At the very back of one of the handful of magazines dealing with micro computing that I receive each month is the Apple personal computer's equivalent of the hit parade.

The 30 best-selling software packages listed each month range from word processing systems, filing aids and electronic spreadsheets to games and adventures. But, regardless of their genre, the message is the same: for an item to make it there is to break into the big time, much like a rock album that has hit the charts.

Software is the heart of a personal computer.

In fact, it can end up making a computer company profitable -- the electronic version of the tail wagging the dog.

There are some who believe that Apple owes its dominant position in the marketplace today less to its design excellence than to the fact that VisiCalc -- the most popular piece of commercial software -- was first designed to run only on Apples.

What the VisiCalc program did was transform Apple personal computers into electronic spreadsheets easily operated by small businessmen with no computer expertise. Suddenly, they had an affordable computing system whereby they could type in the numbers, press a button and almost instantly have calculations that before would have taken them several days to figure out.

Not only that, but VisiCalc, which was created by Software Arts of Cambridge, Mass., gave small businessmen the power to analyze hypothetical cases quickly. They simply plugged in "what if" numbers in place of the actual figures, getting answers in seconds.

It was a sensation that until recently was No. 1 on the software hit chart (now it's No. 2). VisiCalc and its clones are now compatible with just about every personal computer available. But the name VisiCalc remains all-powerful, so much so that even IBM, the giant of the computer industry, was unwilling to introduce its own personal computer without first arranging for a compatible VisiCalc program to be on the market.

Such name recognition has made VisiCalc the top software seller in the short history of personal computers. Since 1978, when it was conceived by a brainy New England graduate student, VisiCalc has sold between 350,000 and 400,000 copies worldwide.

What this means to you is simple. Because it is unlikely that you will ever learn enough of the Pascal or BASIC or Fortran computer languages to break into the program-development phase yourself, you're probably going to be at the mercy of the marketplace when it comes to software.

The most important thing is to know what you want your computer to do.

Find a salesman you feel comfortable with, then have him demonstrate all the software that might conceivably help your computer accomplish whatever it is you want done. Don't buy the cheapest computer just because it's the cheapest, nor the most expensive because it's the reputed "Cadillac" of personal computers.

You might consider a personal computer that has a broad selection of software already available. There will be a large sofware library to shop from, and it is a good indication that there are a lot of computers like yours already out there