which causes shaft rotation.

Multitasking Operating System - Allows users to run multiple programs and tasks almost simultaneously without losing data; manage system resources (such as computer memory and input/output devices), allocate resources, enable multiple users, and eliminate long wait times for program execution.

Network - A set of computers sharing resources located on or provided by network nodes. Computers use common communication protocols over digital interconnections to communicate with each other.

Network Feed - The continuously updating stream of content that users encounter on networking platforms.

Neural Network - A type of machine learning process that uses interconnected nodes (like neurons) to teach computers to process data in a way similar to the human brain; a form of deep learning that can help computers learn from their mistakes and improve their time.

Nimbus - A luminous cloud or a halo surrounding a supernatural being or a saint; has been used in fanfiction synonymously or in junction with the corona of the spark.

Nodes - A connection point between devices that allows data to be sent and received between them.

Oil Sump/Oil Pan - Don't forget to change your mech's oil.

Out-Of-Order Execution - A paradigm used to minimize downtime while waiting for other instructions to finish; allows a CPU to choose the most timely instructions to execute out of an instruction queue.

Overload - Orgasm; an electrical overload occurs when too much electricity passes through a circuit, exceeding its capacity; an information overload is when a system receives more input than it can process, or a state of being overwhelmed by the amount of data presented for processing.

Pedes - Feet

Pipelining - A technique used in computer architecture that allows a processor to execute multiple instructions simultaneously, improving overall performance.

Processing Capacity - The ability and speed of a processor, and how many operations it can carry out in a given amount of time.

Program Counter - A special register in a computer processor that contains the memory address (location) of the next program instruction to be executed.

Programmable Nanobots/Nanites - Cybertronian microbots programmed to do work at the molecular level; used popularly for surface healing and pigment in mechs.

Protected Storage - Provides applications with an interface to store user data that must be kept secure or free from modification; a storage method; a function in mainframe hardware.

Protoform - Formed of an ultra-dense liquid metal and are extremely hard to damage; the most basic Cybertronian form of raw, free-flowing living metal; first stage of Cybertronian life cycle

To create a Cybertronian, you need the protoform, the life-giving spark, and alt-form information.

Register - A type of computer memory built directly into the processor or CPU that is used to store and manipulate data during the execution of instructions.

Ex: "When you run a .exe on Windows... the code for that program is moved into memory and the CPU is told what address the first instruction starts at. The CPU always maintains an internal register that holds the memory location of the next instruction to be executed [the Program Counter]"...

Resource Allocations - The process of identifying and assigning available resources to a task or project to support objectives.

Risk Assessment - Focus on identifying the threats facing your information systems, networks, and data and assessing the potential consequences should these adverse events occur.

Routine - A component of a software application that performs a specific task (ex: Saving a file).

Servomechanism - A powered mechanism producing motion or force at a higher level of energy than the input level (ex: In the brakes and steering of large motor vehicles) especially where feedback is employed to make the control automatic.

Servos - Hands

Shellcode - A small piece of executable code used as a payload, built to exploit vulnerabilities in a system or carry out malicious commands. The name comes from the fact that the shellcode usually starts a command shell which allows the attacker to control the compromised machine.

Semiconductor - A material used in electrical circuits and components that partially conduct electricity.

Semiconductor materials include silicon, germanium, and selenium.

Struts - Bones; A rod or bar forming part of a framework and designed to resist compression.

System/System Unit (in computers) - A setup that consists of both hardware and software components organized to perform complex operations/The core of your computer where all the processing happens.

Task Specific Accelerator - Circuits designed to perform one small task as fast as possible (ex: Encription, media encoding & machine learning).

Teek - Used in Transformers fandom in conjunction with EM Fields; when a mech "teeks" another mech's field, they are feeling the emotions that mech is broadcasting.

Transistor - Enables a computer to follow instructions to calculate, compare and copy data.

