01What Exactly Is Memory?

The English name for memory is RAM (Random Access Memory). You can first understand it as a computer's high-speed workbench.

Programs and data that the computer is currently using are usually placed in memory first, so the CPU can access them more quickly and continue working.

Hard Drive / SSD

Like a bookshelf or warehouse

Long-term storage for many things

Memory

Like a desk currently in use

For things being used right now

02Why Do Programs Need to Enter Memory First?

Suppose you want to open a drawing program. This program is originally saved long-term on an SSD. When you open it, the computer prepares the program content and data needed for the current session in memory.

1 SSD Storage Device

Program Saved on SSD

Still there after shutdown

2

Enters Memory When Opened

Prepares content currently needed

3 CPU Processor

CPU Accesses

Reads instructions and data and executes them

03What's the Difference Between Memory and Hard Drives?

Many people new to computers confuse "memory" with "hard drive space." They can both store data, but their purposes are completely different.

Memory RAM

  • Very fast
  • Mainly stores data currently in use
  • Capacity usually smaller than hard drives
  • Content usually disappears after power off

Hard Drive / SSD

  • Usually slower than memory
  • Responsible for long-term file and program storage
  • Usually larger capacity
  • Data remains after power off

Simple memory aid: Memory looks at "what's being used now," hard drives look at "what's stored long-term."

04How Do CPU and Memory Work Together?

In the previous article, we learned that the CPU continuously executes instructions in programs. These instructions and the data that needs to be processed often need to be retrieved from memory.

Memory

Stores instructions and data

Instructions / Data ⇄ Results
CPU Chip

CPU

Executes and processes

Example: Calculating 6 + 4

Memory has numbers 6 and 4 → CPU executes addition → Result 10 can be placed back in memory

Real CPUs also have smaller, faster storage structures like registers and caches. We'll learn about these as we continue studying.

05What Happens When There's Not Enough Memory?

Memory is like a desktop. When the desktop is large, you can spread out more books, notebooks, and materials at the same time; When the desktop is too small, you have to constantly put things away and take them out again.

Relatively Sufficient Memory

Data from multiple programs can be placed relatively smoothly on the "workbench."

Memory Almost Full

The computer needs to more frequently make space and swap data, operations may slow down.

06After Shutdown, Where Does the Content in Memory Go?

RAM in typical computers belongs to volatile memory: After power is cut, the temporarily stored content usually doesn't remain.

When Computer Is On

Memory stores programs and data currently in use.

After Shutdown and Power Off

This temporary content usually disappears.

What You've Learned

  • Memory RAM can be understood as a computer's high-speed workbench.
  • Programs that are running and data being processed are usually placed in memory.
  • Hard drives / SSDs are responsible for long-term storage, while memory is mainly responsible for "what's currently being used."
  • CPU frequently exchanges instructions, data, and results with memory.
  • When memory is insufficient, the computer may need to make space more frequently, thus slowing down.
  • Regular RAM content usually disappears after power off, so important files should be saved to storage devices.

Next Question: Since the content in memory disappears after power off, why can photos, programs, and documents still be saved long-term? Next article: Where Do Hard Drives Hide Data?