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Computer Systems. Basic Components. Main Memory. Input. Processor. Output. Auxiliary Storage. Types of Input. Keyboard Mouse Barcode readers Scanners Voice data entry OMR OCR. Types of Output. Monitors (also known as VDUs or screens) Printers Plotters Other types ?.
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Basic Components Main Memory Input Processor Output AuxiliaryStorage
Types of Input • Keyboard • Mouse • Barcode readers • Scanners • Voice data entry • OMR • OCR
Types of Output • Monitors (also known as VDUs or screens) • Printers • Plotters • Other types ?
The Processor • Processing Power determined by: • Speed of operation of CPU • Amount of memory • Number of I/O devices it can handle • Some control functions of CPU: • Transmission of input data to memory • Process data held in main memory • Transmission of data from main memory to output devices
Made up of individual storage units calledbytes Total number of bytes is referred to as computer’s memory size: = 1,000 bytes (actually 1024) = 1,000,000 (1 million) bytes = 1,000,000,000 (1 billion) bytes = 1,000,000,000,000 (1 trillion) bytes Main Memory • 1 Kilobyte (Kb) • 1 Megabyte (Mb) • 1 Gigabyte (Gb) • 1 Terabyte (Tb)
RAM and ROM • RAM – Random Access Memory • Stores current programs and data. • It is VOLATILE – lost when switched off • ROM – Read-Only Memory • Non-VOLATILE. • Instructions or programs permanently etched onto a chip. For example, bootstrap loader.
Auxiliary Storage • Hard disk • Stores operating system, systems and application software, and data. • Typical sizes are now 15-20 Gb • Floppy disks • Typical HD disk has capacity of 1.44 Mb. • CDs • Typical capacity of 650-800 Mb. • Zip Disks • Capacity 100 and 250Mb disks. Internal or External models available.