Universal Serial Bus (USB) - A standard plug-and-play interface that allows computers and peripheral devices to connect with each other, transfer data, and share a power source; allows data exchange and delivery of power between many types of electronics; plug-and-play interface is also a type of sexual activity used in fandom.

Cause like neither sound 100% correct like

I have two computer mice vs I have two computer mouses

しぼりこむ

① to squeeze, to wring out

② to narrow down, to refine (e.g. filter a search)

入力を続けると、検索結果を絞り込むことができます。

にゅうりょく を つづける と、けんさく けっか を しぼりこむ こと が できます。

If you continue typing, you can narrow down the search results.

Thrashing in computing means too many computer processes compete for inadequate memory resources.

You know those moments where it’s like your entire brain forgets how to work? It’s like everything goes blank even while you struggle desperately to locate even the tiniest thread of thought to get yourself unstuck.

That’s the autistic brain thrashing.

A crash is an application abruptly terminated by the operating system to prevent system instability.

You know that moment where a meltdown or shutdown is about to start and it feels like going past a point of no return? It’s like your entire brain does a bluescreen and reboot to get you unstuck.

A meltdown or shutdown is the autistic brain crashing, and emotional / self control are the programs that terminate.

A20 (Address line 20) The 80286 and higher CPUs allow addresses in real mode to extend slightly beyond the one megabyte mark, which causes an incompatibility with some older programs which expect such addresses to wrap back to the beginning of the address space. For complete compatibility with the 8088, newer machines thus contain circuitry which permits the twenty-first address line (A20) to be disabled. The CPU then effectively has only twenty address lines in real mode, just as the 8088 does, and addresses which would extend beyond the one megabyte mark wrap to the beginning of the address space. See also High Memory Area, Real Mode.

ABIOS (Advanced BIOS) The IBM XT/286 and PS/2 models with 80286 or higher processors contain two separate BIOSes. The ABIOS is a protected-mode BIOS which is used by OS/2. For machines without an ABIOS, such as the IBM AT, OS/2 loads the equivalent of the ABIOS from disk. see also CBIOS

API (Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running. Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes.

APL (A Programming Language) An interactive, mathematically- oriented language which is well-suited to manipulating matrices. Originally using greek letters and numerous special symbols, thus requiring a special display, versions are now available which use keywords in place of the special symbols.

ASCIZ A NUL-terminated ASCII string. The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h. Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL.

AVATAR (Advanced Video Attribute Terminal Assembler and Recreator) A set of control codes which may be used to affect the output of characters to the screen on systems equipped with an appropriate driver. Similar in intent to ANSI sequences, AVATAR has shorter command sequences and provides additional PC-specific functionality. AVATAR is primarily used by the Opus and Maximus bulletin board systems (it was designed by one of the developers of the Opus system).

BASIC (Beginner's All-purpose Symbolic Instruction Code) A programming language originally designed as a means of teaching FORTRAN. There are many variations of BASIC with differing capabilities; the majority are interpreted but compiled BASIC is becoming more popular. All genuine IBM personal computers (including the latest PS/2 models) come equipped with a cassette-based BASIC interpreter in ROM.

BCD (Binary Coded Decimal) A method of data storage where two decimal digits are stored in each byte, one in the upper four bits and the other in the lower four bits. Since only the values 0 through 9 are used in each half of a byte, BCD values can be read as decimal numbers on a hexadecimal display of memory or a file.

Big-Endian One of the two major ways of organizing multi-byte numeric values in memory. A big-endian layout places the most significant byte of the value in the lowest (first) memory location, i.e. 12345678h is stored as 12h 34h 56h 78h. Motorola processors are big-endian. Compare Little-Endian.

BIOS (Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly.

BIOS Parameter Block The BIOS Parameter Block stores the low-level layout of a drive. See also INT 21h Function 53h.

