|
Term |
Meaning |
Comments |
| ACIA
|
Asynchronous Communications Interface Adapter |
Also called UART. More |
| ACPI |
Advanced Configuration and Power Interface |
PC term |
| ACR |
Advanced Communications Riser, probably similar to an AMR |
PC term |
| A/D
|
Analog to Digital |
| ADC |
Analog to Digital Converter |
| ADMA
|
Advanced DMA* controller |
Siemens |
| ADPCM
|
Adaptive Differential Pulse Code Modulation |
Both the sender and the receiver predict what the next sample will bebased on the fact that the human voice and simple modem signals never containtwo frequencies at once and then instead of sending the complete 8 bits PCM* codeonly the difference is send in 4 bits. |
| ADTV
|
Advanced Definition TV |
| AGC
|
Auto Gain Control |
Adjusts input audio volume automatically. Not easy to do.May severely distort recordings. Beware! |
| AGP |
Accelerated Graphics Port |
This port was added after the PCI bus proved to be to slow for graphics.Disadvantage: Only one AGP slot per motherboardso multiple displays becomes more difficult.2002: Even low-cost ($90) modern AGP video cards can handle multiple displays now,although the second one is usually configured on the card to be a TV. |
| ALI |
ATM Line Interface |
TranSwitch |
| AM
|
Amplitude Modulation |
The amplitude variation of a wave carries a slower wave. |
| AMDM |
ATM Multiplexer/DeMultiplexer (QSI) |
| Amp
|
Amplifier |
Chipwise usually an OPerational AMPlifier (OpAmp*).There is also a company called AMP.They mainly make (good!) connectors. |
| AMR |
Audio Modem Riser. This is a small card you prick into the motherboard and it contains enough (dependend on country) hardware, so the CPU can emulate a (soft-) modem with it. |
PC term |
| AND
|
The logical AND* function. |
The output is high if and only if all inputs are high. |
| AOI
|
And-Or-Invert |
First a couple of AND-ports, whose outputs go into a single NOR* port.The last inversion is probably because NOR* ports are fasterthen OR*'s and because ports with inverted outputs offer more possibilities. |
| APM |
Advanced Power Managament |
PC term |
| ARCOFI
|
Audio Ringing COdec* FIlter |
Siemens |
| ASLAC
|
Advanced Subscriber Line Audio processing interface |
AMD |
| ASLIC
|
Advanced Subscriber Line Interface |
AMD |
| Async
|
Asynchronous |
Not clocked, so just a bunch of logic ports one after another. |
| atto
|
10**-18 |
|
Term |
Meaning |
Comments |
| Baud
|
Unit for baudrate* (next entry). |
| Baudrate
|
Signal level changes per second. |
Often confused with BPS*. Named after mister Baudot.In early modems the baudrate* was equal to the BPS*, hence the confusion. |
| BCP
|
Biphase Communications Processor |
NS |
| BinHex
|
The Apple way to code binary files using visible ASCII-onlyto fascillitate sending the data over pure-ASCII (or unknown) networks. |
The UNIX variation is UUEncode. Usually the datastream is chopped in parts ofsix bits and ' ' is added. This has the extra advantage that only upper casecharacters are used. Old computers couldn't handle lower case letters.More. |
| BIOS |
Basic Input Output System, the (EEP)ROM that handles how a PC starts up |
PC Term |
| BPS
|
Bits Per Second |
This is relevant for serial connections. Beware that the nominal and actual bitratemay differ depending on the reliability of the medium. Once a medium has a certainreliability you can enhance it's reliability to whatever you like by sacrificingspeed. |
|
Term |
Meaning |
Comments |
| CAD
|
Computer Aided Design |
Using a computer to design products. For PCB CAD* programs see local. |
| CAM
|
Computer Aided Manufacturing |
It's the next step after CAD*. Together they are often called CAD*/CAM*.See also the next entry. |
| CAM* |
Content Addressable Memory |
The memory is not addressed according to it's linear address but by it's content,usally some sort of tag to gain access to the real data. This kind of memory wasoriginally often used to implement MMU*'s. Currently two-way associativelook aside buffers are more common, because they can work faster (less drain onthe address lines). This means that the part of the address lines that are usedfor associative purposes becomes smaller and the deterministic part bigger.With a two way caching mechanism however you can get into serious caching problemswhen copying arrays etc.For example when adding the elements of two screen image arraysand putting it in the video RAM. |
