What memory cannot be directly accessed by the CPU?

The memory that the CPU cannot directly access is: external memory (memory independent of the computer's memory and the CPU's cache). The reason why direct access is not possible: The CPU is fast, but the external memory is slow. If the CPU is allowed to access the external memory, the CPU will waste a lot of time waiting for the return data from the external memory.

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

The memory that the CPU cannot directly access is: external memory. The memory that the CPU can directly access is: internal memory (memory).

Because the CPU is fast and the external memory is slow, if the CPU is allowed to access the external memory, the CPU will waste a lot of time waiting for the return data from the external memory. The read and write speed of memory is much higher than that of external memory, so data on storage media such as hard disks must be transferred to memory before it can be accessed.

Memory is the bridge between external memory and CPU. All programs in the computer run in memory.

The function of memory is to temporarily store calculation data in the CPU and data exchanged with external memories such as hard disks. As long as the computer is running, the operating system will transfer the data that needs to be calculated from the memory to the CPU for calculation. When the operation is completed, the CPU transmits the results, and the operation of the memory also determines the stable operation of the computer.

Extended information:

External storage refers to storage other than computer memory and CPU cache. This type of storage can generally still save data after a power outage. Common external memories include hard disks, floppy disks, optical disks, U disks, etc.

The biggest advantage of external memory is its liquidity. Through external memory, we can easily transfer the data stored in it to another device. This provides great convenience to our work and life.

Like mobile phones, external memory is a must-have item for professionals and students. However, compared with internal memory, although external memory has the advantages of being cheap and easy to carry, it also has some disadvantages.

For example, in terms of data transmission speed, because the operation of external memory mainly relies on mechanical components, the gap between external memory and internal memory is relatively large. There is also a big gap in the data transfer speed between external memories at different price points and different qualities.

The memory size of external storage devices on the market already includes mobile hard drives that are several T taller. It can fully meet the needs of life and work. For those who do not have such large capacity requirements, you can choose a smaller capacity USB flash drive, which generally has 16G of memory. And the size is smaller than a hard drive, and there are many shapes to choose from.

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