This past week Joe Stoddard the outstanding moderator of the Journal of Light Construction Computer Solutions Forum in response to a forum members question regarding Adding Memory wrote this great explanation of how a computer works:
Here’s how I explain CPU / RAM / Hard Drive (HDD).
Think of the computer in terms of your workshop. The Hard Drive (HDD) is your storage space (Cabinets, lumber racks, etc). The CPU (Processor) is the power tools you’re going to use to do work with your project (computer files)… and RAM (Random Access Memory) is your workbench where you put stuff to work on it. Hard drives are actual spinning platters with magnetic material on them (like the strip on a credit card) – they’re mechanical, and slow compared to solid state memory.
The way it works – Computers “read” information from the hard drive (lumber rack) and load it into RAM (put it on the workbench) in order to perform work on it with the CPU (Power tools). When done working on it, the data is ‘written’ back to the hard drive for permanent storage (put back on the lumber rack).
The amount of RAM (Random Access Memory) determines how much stuff you can pull down from the hard drive for the CPU to work on at a given time. Pretend instead of running Word or playing a computer game, you’re sanding cabinet doors. Lots of RAM means you can get all 20 doors on your workbench at a time and sand them all at once — vs. being low on RAM, which would be like having it sand one door at a time, walk across the shop, put it away, grab the next one, and walk back over to the workbench. Much, much slower.
So, you want lots of disk space so you can store a lot of stuff… lots of RAM so you can put a lot of work on the workbench at a time….. and a fast CPU so you can get things done as quickly as possible.
Of course, it’s not quite that simple – in addition to being able to store lots of stuff, you also need lots of free space on your hard drive , because in certain circumstances Windows will use that space like it’s even more RAM. This space goes by the moniker the “swap file” / “virtual memory” / “page file” / “temp file” etc. But bottom line, if there’s not enough free space on your disk for that usage, it’ll also kill your system performance as much or more than not enough physical RAM.
Hope that helps