In a computer system, which bus structure is used is often correct The performance of the computer system has a great impact. The following three aspects will discuss this impact
- Maximum storage capacity At first glance, The maximum storage capacity of a computer system seems to have nothing to do with the bus, but in fact the bus structure will also have a certain impact on the maximum storage capacity. For example, in a single-bus system, the difference between access to main memory and peripherals is only The addresses on the bus are different. For this reason, certain addresses must be reserved for peripheral devices. Because some addresses must be used for peripheral devices, in a single bus system, the maximum main memory capacity must be less than what is possible determined by the word length of the computer The total number of addresses. In a dual-bus system, the judgment of access to the main memory and peripherals is to use their respective instruction opcodes. Since the main memory address and the peripheral address appear on different buses, the storage capacity will not be affected by the peripherals. How much equipment is affected.
- command system The bus must have a different instruction system. This is because the opcode specifies which bus to use, so in a dual-bus system, there are different instructions for memory access and input/output operations. On the other hand, in a single-bus system In, access to main memory and 1/O transfer can use the same opcode, or use the same command, but they use different addresses.
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- ThroughputThe throughput of a computer system refers to the rate of information flowing into, processing and flowing out of the system It depends on how quickly information can be entered into memory, how quickly the CPU can fetch instructions, how quickly data can be retrieved from or stored in memory, and how quickly the results can be sent from memory to a peripheral device. These steps Each step in the process is related to the main memory. Therefore, the system throughput mainly depends on the access cycle of the main memory.
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The performance of the bus determines the speed and efficiency of data transmission in the computer and thus affects the performance of the computer The bus connection method causes the bus to become the bottleneck of the computer transmission rate. Therefore, the computer can be improved by optimizing the bus structure performance. Bus is an information transmission line that connects multiple components. It is a transmission medium shared by each component. The more buses, the more convenient the information exchange between components, but the realization of its ports It will become more complicated. The bus structure affects the performance of the computer and the data transfer rate. The more buses are not the better, which may bring about cost and technical problems. Reasonable bus structure design can improve computer performance. Premise: The bus is characterized by a public transmission channel of information, and only one pair of input and output devices can operate at any one time.
Result 1: If the structure of the bus is based on the CPU, then the data transmission must pass through the CPU, which will cause the CPU to be busy and affect the computer’s computing speed, so the bus should be based on memory
Result 2: Because the bus can only have one pair of input and output, the single bus determines that the current computer can only have one pair of input and output. To achieve multiple pairs of input and output at the same time, it must be designed into a multi-bus structure
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