Boot To start up the computer or operating system. The term "boot" is a contraction of "bootstrap", which in turn comes from the expression "to lift oneself by one's boot straps." The ROM BIOS on IBM PCs and compatibles reads in the first sector of the disk, which contains a short (less than 500 bytes) program that reads in a portion of the operating system, which in turn reads in the remainder of the operating system.

Boot Drive The disk drive from which the operating system was booted. See also Boot.

BPB see BIOS Parameter Block

Breakpoint When debugging, a memory location which when accessed causes a break in the normal flow of execution and the invocation of the debugger. Used to let a program run at full speed until a certain instruction is reached or (less frequently) a particular data item is accessed or changed.

Cache Caching is a method of increasing performance by keeping frequently-used data in a location which is more quickly accessed. The most common caches are disk caches (store disk sectors in RAM) and RAM caches (store portions of main memory in special high-speed RAM which may be accessed as fast as the CPU is capable of accessing memory). See also Delayed Write, Write-Through.

Callback A call to a specified function made by the operating system or operating environment when a request (usually an asynchronous request) completes. This permits the calling program to continue operating while the request is processed yet still be aware of its completion immediately without the need to constantly poll the request's status. See also Callout.

Callout A call made by the operating system, operating environment, or an application program on various events, which may be intercepted by other software which is interested in the current state of the system. See also Callback, External Device Interface.

CAS see Communicating Applications Specification

CBIOS (Compatibility BIOS) The IBM XT/286 and PS/2 models with 80286 or higher processors contain two separate BIOSes. The CBIOS is a real-mode BIOS which is compatible with the earlier products in the IBM PC family and PS/2 models with 8086 processors. See also ABIOS.

CDS see Current Directory Structure

CGA (Color/Graphics Adapter) One of the two video display boards introduced together with the original IBM PC. See also HGC, MDA.

Clock Tick 1/18.2 second, or approximately 55 milliseconds. This is the rate at which the IBM PC's system clock is updated.

CMOS (Complementary Metal-Oxide-Silicon) A type of integrated circuit design known for its low power consumption.

CMOS RAM A small amount (typically 64 or 128 bytes) of memory in the system's real-time clock chip that is preserved by the clock's battery and is used for storing configuration information. See also Real-Time Clock.

Communicating Applications Specification DCA and Intel's standard programmatic interface for sending and receiving FAXes via any of a number of internal FAX boards.

CP/M (Control Program for Microcomputers) An early operating system for micros based on the 8-bit Intel 8080 CPU (and later the compatible 8085 and Zilog Z80 CPUs). MSDOS version 1.0 was essentially a clone of CP/M for the Intel 8086.

CP/M-86 One of the three operating systems offered by IBM for its original PC (the other two were MSDOS and the UCSD p-System). It has since evolved into DR-DOS version 6.

CPU (Central Processing Unit) The microprocessor which executes programs on your computer.

Current Directory Structure The data record used by DOS to keep track of the current directory on a drive; whether the drive is valid, network, SUBSTituted, or JOINed; and other pertinent information. See also INT 21h Function 52h.

Cylinder The set of concentric tracks of data located at the same position on each data-bearing surface of the disk. A double-sided floppy will contain two tracks per cylinder.

DAC (Digital-to-Analog Converter) A hardware device (in its simplest form, nothing more than a set of interconnected resistors) which converts a digital number into an analog signal whose voltage is proportional to the value of the digital number. VGA and later color video boards use DACs to convert color values into the analog signals sent to the display; sound boards normally use DACs as well.

DCC (Display Combination Code) A number which indicates both the type of display adapter board and the type of monitor attached to the video board.

Delayed Write A form of caching in which control is returned before the data is actually written to the storage media. See also Cache, Write-Through.

Device Driver An interface module between the device-independent portions of the operating system and an actual hardware device which converts device-independent requests into the actual sequence of device operations to perform the requested action. IO.SYS contains the standard, built-in MSDOS device drivers such as CON, COM1, AUX, PRN, etc. See also INT 21h Function 52h and INT 2Fh Function 0802h.

