Computer architecture: Difference between revisions

Revision as of 15:51, 25 February 2002

Revision as of 18:27, 5 April 2002

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There are two customary usages of the term:

The more academic usage refers to the design of a computer's underlying languaugelanguage - its "[[instruction set]]." This will include information such as whether the computer's processor can compute the product of two numbers without resorting to external memory. It will also include a nominal precision for the computer's computations.

The less formal usage refers to a description of the design of gross requirements for the varousvarious parts of a computer, especially speeds, and interconnection requirements.

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1. Cost

Generally, cost is held constant, determined by either system or commercial requirements, and speed and storage capacity are adjusted to meet the cost target.

2. Performance (speed)

Computer retailers describe the performance of their machines in terms of [[CPU]] [[Speed]] (in MHz or GHz). This refers to the cycles per second of the main clock (megahertz or MHz is millons, gigahertz or GHz is billions). It does not indicate the number of instructions. Some CPUs execute less than one instruction per clock. Some "super scalar[[superscalar]]" CPUs execute more than one instruction per clock.

Throughput is the absolute processing power of the computer system. In the most computer systems, throughput is limited to the speed of the slowest piece of hardware in use at a given time. This slowest piece might be input and output (I/O), the CPU, the memory chips themselves, or the connection (or "bus") between the memory, the CPU and the I/O. The limit most acceptable to users is the speed of the input, because the computer then seems infinitely fast. General-purpose computers like PCs usually maximize throughput to attempt to increase user satisfaction.