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Memory (ROM (Read Only Memory is a type of main memory because it is…
Memory
ROM
Read Only Memory is a type of main memory because it is directly accessed by the CPU. Like RAM, memory locations in ROM can be accessed in any order.
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ROM chips are usually located on the motherboard or printed circuit board such as a graphics card. They are not removable as they are soldered into the motherboard.
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Volatile Memory
Anything you are currently working on is stored in main memory. Main memory is almost always volatile, with the exception of ROM chips.
Volatile memory is cleared whenever the supply of power is lost. In contrast, non-volatile memory will continue to hold anything it was storing even if it is not receiving any power.
Secondary storage is always non-volatile, as the programs and data that are held there are meant to be kept long-term. This is why, while you might lose any files you are working on if power is cut, if you save them first those files are safe.
Volatile memory is a type of memory that loses its data once power to the memory chip is switched off or interrupted.
Volatile memory includes RAM, CPU registers and the cache.
RAM
RAM is used as main memory. It acts as a temporary store for program instructions and data. It can only store things temporarily because it is volatile.
It is useful as a temporary store because any data or instructions in RAM can be accessed in any order. This is why it is called Random Access Memory.
A RAM module is slotted into a socket on the motherboard. This is why it is fairly simple to change or upgrade RAM in a computer as you just swap out the memory module.
Virtual Memory
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Virtual memory is volatile. If the computer is turned off, the operating system loses track of what was kept where in virtual memory. The data is lost.
Less-used data is moved from RAM to virtual memory. Data that the CPU needs to use right now moves from virtual memory to RAM.
Main Memory
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Secondary Storage
Secondary storage is used for holding large amounts of data and programs long-term, but can only be accessed relatively slowly.
DRAM
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DRAM is commonly used for main memory because it is inexpensive. However, it needs to constantly receive a "refresh signal" to keep its capacitors charged, otherwise it will lose the data it is holding.
SRAM
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It is commonly used for the cache. This is because it is much faster to access than DRAM and it doesn't require a fresh signal.
How Much RAM?
Bytes..............Size
1204 Bytes.....1KB [kilobyte]
1204 KB.........1MB [megabyte]
1204 MB........1GB [gigabyte]
1204 GB........1TB [terabyte]
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