| CAN |
Controller Area Network |
Type of network. |
| CC
|
C compiler |
Compiler for the language C |
| CCD
|
Charge Coupled Device |
Kind of DRAM, that can sense light intensities.local. |
| CDB
|
Cell Delineation Block device |
TranSwitch |
| CDR
|
Clock and Data Recovery |
TranSwitch |
| CISC
|
Complex Instruction Set Computing |
As opposed to RISC.CISC* was the classic way of designing processor instruction set.It was based on the misapprehention of the hardware designers that theprogrammers were still programming in Assembler and wanted powerful addressing modes.Compilers don't like complex instructions however. |
| CMOS
|
Complementary Metal Oxide Semiconductor |
The 4xxx range was a very popular range of early glue semiconductors.It's already very old (1980 or earlier), both on those days static was a problem with CMOS*.Later CMOS* became the standard in the industry because of it's low energy consumptionand even modern TTL (since about 1985?) is done in CMOS* (HCT*). See local. |
| CNR |
Communication and Networking Riser, probably similar to AMR |
PC term |
| Codec
|
COder and DECoder |
This is a combined ADC and DAC for telecom purposes.The digital format is usually A-law or µ-law PCM*.More. |
| COFF |
Meant to be a universal format for binary files. |
Every computer type uses it's own variation however. |
| COFI
|
COdec* FIlter |
| COFISLIC
|
COdec* FIlter and Subscriber Line Interface Circuit |
AMD |
| CompactPCI |
Passive backplane specification for (industrial) PCI. |
| CPU |
Central Processing Unit |
This is called MPU on these pages, because we're only thinking in terms of chips here.CPU's were once implemented as many-IC PCB's in mainframes and mini computersand therefore single chip CPU's were called microprocessors or MPU's.Nowadays all CPU's are single chip and the makers of big computerstry to put as many of them in a single computer to offer as much power as possible. |
| CRIMM |
Continuity RIMM |
PC term? |
| CRT
|
Cathode Ray Tube |
This is the basic part of a video monitor that actually shows the images.A television set has additional circuitry to decode and select one outof several broadcasting channels and to handle audio, teletext and in future evenmuch more. |
| CTC
|
Counter Timer Circuit |
Counters and timers are basically the same because timers just count time ticks.However since we see time as an absolute continuum, in our nativity we tend to makea difference. |
I once had to program a system that at any moment might have access to:
- the system time (from the crystal)
- the RTC time (from a battery-fed Philips chip)
- the DCF-77 receiver time
- the user time (users always seem to know better what time it is ;-)
|
Add that you can also get the time via all kinds of networks or by dialing inand the problem gets even more complicated. |
|
Term |
Meaning |
Comments |
| D/A
|
Digital to Analog |
| DAA |
Data Access Arrangement |
| DAC |
Digital to Analog Converter |
MPU's and MCU's 'think' digitally so to convert these 'thoughts' to the real worldwe need to convert this, usually parallel binary, data to an analogue voltage orcurrent.The simplest solution is using a resistor network costing only a few dimes.Another cheap solution is generating a square wave with a certain high-lowratio (duty cycle) and feeding that via a resistor into a capacitorwhich will then average it out.There are also much more sophisticated solutions. The company 'Analog' got bigspecializing on this. |
| DART
|
Dual* Asynchronous Receiver Transmitter |
Two UART's |
| DCF-77 |
Time info transmitter in Mainflingen, Germany. |
Only usable in a circular area around the transmitter in Europe.local. |
| DCPAT
|
Dual* CEPT Primary Access Transceiver |
AT&T |
| DD
|
Double density |
Floppy disk type. DD* uses a more advanced bit coding than Single Density (SD*).SD* and DD* floppies are the same. See also High Density (HD*). |
| DDR |
Double Data Rate. DRAM with this feature can be read on both flanks of the clock signal, doubling the amount of data they can provide with the same clock rate. Currently (2002) it's mainly a technology used on video cards, I think. |
