How a computer accesses instructions and data in memory.
When a computer executes a program, it needs to read instructions and data from memory. So, how does a computer find and properly access the instructions and data in memory?This involves the internal structure of a computer and a series of complex processes.
First, we need to understand the memory structure of a computer. A computer's memory is divided into several layers, from cache to main memory to disk storage. Of these memories, the computing core of the computer mainly accesses the cache and main memory.
The cache is the fastest piece of storage in a computer and is usually made up of static random access memory (SRAM). It sits between the compute core and the main memory and is used to store recently accessed instructions and data. Since the speed of the cache is very fast, the computer can read instructions and data from the cache very quickly, thus improving the efficiency of program execution.
If there are no required instructions or data in the cache, then the computer will need to read from the main memory. The main memory is usually made up of dynamic random access memory (DRAM), which is much larger than the cache but has a slower access speed. To speed up access, the main memory is typically read in blocks, which are typically 64 bytes in size.
So, how does a computer know where the instruction or data it needs to access is in the main memory?This involves the computer's address bus. The address bus is the bridge between the computing core and the main memory, and it is responsible for transmitting address information. When the arithmetic core needs to access the main memory, it sends an address signal through the address bus, which points to a specific location in the main memory. After receiving the address signal, the main memory transfers the corresponding block to the cache for use by the computing core.
In addition to the address bus, the data bus is also very important. The data bus is responsible for transferring the actual data between the compute core and the memory. When the arithmetic core reads instructions or data from the main memory, the data is transferred to the arithmetic core via the data bus. Similarly, when the arithmetic core needs to write data to the main memory, the data is transferred to the main memory via the data bus.
In addition to the main storage, disk storage is also an important part of the computer. Disk storage has a much larger capacity than primary storage, but it is slower to access. When the amount of data in the main storage exceeds a certain threshold, the computer automatically transfers some of the data to the disk storage. This saves space in the main memory while ensuring the normal operation of the program.
In general, computers use technologies such as caches, address buses, and data buses to quickly access instructions and data in memory. The use of these technologies can greatly improve the efficiency of program execution, allowing our computational tasks to be completed faster and more efficiently. At the same time, with the continuous development of technology, it is believed that the future of computers will be more intelligent and efficient.