Device Driver Request Header The data structure passed to a device driver which contains the command to be executed, its parameters, and space for a returned status and data values. See INT 2Fh Function 0802h.

DGIS (Direct Graphics Interface Standard)

Direct Memory Access A method whereby peripherals may transfer data into or out of main memory without the involvement of the CPU.

Disk Transfer Address The Disk Transfer Address indicates where functions which do not take an explicit data address will read or store data. Although the name implies that only disk accesses use this address, other functions use it as well. See INT 21h Function 4Eh for an example of the DTA's use.

DLL see Dynamic Link Library

DMA see Direct Memory Access

DOS Extender A program which allows a program to run in protected mode while still retaining access to real-mode MSDOS services. See also Protected Mode.

DOS Parameter List The DOS Parameter List is used to pass arguments to SHARE and network functions. See also INT 21h Function 5D00h.

DOS Protected-Mode Interface An API which provides basic services for protected-mode programs to allocate memory, invoke real-mode software, etc. See also Virtual Control Program Interface.

DPB see Drive Paramter Block

DPL see DOS Parameter List

DPMI see DOS Protected-Mode Interface

DRAM (Dynamic Random Access Memory) RAM memory which essentially consists of a tiny capacitor for each bit of memory. Since capacitors do not hold a charge indefinitely, DRAM must be constantly refreshed to avoid losing its contents. Also, the process of reading the contents of the memory are destructive, meaning extra time must be spent restoring the contents of memory addresses which are accessed, so DRAM is slower than SRAM. See also Refresh, SRAM.

Drive Parameter Block The DOS Drive Parameter Block stores the description of the media layout for a logical drive, as well as some housekeeping information. See also INT 21h Function 1Fh and INT 21h Function 32h.

DTA see Disk Transfer Address

DWORD Doubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address.

Dynamic Link Library A collection of subroutines which are linked with a program at the time it is loaded into memory rather than permanently placed in the executable. This has the advantage of allowing a single copy of the subroutine library to reside on disk or in memory even when it is used by many programs. It also permits all programs using the DLL to be updated without recompiling simply by installing a new version of the library.

EGA (Enhanced Graphics Adapter) IBM's second color video board for the IBM PC family, capable of a maximum resolution of 640x350 pixels in 16 simultaneous colors of a total of 64 possible colors.

EISA (Enhanced Industry-Standard Architecture) A 32-bit superset of the IBM AT's expansion bus (which is now known as the ISA or Industry-Standard Architecture bus).

EMS see Expanded Memory Specification

EOI (End of Interrupt) A particular command sent to the interrupt controller to indicate that the interrupt has been handled by software and that new interrupts of the same or lower priority may now be signalled by the interrupt controller.

ESDI (Enhanced Small Device Interface) A disk drive interface type which was briefly popular before IDE took over. An ESDI drive can transfer data between the drive and controller at 10, 15, or 20 megabits per second, which is faster than an MFM or RLL controller but slower than what is possible with an IDE or SCSI drive. See also IDE.

Exception A signal by the CPU that some error condition has been encountered that it can not deal with without a program's intervention. The most commonly encountered exceptions on Intel processors are Exceptions 12 and 13, which are stack and general problems, respectively. Exception 13 is typically caused by a memory access which wraps from the end of a segment back to the beginning.

Expanded Memory Specification A specification devised by Lotus, Intel, and Microsoft for accessing more than one megabyte of memory by bank-switching additional memory into the one megabyte real mode address space.

Extended BIOS Data Area A block of memory, typically the 1K at the top of conventional memory, which is used to store additional data for use by the BIOS which does not fit into the 256-byte data area at segment 0040h.

Extended File Control Block A DOS File Control Block which has had an additional seven bytes prepended to permit control of file attributes (which are stored in the appendage).

Extended Memory Memory beyond the one megabyte address which is available only on 80286 and higher machines. Except for a small portion (the High Memory Area), extended memory is only accessible from protected mode.