| DDS
|
Direct Digital Synthesis |
The IC*'s AD7008 and AD9850 from Analog Devices are oftenused as computer controlled signal generators in highend RF applications.The integrated circuits generate a high quality sinewave with nearlyconstant amplitude between about 0,01 Hz and 65 MHz.Frequency and phase angle of the output signal are being varied by serial input data.The ideal circuit for HAM radio ;-) |
| Demux
|
Demultiplexer |
| DIMM |
Dual* Inline Memory Module |
modern type of DRAM memory on a small plug-in board, see also SIMM. Early PC motherboards used sockets for DRAM chips, but it was very hard to predict which memory chips would be cheap once the board was finished. It's easier to put SIMM/DIMM sockets on the board and let others take care of the issue, which chips to put on them. |
| DMA
|
Direct memory access |
See next entry |
| DMAC
|
Direct memory access controller |
This is a separate, very simple but fast co-processor (consisting mainly of counters)that is allowed to handle the address and data lines of the system(after being instructed to do so by the main processor).It will either 'steal' single cycles on the bus or do 'burst' accesses, mainly to do I/O.The usefulness of DMA* during a certain era depends heavilyon the difference in speed between the processor and the system and it's interrupt overhead.It also depends on if the peripheral will need to be serviced regurarly with singlebytes or small blocks or that it can buffer data itself and do a burst just now andthen. With the current trend to put more and more memory and intelligence in theperipherals and CPU's getting faster and faster DMA* is gradually gettingmore and more obsolete.Even modern UART's already have an internal 64 bytes bufferso the CPU can handle them and DMA* is not needed. |
| DMI |
Direct Management Interface |
PC term |
| DPST
|
Double Pole, Single Throw |
Type of switch |
| DRAM |
Dynamic Random Access Memory |
See DRAM |
| DRM |
Dual* Rentention Mechanism |
PC term |
| DS
|
Double sided |
Floppy disk term |
| DSP |
Digital Signal Processor |
See DSP. |
| DSR
|
Dynamic Shift Register |
Also RS-232 term: Data Set Ready. DTR means 'Data Terminal Ready'.'Set' means 'modem' since RS-232 mainly dealed with the terminal-modem connection situation.A PC was traditionally seen by IBM as a terminal and not as a real computer... |
| DTMF |
Dual* Tone Multi-Frequency |
This is the system to code special information over a traditional analoguetelephone line. Normally a single person only uthers one frequency at a time.By sending two frequencies at the same time for a certain time (about 0.1 s)it's possible to make quite sure not to get these tones confused with humanspeech. The frequencies are choosen such that they have no harmonics in common.For a receiver, check out the Mitel MT8870 (second sourced by Samsung).For a sender check out the Philips I2C part PCD3311, PCD3311A or PCD3312. |
| Dual
|
Containing 2 equal devices |
| DUART
|
Dual* Universal Asynchronous Receiver Transmitter |
Device with two UART's |
|
Term |
Meaning |
Comments |
| ECL
|
Emitter Coupled Logic |
Is very fast and expensive |
| ECP |
Extended Capabilities Port |
PC term |
| ECC |
Error Checking and Correcting. Parity can only detect errors, but ECC can also repair it, assuming that there are only single bit errors now and then. It requires only 30% or such more bits to be transmitted. Check a good book about datacommunication about this subject... |
| EDO-RAM
|
Extra (Extended?) Data Output RAM |
See also DRAM |
| EDTV
|
Enhanced Definition TV |
| EEPROM |
Electrically Erasable Programmable Read Only Memory |
| EMC |
Electro Magnetic Compatibility |
| EPP |
Enhanced Parallel Port |
Enhancement of the parallel printer port of the PC. The first port only had 8 data bits out and 4 control lines in and a handshake line, I think (see Centronix port). Later enhancements include 8 bits in and out and bididrectional features etc. Look in this Chipdir's ABC under the P for more info. |
| EPROM
|
Erasable Programmable Read Only Memory |
| ESCD |
Extended System Configuration Data |
PC term |
| ESD |
Electro Static Discharge |
| Euro-AV/SCART* |
See SCART* |
| Exa
|
10**18 or for computers 1024**6 |
