First choose software to perform tasks you want, then buy computer

A microcomputer without software is like a record player without records. Software is a general term, meaning the programs, or instruction sets, that allow computers to do everything from writing to drawing pictures to performing complex financial calculations.

Unfortunately the current state of the industry makes buying personal computers and software far more difficult than picking out a record player and records. While you can buy almost any turntable with the assurance that it will play your favorite disks, the same cannot be said for computer hardware and software.

The microcomputer business is complicated by a lack of standards, much as if each record-player manufacturer designed its turntables to spin at a different speed and hold different-size records. To work, programs must be tailored to specific computer models.

The situation is further complicated by differences in systems software. Each microcomputer contains a program called an operating system. This controls the way the various pieces of the computer system communicate with each other. Systems software regulates how information from the keyboard is processed, drives the video display, reads and writes information to and from the computer's floppy-disk storage, and runs the printer.

The same computer will run differently with different operating systems. By far the most popular operating system is called CP/M and is the product of Digital Research Inc., a California-based company. This is a somewhat arbitrary and limited system. But because of its popularity, more applications programs - programs that do such specific tasks as bookkeeping or text editing - have been written for CP/M than for any other operating system.

Computer consultants and columnists routinely advise buyers to shop first for the software that best fits their needs, and secondly to pick from the computers that will run the programs they prefer. This also makes sense because high-quality software can easily add up to more than the total cost of the computer itself.

The first step in selecting a computer system - both hardware and software - is to decide exactly what you want to use it for. ''It may seem simplistic and obvious to say you need to decide just what you want the computer to do,'' write Jerry Willis and Merl Miller, in their introductory book, ''Computers for People'' (Dilthium Press, Beaverton, Ore. $7.95). ''You would probably be surprised, though, at the number of people who buy a computer with only a vague idea of exactly how they will use it.''

Although programs now exist for over 1,500 different types of applications, today's home and personal computers generally have a relatively limited repertoire. The major uses include writing, filing, financial planning and record keeping, games, accessing electronic-information systems, and personal education.

The cost of computer software varies greatly. A number of electronic bulletin boards offer ''freeware'' of various sorts for the cost of copying the program. Commercial business-accounting packages, at the other extreme, can run into thousands of dollars.

Generally the price of programs is pegged to the cost of the computers that run them. Just as the microcomputer market is breaking up into three categories - home computers for $100 to $1,500; personal computers for $1,500 to $5,000; and small-business computers for $5,000 to $10,000 - so is the associated software market. Thus, a competent word-processing program for a $300 home computer will range from $50 to $150. For a more expensive personal or business system, the cost of a similar, but more sophisticated, package will run closer to $500.

One practice that began with the manufacturers of portable computers and appears to be catching on throughout the industry is ''software bundling,'' or including a set of software with the purchase of a computer. An example of this is Morrow Designs, which has recently been advertising a computer for $1,790 with over $2,200 worth of software.

Like the price, software quality is variable. Quality differences tend to be greatest in the ease with which a program performs a given task and in how forgiving it is of operator error. A top-quality program will incorporate mnemonic systems to make it easier to remember the keystrokes needed to get it to work. It will recognize and intercept potential operator mistakes that can lead to information loss in the computer's memory. And it will have an easily accessible ''help menu,'' which lists and defines commands on the screen.

Because computers are so flexible, different programs can use remarkably varied and sometimes extremely arbitrary methods to accomplish a given task. This means that intuition is of little help in figuring out how a program should work, even for the experienced user. This makes the quality of the instruction manuals of critical importance.

A useful rule of thumb in shopping for software is to look over the instruction manuals carefully and rule out programs with inadequate documentation. A good manual will have a tutorial section that takes the user step by step through specific examples that show how the program works. It will have a glossary of all its commands. And it will have an index.

There are literally thousands of programs now on the market. Unless you are shopping for a relatively expensive business computer, don't expect computer sales people to spend much time trying to teach you the basics. A novice has the choice of putting himself blindly in a salesperson's hands, turning to a knowledgeable friend for advice, or educating himself before buying a system.

One of the best sources of software reviews is InfoWorld, a news weekly for microcomputer users that is available at newsstands and bookstores. Each issue has at least six software reviews - and for $3.95, InfoWorld will send you their Report Card, a detailed evaluation of over 50 of the most popular software packages and brief summaries of over 250 others.

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