Extended Memory Specification A specification devised by Microsoft which allows multiple programs to share extended (above 1 megabyte) memory and noncontiguous memory above 640K.

External Device Interface A series of calls made by the DESQview multitasker on various "interesting" events, which may be intercepted by programs which wish to keep track of the current system state.

FAT see File Allocation Table

FCB see File Control Block

File Allocation Table A data structure on disk that records which clusters are free, which are unusable, and which have been allocated. The clusters occupied by a file are linked into a list in the file allocation table, allowing DOS to find the contents of the file.

File Control Block A data record in the calling program's address space which is used by DOS 1.x functions to record the state of an open file.

File Handle A small positive integer used to identify the previously-opened file on which a program wishes to perform an operation.

Flush To force the copying of any data still stored in temporary buffers to its final destination.

FM (Frequency Modulation) A method of encoding data as a series of magnetic flux reversals on disk or tape, commonly known as single-density recording. In frequency modulation, a series of clock pulses are written at regular intervals, with one data bit for each clock pulse. See also MFM, RLL.

Formatting Preparing a storage medium (usually magnetic media such as a disk or tape) for storing data. Low-level or physical formatting writes all necessary housekeeping data to enable the storage device to read the media and may also initialize the storage units on the media to a known state. High-level or logical formatting writes data used by the operating system, such as allocation information and directories onto media which has already been physically formatted. Formatting programs often perform both a low-level and a high-level format.

FOSSIL (Fido/Opus/Seadog Standard Interface Layer) A standardized API for performing serial I/O, originally used by the Fido and Opus bulletin- board software and Seadog bulletin-board mailer, but now in wider use.

FTP (File Transfer Protocol) The standard protocol for copying files from one machine to another on a TCP/IP (Internet) network. Also the program of the same name with which a user may transfer files.

Gather-Write see Scatter/Gather

Handle A short identifier, usually a small integer or a pointer, for some other object which is maintained or controlled by the operating system or environment; a particular handle may be valid system-wide or may have meaning only for a particular process. See also File Handle.

HGC (Hercules Graphics Controller) A monochrome video adapter capable of 720x352 monochrome graphics. The HGC was the first non-IBM video adapter for the IBM PC. See also CGA, MDA.

High Memory Area The first 65520 bytes (64K less 16 bytes) of extended memory. This area is accessible from real mode on the 80286 and higher processors because these processors do not wrap addresses at one megabyte as the 8088 and 8086 do. See also A20, INT 2Fh Functions 4A01h.

HMA see High Memory Area

Horizontal Retrace When a monitor has finished displaying a single scan line, it must move it electron beam(s) back to the left edge of the CRT, during which time it turns off the beam. On the original CGA (and some early clones), the only time one could access the display memory without causing "snow" was during the horizontal or vertical retrace periods, as the display adapter was not itself accessing the display memory during those times. See also Vertical Retrace.

IDE (Integrated Drive Electronics) A type of disk drive interface which essentially extends the PC's expansion bus all the way to the drive and places the drive controller on the disk drive itself. See also ESDI.

IFS see Installable File System

Installable File System An Installable File System which allows non-DOS format media to be used by DOS. In most ways, an IFS is very similar to a networked drive, although an IFS would typically be local rather than remote.

IP (Internet Protocol) The lower level (transport layer) of the TCP/IP protocol suite. IPC (Inter-Process Communication) Any one of numerous methods for allowing two or more separate processes to exchange data.

IPX (Internetwork Packet Exchange) A low-level layer of Novell's NetWare networking software.

IRQ (Interrupt ReQuest) A hardware line connected to the interrupt controller chip which signals that a CPU interrupt should be generated.

ISA (Industry-Standard Architecture) The expansion bus used by the IBM PC/AT. See also EISA.

JFT see Job File Table

Job File Table The Job File Table (also called Open File Table) stored in a program's PSP which translates handles into SFT numbers.