|
Term |
Meaning |
Comments |
| FAQ |
Frequently Asked Questions |
| FCODE
|
Forth Code |
Processor independent language to write device drivers for the PCI-BUS.local. |
| FDC
|
Floppy Disc Controller |
This is the chip (or formally the board) that controles the floppy disc drive.Basically there are two families: The 1771 family by Western Design/Digital Corporation (?)and the 765 family by NEC (same as 8272 by Intel, but who did really design it?). |
| FDD |
Floppy Disk Device |
This is a floppy disk drive |
| femto
|
10**-15 |
| FET
|
Field Effect Transistor. |
This is a voltage driven transistor.(The much more popular PNP and NPN transistors are current driven.) |
| FFT
|
Fast Fourier Transformation |
This is a method to transform data from the time domain (that we normally live in)to the frequency domain (which is only interesting for freaks who want to studytrends in signals). Of course those freaks make a good living of off their knowledgebecause examining trends can be big business.Simple consumers like us may notice FFT* in our hifi sets when it has a displaywhich shows the energy in different frequency ranges. |
| FIFO
|
First In First Out |
Like in a queue in the post office.The alternative is a stack or LIFO (Last In First Out). |
| FM
|
Frequency Modulation |
A slower wave is carried by the small frequency variations of a carrier wave.The predecessor was AM* which carried it's child wave using variations in amplitude.This however was much more prone to distortions, because the amplitude of a signalsuffers from all kinds of reflections etc. FM* uses more bandwidth in turn however. |
| FPAA |
Field Programmable Analog Array |
Enables building fast analog circuits. Motorola seems to have left this field now... |
| FPDRAM
|
Fast Page DRAM. |
Outdated by EDO and SDRAM* etc. |
| FPGA |
Field Programmable Gate Array |
This is a 'cheap' way to design your own chips. All the components are already on thechip, but 'in the field' you program them to make the right connections between thecomponents.Cheap is not really true for large amounts since the chip will use a lot of energyfor the components that you're not really using. These components are also expensivebecause they carry a lot of unused silicon around. They may also be slow. Startup timemay be hindered by the fact that their functionality needs to be loaded from a serial ROM.The software needed to achieve the functionality may also be expensive and gettingused to the software may also take time. However once the design is readyand tested there may be an easy path to having the design being mass produced in a realASIC. Xilinx became big making these FPGA's. |
| FSB |
Front Side Bus |
| FS-PAL
|
Field Sequential Phase Alternation Line |
| FYI
|
For Your Information |
|
Term |
Meaning |
Comments |
| HCMOS
|
High-speed Complementary Metal Oxide Semiconductor |
| HCT
|
High-speed CMOS* TTL compatible |
| HD
|
High density |
Floppy disk type. HD* uses the same coding as DD*, but just reads and writestwice as fast. |
| HDD |
Hard Disk Device/Drive |
PC term |
| HDSL |
| HDTV
|
High Definition TV |
A TV with a higher resolution on screen. |
| Hex
|
Containing 6 equal devices |
Also: Hexadecimal (16) base notation for numbers. |
| HP |
Horse Power |
On switches. A switch must be rated for as many horsepower as the motor it can switch on and off. |
| HPC
|
High Performance microController |
Old term used by NS. Look under MCU.Can also mean: Hand-held Personal Computer, High Performance Computingor High Pressure Compressor |
| HQX
|
File name extension of BinHex* files |
See BinHex*. |
| HV-SLIC
|
High Voltage Subscriber Line Interface Circuit |
|
Term |
Meaning |
Comments |
| M13
|
DS1/DS3 Multiplexer |
TranSwitch |
| M13E
|
DS1/DS3 Multiplexer Extended features |
TranSwitch |
| MAC
|
Multiplexed Analogue Components |
| MCU |
See MCU |
| mega
|
10**6 = 1000*1000 |
For computers 2**20=1024*1024 and for harddisks sometimes even 1000*1024 |
| MEMS
|
MicroElectro Mechanical Systems, see for example: www.memsrus.com/ |
| MFAST
|
Mwave Folded Array Signal Transform (IBM) |
| MFLOPS
|
Mega* Floating Point Instructions Per Second |
| MHz |
Mega* HertZ |
1000,000 times per second |
| micro
|
10**-6 |
| MIDI |
Musical Instrument Digital Interface |
