21524334-Computer-Organization-Articture-No-8-from-APCOMS

21524334-Computer-Organization-Articture-No-8-from-APCOMS -...

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COA by Athar Mohsin Lecture 08 Basics of computer
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COA by Athar Mohsin The Register Registers are used in computer systems as places to store a wide variety of data, such as addresses, program counters, or data necessary for program execution. A register is a hardware device that stores binary data. Registers are located on the processor so information can be accessed very quickly Data processing on a computer is usually done on fixed size binary words that are stored in registers. • Therefore, most computers have registers of a certain size. Common sizes include 16, 32, and 64 bits. • The number of registers in a machine varies from architecture to architecture, but is typically a power of 2, with 16 and 32 being most common. Registers contain data, addresses, or control information. Some registers are specified as "special purpose" and may contain only data, only addresses, or only control information. Other registers are more generic and may hold data, addresses, and control information at various times.
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COA by Athar Mohsin The Register Information is written to registers, read from registers, and transferred from register to register. In modern computer systems, there are many types of specialized registers: registers to store information, registers to shift values, registers to compare values, and registers that count. There are "scratchpad" registers that store temporary values, index registers to control program looping, stack pointer registers to manage stacks of information for processes, status registers to hold the status or mode of operation (such as overflow, carry, or zero conditions), and general purpose registers that are the registers available to the programmer.
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COA by Athar Mohsin The Input/Output Subsystem Input and output (I/O) devices allow us to communicate with the computer system. I/O is the transfer of data between primary memory and various I/O peripherals. Input devices such as keyboards, mice, card readers, scanners, voice recognition systems, and touch screens allow us to enter data into the computer. Output devices such as monitors, printers, plotters, and speakers allow us to get information from the computer. A computer communicates with the outside world through its input/ output (I/O) subsystem. I/O devices connect to the CPU through various interfaces. I/O can be memory-mapped- where the I/O device behaves like main memory from the CPU’s point of view. Or I/O can be instruction-based, where the CPU has a specialized I/O instruction set.
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COA by Athar Mohsin I/O These devices are not connected directly to the CPU. Instead, there is an interface that handles the data transfers. This interface converts the system bus signals to and from a format that is acceptable to the given device.
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This note was uploaded on 01/06/2010 for the course CS it666 taught by Professor Tony during the Spring '06 term at 東京大学.

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21524334-Computer-Organization-Articture-No-8-from-APCOMS -...

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