Computers have apparently been around for a really long time, depending on what kind of computers we are talking about.
Many anthropoligists, for example, consider Stonehenge to be an example of a computer. It would not be the kind of computer you use to surf the web, but we think it was used in computing, as it were, the positions of the sun, moon, stars, and so forth.
What? You ask, "Wouldn't it be more accurate to say, "record the positions"?
Well, yes and no. The positions change by season and year, and the construction of stonehenge, according to many anthropologists, allowed the changes to be predicted. That involves calculation. (I leave looking this up on the web or in your favorite encyclopedia as an exercise for the reader. I don't want to distract you or myself with tons of links, and it's easy enough to look up "Stonehenge" on the web or in physical books.)
So, you ask, shouldn't we then call it a calculator instead?
Well, that is an example of how the definition of "computer" has changed over the course of history, and of what underlies my motivation to write this.
When I or you or an anthropologist or your lawyer or my accountant say, "computer", we all mean different things.
When I was a teenager, the handbook for the Boy Scout Computers merit badge contained one definition. It said, as best as I remember, that a computer consisted of the combination of a processing device with input and output devices. And that was a really broad definition.
The working definition for the merit badge has changed. I don't have the current requirements handbook, I suppose I should check with my brother. But for a while, at least, it pretty much tracked the current definition in the (information technology) industry.
I think even the information technology industry has backed off the definition that seem to have been most convenient for it during the late 80s, 90s, and early 00s -- requiring some sort of working store (RAM), persistent store (disk drive), user input device (keyboard), and user output device (screen/monitor), in addition to the central processing unit. I think I even recall a trend to require a certain minimum amount of both RAM and disk. And one prominent computer company was bound and determined that their CPU would become the only CPU recognized. And all other computing devices were to be relegated to peripheral status.
(I really should dig up the articles that were most blatantly full of this kind of attitude from various industry magazines, from Byte to the ACM journals. If someone wants to pay me to turn this into a real book, I will.)
A quick search of the web (such as "definition of computer") shows that reason has been somewhat restored. Even "personal computer" is defined a bit more broadly, recognizing that setting arbitrary boundaries between the PDA, the portable phone, personal computers, tablets, etc., is more of an exercise in marketing, and not really as useful to those who use them.
Okay, now let's dig in a little deeper.: