When I bought my Apple II Plus back in 1981, I couldn't have told you the difference between a 40-column and 80-column screen.

I sure can today. And not only that, but I can also tell you that the advantages of 80 columns over 40 is something anyone shopping for a new or used personal computer ought to consider, especially if they're interested in using it as a word processor.

What those figures tell you is how many characters--that is, letters and/or numbers--your computer can get your television or video monitor to display from left to right on its screen. The term "column" means simply that each one of those characters appearing from left to right represents a column that falls from the top of your screen to its bottom.

Forty columns means that a maximum of 40 vertical columns of characters will appear from left to right on your screen. Eighty columns means twice as many columns will appear.

Why care?

If you expect you'll just be playing games on your computer, running educational programs, or doing some minor programming, it's not all that important. Virtually all games and educational programs now are written for 40-column screens. As for programming, some programmers prefer fewer characters on the screen because they think it keeps things less confusing.

But if you think you'll also be running some business programs and maybe writing a term paper or two, it's a toss-up between going for 40 or 80 columns. You can opt to save money now--but end up paying more later.

If you plan on using your computer almost entirely for word processing, however, screen-width capability becomes very important. It boils down to the fact that, even though you're not using a typewriter, the typical typewritten page has between 60 and 80 characters on each line.

With that in mind, try to imagine the difficulty you'd have in visualizing what that business letter you're writing on your computer will look like when it's finally printed out at 80 columns when all you can see on the screen as you write is a letter 40 columns wide.

More and more mid-range computers are coming with 80 columns as standard: the IBM, Zenith, the Apple III, for instance. Of that mid-range group, only the Apple II Plus--my computer--does not come with 80 columns. But as I write, Apple is introducing a new machine that will replace the Plus called the Apple IIe. While it, too, comes with but 40-column capability, it is modified so that for a relatively modest fee (about $100), a bit of hardware can be added inside that will give it 80 columns.

But if you fall into that middle range where it's a toss-up choice between 40 and 80 columns, you ought to consider that it can be expensive to upgrade a machine later from 40 to 80 columns. In my case, the hardware to boost my Apple II Plus to 80 columns can cost upwards of $350.

On top of that, shifting from 40 to 80 columns won't help my current word-processing program. It will continue to work at 40 columns despite the shift to 80-columns capacity. That means I'll have to spend an additional $150 to $250 to buy a word-processing program that can make full use of the 80 columns.

As the commercial says, "You can pay the man now--or pay him later."