So what is a cache, anyway?

and why do I have to clean them out? and how do I do it? I asked this question over in Crick& Watson’s thread in ATMB, and only got the following reply from Triskadecamus:

intriguing, but I think a bit too low-tech.

I’m using IE5 on an iMac, if that’s relevant.


and the stars o’erhead were dancing heel to toe

For the purposes of this discussion, a cache is space on your hard drive, where the browser stores images and text from web pages. For instance the straight dope logo, the little light bulbs, the folders, etc. By storing them on the drive, the browser can build the page faster, since it doesn’t have to go across the web to grab the image.
To empty the cache (at least in IE5 on a pc) goto Tools > Internet Options > Temporary Internet Files. This will let you delete the cache, and set how much disk space is used for the cache.
How this helps.

Your specific case was covered by docandjean. However, if you’re looking for a more general definition: a “cache” (in computer terms) is a temporary storage area which is quick to access where a small amount of information from a place which is slow to access is placed, because it is likely to be needed again, and you don’t want to wait to get it from the slow location. For web browsers, that means putting information (such as image files) on your hard drive, which can be read much faster than pulling them over the network. For microprocessors, a cache is used to store data which is taken from main memory (DRAM), because accessing the cache (usually inside to nearby the CPU) is much faster than accessing main memory (which usually is slow, and requires the data to flow though several intervening chips). These are the two places you are most likely to encounter this term.

If I had thought for one moment that my smart assed joke was going to be your only answer, I wouldn’t have made it. Sorry.

In computer systems, some things are very fast, and some things are blindingly fast, and some other things are unbelievably fast. When you have the situation that an unbelievably fast thing has to wait until a very fast thing happens, then engineers usually build a thing called a cashe.

The cashe is a storage for data which is provided by the very fast thing, and is, itself an unbelievably fast thing, that way the other unbelievably fast thing only has to wait once for the very fast thing. After that, it uses the data stored in the cash, instead of accessing the very fast thing. It works really well when the data is the same every time, and is merely being read, and not written to.

Here is an example. AOL has millions of requests for data every second, all day long. The have huge memory structures built to hold web pages which they have just downloaded from the WWW. If a second request for that URL comes in during a relatively short time period, the data from the first request is still in RAM (or on the AOL server’s hard drive.) Getting it from RAM is a whole lot faster than retransmitting it from Chicago, to Reston, and then to you. If you were just looking at nekkid girls, you would be pleased not to have to wait. If you are keeping up with a fast moving message board, you are pissed, because the cached copy is not current, even by human time standards.

If you press the “refresh” button on your IE5 tool bar, at the top of your screen, IE5 will specifically request that the information be updated from the original source, rather than a cache on your computer, or on AOL.

<P ALIGN=“CENTER”>           Tris </P><HR>

<FONT FACE=“Webdings” SIZE=5 COLOR="#ff2400"> ** - ** </FONT> </P>

Tris,

not to worry - i had a good chuckle - that’s why I moved it here, so others could appreciate it as well.


and the stars o’erhead were dancing heel to toe