| A | B |
|---|
| Mouse | uses a roller ball to control the curse on the screen. Can be 2 or 3 buttons |
| Light pen | is a handheld input device that contains a light source or can detect light. It is pointed at the screen to identify a position on the screen |
| Graphics tablet | Consists of a flat, rectangular, electronic plactic board used to input drawing, sketches or other graphics data |
| Image scanner | Converts the image dot by dot, line by line into a stream of binary numbers |
| Keyboard | character based device - consists of a number of switches and a keyboard controller |
| Barcode reader | Uses laser beams to read bar codes. Converts a visual scan into binary signals |
| Optical Character Recognition (OCR) | Scans the shape of a character, compares it with a predefined shape stored in memory, and converts the character into corresponding computer code |
| Optical Mark Recognition (OMR) | Used for processing questionnaires and test answer sheets |
| Magnetic Ink Character Recognition (MICR) | Uses a special ink that can be magnetised during processing. Used by the banking industry for processing checks |
| CRT Monitor | Same technology as TV screen |
| LCD Monitor | Best choice for portable computers |
| Gas Plasma | uses neon gas instead of liquid crystal material |
| Dot Matrix Printer | Print head contains column(s) of pins which are struck against paper through inked ribbon |
| Dot Pitch | Distance between two pixels |
| Monitor size | Measured diagnonally across the screen |
| Types of output | Reports, Graphics, Audio, Video |
| Laser Printer | High quality printer |
| Ink Jet Printer | The print cartridge moves across the page to print a row. |
| The Bus | A collection of parallel wires or lines used for transferring data, instruction and address of data |
| CPU Bus Types | Address Bus, Data bus, Control bus |
| Address Bus | Used to select memory address or location. Depending on the type & size of CPU, can be 8-, 16-, 20-, 32- bit |
| Data Bus | Used to carry data or "address of the data" between main memory and the CPU and vice versa |
| Control Bus | Is used to carry control signals (eg. READ, WRITE, HALT) to perform specific operations |
| Word Size | Number of bits that the CPU can process at one time |
| ALU | Arithmetic and Logic Unit |
| CPU | Central Processing Unit |
| CU | Control unit |
| Hex | Hexadecimal number |
| ASCII | American Standard Code for Information Interchange |
| EBCDIC | Extended Binary Coded Decimal Interchange Code |
| Unicode | A new 16-bit code, support many different languages |
| A | Accumulator |
| PC | Program counter |
| IR | Instruction Register |
| MAR | Memory Address Register |
| MDR | Memory Data Register |
| SR | Status Register |
| Main Memory | Also called primary memory eg. RAM |
| Secondary Memory | Also called storage, eg Hard disk, tapes, Compact disk |
| Measurement for size of memory | Bytes |
| WAN | Wide Area Network |
| LAN | Local Area Network |
| MAN | Metropolitan Area Network |
| PSTN | Public Switched Telephone Network |
| ISDN | Integrated Services Digital Network |
| PSN | Packet Switching Network |
| DDN | Digital Data Network |
| READ operation | Used to read or retrieve data from the memory |
| WRITE operation | Used to write or store data into the memory |
| LOAD | The generic name of group of instructions that place a value or copy the contents of memory location into a register |
| STORE | The Generic name of a group of instructions that store the contents of a register into a memory location or memory locations |
| ADD | The Generic name of group of instructions that perform the addition operation |
| SUB | the generic name of group of instructions that perform the subtraction operation |
| Read only Memory (ROM) | Non-volatile: memory contents are retained even when the power is turned off |
| Random Access Memory (RAM) | Volatile: Memory contents are LOST when the computer is turned off |
| Complementary metal-oxide semiconductor (CMOS) | Stores a PC's set-up information |
| Dynamic RAM (DRAM) | Based on capacitor charge . Must be periodically refreshed to hold data and programs |
| Static RAM (SRAM) | Faster than DRAM but dearer and bulkier |
| SIMM | A small circuit board that has multiple DRAM chips on one side |
| DIMM | Similar to SIMM but has DRAM chips on both sides |
| Memory Speed | The time it takes to find data and retrieve it. Also called "access time" |
| Nanoseconds | Measurement of memory speed |
| PROM | Programmable ROM |
| EPROM | Erasable programmable ROM |
| EEPROM | Electronically erasable Programmable ROM |
| Function of Memory | the place where instructions and data are held while program is actually running |
| Drive | A mechanism that spins a disk or winds a tape |
| C:, D: | letters assigned to the hard drive |
| Seek TIme | TIme that is required to move head from one track to another |
| Rotational delay | Time required for disk to rotate to the beginning of the correct sector |
| Transfer time | Time required to transfer a block of data from disk to memory |
| Access time | Seek time + rotational time + transfer time |
| Magneto-Optical Storage | Uses magnetic and optical technology to read and write data |
| RAID | Redundant Array of Independent Disks |
| Sensor | Monitor environmental factors that might affect the process |
| Actuators | Adjusts the inputs accordingly |
| Host | Centralised computer where all the processing is done |
| Terminal | Device (containing monitor and keyboard) by which we access the host computer to do the task |
| Star | Each computer has a dedicated point-to-point link only to a central controller called a Hub |
| Hana | Your special lady |