LCD (Liquid Crystal Display)

List of Lists An internal DOS table of lists and other tables through which most DOS-internal data structures may be reached. See INT 21h Function 52h.

Little-Endian One of the two major ways of organizing multi-byte numeric values in memory. A little-endian layout places the least significant byte of the value in the lowest (first) memory location, i.e. 12345678h is stored as 78h 56h 34h 12h. Intel processors are little-endian. Compare Big-Endian.

LPT Abbreviation for Line PrinTer.

MCB see Memory Control Block

MCGA (Multi-Color Graphics Array) The low-end color adapter offered in IBM's early PS/2 series machines.

MDA (Monochrome Display Adapter) A text-only video adapter introduced together with the original IBM PC.

Memory Control Block The data structure containing the length and owner (among other things) of a portion of the memory managed by DOS. See INT 21h Function 52h.

MFM (Modified Frequency Modulation) A method of encoding data as a series of magnetic flux reversals on disk or tape, commonly known as double-density recording. In contrast to FM, modified frequency modulation omits all clock pulses except those between pairs of zero bits.

Mickey The smallest increment of motion a mouse can sense.

MIDI (Musical Instrument Digital Interface) A standardized interface for controlling musical instruments with a computer.

Modem (contraction of MOdulator/DEModulator)

Multitasking Any of a number of methods by which multiple programs may execute concurrently, with rapid switching between the programs giving the appearance that all are executing simultaneously.

MZ The letters M and Z appear in numerous places in DOS (memory control blocks, .EXE header, etc.); the conventional explanation is that these are the initials of Mark Zbikowski, one of the principal architects of MSDOS 2.0.

NCB see Network Control Block

NDIS (Network Driver Interface Specification) A hardware-independent network interface developed by Microsoft and 3com.

NetBIOS One of a number of low-level device-independent network interfaces; the other major interfaces are Novell's IPX and the Internet's IP (Internet Protocol, the lower-level portion of TCP/IP).

Network Control Block A Network Control Block used to pass requests to NetBIOS and receive status information from the NetBIOS handler.

Network Redirector A program which permits access to network devices (disks, printers, etc.) using the MSDOS kernel network redirector interface.

Network Shell A program which permits access to network devices (disks, printers, etc.) by intercepting DOS calls before they reach the DOS kernel and handling those operating on network devices while passing through actions on local devices.

NMI see Non-Maskable Interrupt

Non-Maskable Interrupt An interrupt which can not be disabled by clearing the CPU's interrupt enable flag, unlike most normal interrupts. Non-maskable interrupts are typically used to signal calamities which require immediate action, such as a hardware failure or imminent loss of power.

Non-Volatile RAM Memory which can be modified like normal RAM but does not lose its contents when the system's power is turned off. This memory may be powered by a battery when the system power if off, or it may be a type of memory which does not need electricity to maintain its contents, such as EEPROM or bubble memory.

NVRAM see Non-Volatile RAM

ODI (Open Data-link Interface) A hardware-independent network interface developed by Novell, Inc.

Open File Table see Job File Table

Overscan Area The "border" between the edge of the area where graphics or text can be displayed and the actual edge of the area the video adapter can illuminate on the monitor's screen.

Overscan Register On a display adapter, the control register which specifies the color to be displayed in the overscan area.

Packet Driver Any one of the numerous drivers conforming to FTP Software's Packet Driver Specification, which provides a hardware-independent network interface.

Page Fault A CPU-generated signal, and the operating system's reaction to it, generated when a program accesses a page of virtual memory which is not located in RAM at the time. The operating system's response is to load in the required page, possibly writing some other page out to disk in order to make room.

Palette Register A memory location on the video controller which specifies the actual color displayed for a particular color number.

Park To move a hard disk's read/write heads to a position in which it is safe to turn off the power and transport the disk drive. Many drives also lock the heads into position when they are parked, providing additional protection from sudden movement.

