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15 Cards in this Set
- Front
- Back
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Instruction Set |
The patterns of 0's and 1's that a particular processor recognises as commands. |
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Opcode |
An operation code or instruction used in assembly language.
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Operand |
A value or memory address that forms part of an assembly language instruction. |
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Direct Addressing |
The operand is the datum. |
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Immediate Addressing |
The operand is the memory address or register number. |
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Function of a Camera |
When a photograph is taken, the shutter opens and lets light through the lens. The light is focused onto a sensor, either a CCD or a CMOS sensor The sensors are made up of millions of transistors, which each store the data for one or more pixels As the light hits the sensor, it is converted into electrons and the amount of charge is recorded for each pixel in digital form. All visible colours can be created from red green and blue light, so to record colour, the camera has three different sensors or filters which record the intensities of these three colours. The data are usually stored on removable storage devices referred to as flash memory Data are usually stored in compressed files such as PNG or JPG RAW files can also be generated which are uncompressed and therefor contain all the data from the original photo. |
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Function of Barcode Readers |
A red visible light is passed over the barcode. A light sensor measures the intensity of the light reflected back. White areas reflect the most light back whereas black areas reflect the least, creating a waveform of the barcode. The analogue waveform is converted into digital data. The data is then interpreted by a computer to identify the product data. A check digit at the end of the barcode ensures its validity. |
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Function of Laser Printer |
The files that require printing are sent to the printer using a page description language. The printer processes this file and creates a bitmap pattern for the page. The printer laser beam scans along and across the drum inside the printer creating the same pattern as the page that requires printing. This builds up a pattern of static electricity that attracts toner onto the page. The toner is then fused onto the page by heat and pressure. |
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Function of RFID Reader |
The tag contains an antenna used to communicate with the RFID reader.
The RFID reader transmits a radio signal which is received by the tag. The tag then returns the programmed information it contains to the reader. The code is then decoded and translated into digital data that is interpreted by the computer to identify the information received. Active tags contain their own power source and can have a greater range. Passive tags are charged by the radio signals of the reader but have a smaller range. |
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Function of Hard Disk |
Consist of a number of metal discs which are coated with a thin film of magnetic material. The discs are mounted on a spindle and rotated at high speed. A series of read/write heads move across the disc surface together to access or store data on the disc. |
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Function of the SSD |
Use non volatile NAND flash memory and a controller to manage pages, blocks and complexities of writing. The flash memory cells are grouped into a grid that is separated into sections called pages into which the data is stored A block consists of many pages. Pages cannot be overwritten individually; the whole block must be erased before the pages can be overwritten. Uses floating gate transistors which trap and store charge even when the power is off. |
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Advantages of the HDD |
Higher storage capacity than an SSD Cheaper than an SSD High data transfer rate |
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Advantages of the SSD |
Perform faster than HDD's as there are no moving parts. Very low latency compared to HDD's as a HDD must spin and position the read/write head over the disk to access data. |
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Function of the Optical Disk |
Binary data is pressed or burned into the surface of the disc as a series of pits and lands. A pit has a binary value of 0 and a land has a binary value of 1. Laser beams read the data stored on the disc since pits and lands reflect different amounts of light which can be decoded into the original binary data |
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Advantages and Disadvantages of the Optical Disc |
Advantages: Portable and cheap to produce Reasonable storage capacity Faster access time than magnetic tape Disadvantages: Care must be taken when handling as scratching renders the disc inoperative Less storage capacity than a hard disk so unsuitable for large volumes of data. Larger access time than for both HDD's and SSD's |
