What does the width of the address bus have the greatest impact on in a microcomputer hardware system?

The width of the address bus has the greatest impact on the "size of storage space directly accessible to the CPU". The address bus is specially used to transmit addresses, and the width of the address bus determines the physical address space that the CPU can access. Simply put, it is how much memory the CPU can use. Therefore, the address bus width affects the size of the storage space that the CPU can access. maximum.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

The width (number of bits) of the address bus in the microcomputer hardware system has the greatest impact on the "size of storage space that the CPU can directly access".

The Address Bus (also known as: Address Bus) is used by the CPU or units with DMA capabilities to communicate that these units want to access (read/write) computer memory The physical address of the component/place.

The address bus AB is specially used to transmit addresses. Since the address can only be transmitted from the CPU to the external memory or I/O port, the address bus is always one-way three-state, which is different from the data bus.

The address bus width determines the physical address space that the CPU can access. Simply put, it is how much memory the CPU can use.

For example, the address bus of an 8-bit microcomputer is 16 bits, and its maximum addressable space is 2^16=64KB. The address bus of a 16-bit microcomputer is 20 bits, and its addressable space is 20 bits. is 2^20=1MB. Generally speaking, if the address bus is n bits, the addressable space is 2^n bits.

The width of the address bus varies with the size of the addressable memory element and determines how much memory can be accessed.

For example: a 16-bit width address bus (commonly used in 8-bit processors in the 1970s and early 1980s) reaches 2 to the 16th power = 65536 = 64 KB of memory address, and a 32-bit unit address bus (usually in a PC processor like today's 2004) can address 4,294,967,296 = 4 GB of addresses. But now many computer memories are larger than 4G (windows XP x32-bit system can only recognize a maximum of 3.29G, so if you want to use more than 4G of memory, you must use windows x64-bit system). Therefore, the current mainstream computers are all 64-bit processors, which means that they can address 2^64=16X10^18=16EB addresses. This number will not be used up for a long time.

In most microcomputers, addressable components are 8-bit "bytes" (so "K" in this case is equivalent to "KB" or kilobyte), and many computers Examples include larger data blocks as their smallest physically addressable components, such as the CPUs of mainframes, supercomputers, and some workstations.

For more related knowledge, please visit the FAQ column!

The above is the detailed content of What does the width of the address bus have the greatest impact on in a microcomputer hardware system?. For more information, please follow other related articles on the PHP Chinese website!