Just when you thought those sly devils in the Product Development labs at the software companies were sitting back on the their laurels, they've come up with a whole new breed of programs that turn your personal computer into an alarm clock. This raises an intriguing question.

You may think the question I have in mind is "Why would I want to turn my $3,000 computer into a $9.95 alarm clock?" But nooooo.

I wouldn't want to raise that mischievious question because it leads to a lot of other dangerous thoughts that penetrate to the heart of our computer addiction: "Why would I want to turn my $3,000 computer into a $6.95 recipe file? Or an $8.95 Rolodex? Or a $3.95 desk calendar? Or an 89-cent notepad?"

I own programs that do all those things, and I like them). So I'm surely not going to challenge the basic utility of an alarm-clock program.

It's not hard to see how an alarm clock built into your computer could be useful. As a general proposition, if you don't have an alarm clock on your desk now, it makes sense to use the clock circuitry that's ticking away in your computer.

For precisely that reason, I wrote a simple BASIC program some time ago that will buzz an alarm and put a message on the screen when it's time to call the boss or file the story, or whatever. This is an IBM-PC version, but it should work on almost any computer with an internal clock and any version of BASIC that has the "TIME$" function:

10 Input "Alarm Time";A$

20 Input "Appointment";M$

30 CLS 40 If TIMEA$ then 60

50 Goto 40

60 Print "It's ";TIME$

70 Print M$

80 Beep 90

Goto 80

You "set the alarm" by typing in the time, complete with seconds (e.g. "11:30:00") and describing your appointment (e.g., "lunch with boss"). At the chosen moment, the machine will flash your appointment on the screen and beep an alarm. To stop it, press the CTRL-BREAK combination.

Of course, this BASIC routine works only if it's left alone to run. (Essentially, the program loops continuously around lines 40-50, checking the clock against the pre-set alarm time.) It won't work if you're running another BASIC program or using the computer for any other work.

The new alarm-clock software now on the market, in contrast, will not only work as a stand-alone alarm clock but can also be programmed to interrupt you at a pre-set time no matter what you are doing on the computer at the chosen moment.

So there is some sense after all in converting computer to alarm clock. I could appreciate an alarm that pops up on the screen as I'm polishing the words in a contract and warns me that the Express Mail window will close in 10 minutes. I can appreciate a function that interrupts a spreadsheet, or chess game, or whatever else I might be doing on the office computer, to remind me that it's time to meet the boss for lunch.

Some of these programs come as part of the new "accessory" software (for example, there's an alarm-clock function built into both Warner Software's $295 "Desk Organizer" and Polytron's $50 "PolyWindows"). Some are available as stand-alones: Bellsoft (2820 Northrup, Bellevue, WA. 98004) will send you its new "Pop-Up" Alarm Clock for $5 as a come-on to get you hooked on the whole "Pop-Up" series of accessory programs.

But the very existence of these programs raises an intriguing question. If you're using your computer as an alarm clock, doesn't that mean you don't dare turn it off? If you come to work at 8 a.m. and tell your alarm program to remind you of your 11 a.m., 3 p.m. and 5 p.m. meetings, don't you have to keep the machine on all day long?

Yes you do -- but then, you should probably do it anyway. I posed the question to my battery of technical gurus: Should you leave your computer on all day, even if you're not using it? With some dissent (you can never get these technical types to agree completely), the answer we got was a strong "Yes."

Leaving the computer on all day can't hurt it (unless you have an unreliable rural power supply with lots of spikes and surges), and the amount of electricity consumed is minute.

On the other hand, turning the machine on and off for each separate job conceivably could be harmful. There's not much that can harm the micro-electronic innards of a computer, but one possible hazard is a continuing series of temperature changes.

Every time you turn on your computer, the circuitry heats up a little. Every time you turn it off, the inside cools down. On the whole, it's probably better to spare your machine a lot of heating and cooling through the day. So turn it on once in the morning and leave the switch alone thereafter.

In summary, I think -- Whoops! I have to stop. The beeper just started beeping, and a message popped up on the screen reminding me of a heavy date. Right on time, too. This is the best $3,000 alarm clock I ever had.