Pel see Pixel

Pixel A picture element, the smallest addressable unit of a graphical display.

Post Make known, either generally or to a specific handler, that a particular event of interest has occurred.

POST see Power-On Self-Test

Power-On Self-Test A brief examination of the system's functionality performed each time the system is turned on.

Print Spooler see SPOOL.

Program Segment Prefix The Program Segment Prefix is a 256-byte data area prepended to a program when it is loaded. It contains the command line that the program was invoked with, and a variety of housekeeping information for DOS.

Protected Mode One of the operating modes of the 80286 and higher Intel processors, in which addresses used by programs no longer correspond to physical addresses and the CPU enforces various protection mechanisms designed to prevent one program from disrupting other programs or the operating system.

PSP see Program Segment Prefix

PWORD Six bytes. Used to hold an 80386 protected-mode "far" address, consisting of a segment selector and a 32-bit offset, or a Turbo Pascal "real" variable.

QWORD (quad-word) Eight bytes.

RAM (Random Access Memory)

Real Mode One of the operating modes of the 80286 and higher Intel processors, and the only operating mode of the 8088, 8086, 80186, and 80188 processors. In this mode, all addresses used by programs correspond directly to real physical addresses (thus the full name, Real Address Mode) and there are no CPU-imposed protections between programs.

Real-Time Clock A battery-powered clock which continues to maintain its time even while the system is powered down. On PCs, the real-time clock contains a small amount of battery-powered memory (set CMOS RAM).

Redirector Interface The set of device-independent INT 2Fh function calls invoked by the MSDOS kernel to operate on devices it recognizes as network devices. These function calls provide a lower-level interface than the INT 21h calls made to DOS, allowing a program intercepting these functions to be simpler than one intercepting INT 21h calls. See INT 2Fh Functions 1100h through 1130h.

Refresh The process of periodically rewriting the contents of a DRAM memory chip to keep it from fading. The term "refresh" is also commonly applied to redrawing the image on a CRT's phosphors.

RGB (Red-Green-Blue) The color specification mechanism normally used in computer displays, where colors are separated into their primary-color components. .

RLL (Run-Length Limited) A method of encoding data as a series of magnetic flux reversals on disk or tape. RLL can achieve higher data densities than MFM recording because it encodes the data such that (on average), fewer than one flux reversal per data bit is required (however, timing becomes more critical). RLL is actually an entire family of encoding methods, specified with two numbers indicating the minimum and maximum distances between one bits (flux transitions). The variant normally called RLL is RLL-2,7; RLL-1,7 and RLL-3,9 are also in use. MFM is in effect RLL-1,3.

ROM (Read-Only Memory) A memory for program storage which may not be changed by the program as it runs.

RTC see Real-Time Clock

Scan Code The actual key number sent by the keyboard, which differs from the key codes seen by application programs. The enhanced (101/102-key) keyboard actually sends different scan codes than the original (83/84-key) IBM keyboard, but these are normally translated by the keyboard controller into the scan codes used by the original keyboard before they become visible to programs.

Scatter/Gather A technique in which the contiguous data of a disk sector or sectors is transferred to or from multiple non-contiguous areas of memory. When reading into multiple areas of memory, this is called a scatter-read; the opposing operation is called gather-write.

Scatter-Read see Scatter/Gather

SCSI (Small Computer Systems Interface) A system-independent expansion bus typically used to connect hard disks, tape drives, and CD-ROMs to a computer. A host adapter connects the SCSI bus to the computer's own bus. .

SDA see Swappable Data Area

Sector The smallest addressable unit of data on a disk; under MS-DOS, this is normally 512 bytes.

SFT see System File Table

SPOOL (Simultaneous Peripheral Operation OnLine) The process of performing output to a slow peripheral such as a printer while other tasks continue running on the CPU. This term dates back to mainframe days before the invention of timesharing.