| milli
|
10**-3 |
| MIPS |
| MMU
|
Memory Management Unit |
| Modem |
Modulator/demodulator |
(follow the link). |
| MOS
|
Metal Oxide Semiconductor |
As in CMOS* |
| MOSFET
|
Metal Oxide Semiconductor Field Effect Transistor (FET*) |
| MPT |
Memory Protocol Translator |
PC term |
| MPU |
Micro* Processor Unit (=single chip CPU) |
| MSI
|
Medium Scale Integration |
| MTH |
Memory Translator Hub |
PC term |
| MUART
|
Multifunctions Universal Asynchronous Receiver Transmitter |
| Mudem
|
Multiplexer and Demultiplexer |
Not an official term |
| Mux
|
Multiplexer |
|
Term |
Meaning |
Comments |
|
PAC
|
Primary Access framer/Controller |
AT&T |
| PCI AGP Controller |
PC term |
| PAL
|
Programmable Array Logic (=chip) orPhase Alternation Line (=European color television standard) |
| PBSRAM
|
Pipeline Burst SRAM* |
Used as cache |
| PCB |
Printed Circuit Board |
| PCI |
Peripheral Component Interconnect |
PC and Macintosh bus |
| PCM
|
Pulse Code Modulation |
| PEEL
|
Programmable Electrically Eraseable Logic |
See ICT. |
| Peta
|
10**15 or for computers 1024**5 |
| PIA
|
Parallel Interface Adapter |
| PIC |
Peripheral Interrupt Controller (Intel) orPeripheral Interface Controller (MicroChip) |
| pico
|
10**-12 |
| PIO
|
Parallel Input Output |
Usually called PIA* |
| PIPO
|
Parallel in parallel out |
| PISO
|
Parallel in serial out |
| PLA
|
Programmable Logic Array |
| PLD |
| PLL
|
Phase Locked Loop |
| PMOS
|
P-type Metal Oxide Semiconductor |
| POST |
Power-On Self Test |
PC term |
| PROM
|
Programmable Read Only Memory |
| PSRAM
|
Pseudo SRAM* which is basically the same as dynamic RAM with on-chip refresh circuitry.Same stuff from Sharp is called "SmartCombo SRAM*".The trade-off is: Lower cost, but slightly higher current consumption in low power mode.Stig Nielsen. |
Intel |
|
Term |
Meaning |
Comments |
| UART |
Universal Asynchronous Receiver Transmitter |
| µC |
Micro* Controller |
Same as MCU. It's a small micro* processor combined with a couple of peripherals on a chip |
| ULSI
|
ultra large scale integration |
| UMPS |
Modeling language for CPU cores |
www.vmdesign.com/ |
| µP |
Micro* Processor (=MPU or CPU) |
| UPI
|
Universal Programmable Peripheral Interface |
Intel terminology |
| UPS
|
Uninterruptable Power Supply |
This will keep your computer or other equipment runningfor a while more (about 15 minutes) after the 110/220V has gone,so it can still finish tasks and power down your computerin a controlled way.It may also guard against spikes on the 110/220V etc.It will usually contain some sort of accu.If you want to keep your computers running longer you'll needan aggregate running on some sort of fuel. |
| USART
|
Universal Synchronous/Asynchronous Receiver/Transmitter |
This is a UART that can also work in synchronous mode.Synchronous means that the data isn't send in bytes with a start and stop bit around it,but the data bits are send continously. The bit clocks of the two USART*'s need tobe synchronized in another way (for example via an extra line). |
| UTP
|
Unshielded Twisted Pair |
This is a cheaper alternative for coax cable. Coaxial cable has the inner wirecompletely shielded by the other cable which is wooven around the inner one(and a tube of isolating material).This way magnetic fields can't influence the inner wire.Twisted pair cable hastwo wires that are wound around each other. This way both wires should experiencethe same fields and therefore both signals are distorted the same way.By subtracting the two signals from each other in the receiverthe distortions are removed again. |
|
Term |
Meaning |
Comments |
| VBAP
|
Voice Band Audio Processor |
TI |
| VCA
|
Voltage controlled amplifier |
| Vcc
|
Main power supply |
Generally 5V |
| VCO |
Voltage controlled oscillator |
| Vdd
|
Secondary power supply |
| Vee
|
Negative power supply |
| VESA
|
Video Electronics Standards Association |
VGA-interface and Local-Bus-definition |
| V/F
|
Voltage to Frequency (=VCO) |
| VGA |
| VLSI |
Very Large Scale Integration |
| Vpp
|
Programming power supply |
Generally higher then Vcc* |
| VRAM
|
Video Random Access Memory |
Serial and/or dual* access(?) |
| VSS
|
Also some sort of ground |
| VtoF
|
Voltage to Frequency converter |
Same as VCO |
