25 lines
1 KiB
Markdown
25 lines
1 KiB
Markdown
---
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tags: [memory]
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created: Friday, July 12, 2024
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---
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# What is memory ?
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> A CPU is just an operator on memory. It reads its instructions and data from
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> the memory and writes back out to the memory. (Ward 2021)
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When a [CPU](CPU_architecture.md) executes a program, it needs a place to store
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the program's **instructions** and **related data**. This is the role of memory.
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The data that comprises a program is a series of bits. The basic unit of memory
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storage is a **memory cell**: a circuit that can store a single bit.
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[RAM](./DRAM_and_SRAM_memory.md) memory is _volatile_ : the memory is only
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retained whilst the computer has a power supply and is wiped when the computer
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is rebooted. This contrasts with the memory of the harddisk which is
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non-volatile and is retained after a reboot.
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Programs that are executing are loaded into memory because the chips that
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comprise memory can read and store data much faster than the harddisk. It would
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be possible to run a program from the harddisk but it would be 500 - 1000 times
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slower than memory.
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