Memory (Temporary)

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Temporary Memory is often called RAM (a kind of temporary memory). A computers memory works a little like a persons memory. We have two types of memory; short term and long term, or in computerese this is called temporary and permanent storage (memory).

Some people seem confused about many computer terms and concepts dealing with a computers "memory". The irony is the same people understand the exact same concepts when applied to people or human brains - but when applied to computer-brains, they get befuddled. But it is really very simple.

Computers have a few "parts" to their brains. They have the main part that does the "thinking" or processing. This is the "Central Processor Unit" or CPU. It is just a computer chip that takes instructions from "memory" and executes those instructions, and saves results to "memory". So memory is critical to understanding computers.

Short term or temporary memory is for things we are working on at the moment. In humans, if you don't keep repeating a phone number or name someone just told you, then you might forget it, because it is in "short term" memory. For computers, this is the programs or data that you're working on - if you turn off the computers power (without saving) then it will be gone (forgotten). This type of memory in computers is usually called RAM.

RAM stands for "Random Access Memory". The reason is because some earlier types of computer memory were "sequential" like a cassette or video tape. To get to some part of memory (say a song a cassette tape or show on the VCR), you have to go through or past all the other stuff - like fast forward or rewind. You can sort of scan faster, but you're still going sequentially past it. Later, we created better forms of memory that allow you to go anywhere "at random"; like a compact disc, DVD or record (for those of you old enough to remember those). Instead of having to fast-forward to the song/video you want, you can just skip ahead to it. It is non-sequential access, or "Random Access".

In computers there are many types of RAM, with all sorts of acronyms and terms; DynamicRAM (DRAM) or StaticRAM (SRAM), or how the RAM is accessed: SDRAM, FPM (fast page), EDO or HPM and so on. Those terms just meant how they worked at a detailed level; like how often they have to "repeat" the phone number to themselves (refresh) or else they forget the number (just like you might). There are also some terms like the speed of the RAM, like 60ns, 10ns (nanosecond, or billionths of a second), and so on. And still other RAM terms are just the form factor that the RAM comes packaged in - like RIMM, DIMM, SIMM, SO-DIMM; this just means what the connector/package looks like and how it plugs in to the computer. But all these complex terms are just types of RAM.

So if you hear anything about "RAM", you'll know what it is for. It is a computers "short-term" or "temporary" memory. It is where a computer puts things that it is working on or things it just "learned". Next article I'll go more into other types of memory.

Long term memory (or permanent memory) is for things that we want to remember for long periods of time. In computers, we do this by "saving" chunks of memory (files or programs) to some device that is meant to provide our permanent memory.

Written 2002.03.11