SQL (Structured Query Language)

SRAM (Static Random Access Memory) RAM which typically consists of one flip-flop per bit of memory. Unlike DRAMs, static RAM retains its contents as long as power is applied. Because there is no need to refresh the contents of memory addresses which are read, SRAM is faster than DRAM, but it is more expensive and typically is available in much smaller sizes than DRAM because each bit occupies more space on the chip.

SVGA (Super VGA) A video adapter capable of higher resolution (pixels and/or colors) than the 320x200x256 and 640x480x16 which IBM's VGA adapter is capable of producing.

Swappable Data Area The portion of the DOS data segment containing all of the variables used internally by DOS to record the state of a function call in progress.

System File Table A System File Table is a DOS-internal data structure used to maintain the state of an open file for the DOS 2+ handle functions, just as an FCB maintains the state for DOS 1.x functions.

TCP (Transmission Control Protocol) A higher level (session layer) of the TCP/IP protocol suite.

TCP/IP The protocol suite originally developed by DARPA for use on its ARPAnet network, which is now known as the Internet.

TSR (Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user. The name comes from the name of the DOS function call used to remain in memory after termination.

Track One of multiple concentric circular rings of data on a single data-bearing surface of a disk. Tracks at the same location on different surfaces form a cylinder.

UMB see Upper Memory Block

UNC (Universal Naming Convention) The standard way of describing network servers and their directories under MS-DOS and Windows NT. A name in UNC format consists of two backslashes followed by the server name, optionally followed by another backslash and a list of backslash-separated fields; for example \SERVER1\SHARED-DIR\SUBDIR1\SUBDIR2\FILENAME.EXT.

Upper Memory Block A noncontiguous section of allocatable memory located between the 640K and 1024K addresses.

V86 see Virtual-86 Mode

VCPI see Virtual Control Program Interface

VDM see Virtual DOS Machine

VDS see Virtual DMA Specification

VDU (Video Display Unit) Mainframe-speak for computer monitor.

Vertical Retrace When a monitor has finished displaying an image by sweeping its electron beam(s) over the face of the CRT, it has to move the beam back up to the top of the display. During the time this takes, the beam is turned off. The vertical retrace interval is a good time to change the displayed picture for smooth animation.

VESA (Video Electronics Standards Association) An industry group which sets both hardware and software standards and recommendations. The term VESA is also used to denote compliance with the VESA SuperVGA BIOS Extensions, a standard set of video BIOS functions for accessing video modes of higher resolution than those defined by IBM.

VGA (Video Graphics Array) The video adapter introduced with the IBM PS/2 series of computers.

Virtual-86 Mode One of the operating modes of the 80386 and 80486 processors in which user programs run as if the CPU were in Real Mode, while providing the protection and address-mapping capabilities of Protected Mode to a supervisor program which oversees the virtual machine on which the user programs are running. This mode is called Virtual-86 because one or more virtual 8086 environments are run on a single CPU.

Virtual Control Program Interface A simple API for protected-mode programs to allocate memory and switch into or out of protected mode.

Virtual DMA Specification A set of interrupt calls which permit the use of DMA even on systems running in protected or Virtual-86 mode with their address remapping, or systems such as Micro Channel PS/2s with multiple bus masters independently performing DMA operations.

Virtual DOS Machine A special type of virtual machine provided by OS/2 version 2.0, in which a copy of MS-DOS or an MS-DOS compatible operating system (or even an incompatible 8086 operating system) is run and appears to have full control of the system.

Virtual Machine One method for multitasking programs is to virtualize the CPU and other hardware, giving the appearance of sole possession of the system to each program being run. Such a virtualized environment is called a virtual machine.

virus A program which attaches itself to other programs for the purpose of duplicating itself. Viruses often (but not always) contain harmful code which is triggered by some event, after a certain number of reproductions, or on a specific date.

VM see Virtual Machine

VxD A virtual device driver for Windows 3.0 or 3.1. S

WORM (Write Once, Read Many) A storage medium which may be written exactly once, but may not be altered once data is stored.