THE BEGINNER'S PAGE
Tom R. Halfhill, Staff Editor
Starting this month, "The Beginner's Page" will be written by Tom R. Halfhill, editor of COMPUTE!. Halfhill's former column in COMPUTE!, "Questions Beginners Ask," will be incorporated into "The Beginner's Page."
A Column For Everybody
Welcome to the new Beginner's Page. A popular column in COMPUTE! since March 1981, "The Beginner's Page" was conceived as a way to introduce the main concepts of personal computing to beginners. But it's also a way to unite the users of the many different computers covered in COMPUTE!.
That's why "The Beginner's Page" will continue to involve every computer brand covered by COMPUTE!. It doesn't matter if you have a $79 Commodore VIC-20 or a $4000 IBM PC. If you have an interest in learning more about personal computing, that's enough. As always, we look forward to your questions, comments, and suggestions. We'll devote most of each month's column to a specific topic, and then conclude with an answer to a general-interest question, much like "Questions Beginners Ask." Sometimes the question will come from one reader's letter, and other times it will be culled from a number of letters asking pretty much the same thing. So keep the mail coming.
Emulators: An Impossible Dream?
Certain types of questions consistently recur in the mail we receive from readers. One such question has to do with emulators.
An emulator is an add-on accessory or adapter that lets a computer run programs designed for another computer which is normally incompatible. The concept of an emulator is fascinating, almost mesmerizing, especially for beginners. Imagine having access to the hundreds and even thousands of programs available for other computers. It seems that your software problems would be solved overnight.
Unfortunately, it's not that simple. True emulators are very rare indeed. If ever there was reason to observe the warning "Let the buyer beware," you should heed it when encountering a sales pitch for an emulator.
For instance, when the Commodore 64 first hit the market, there were all kinds of rumors about forthcoming Apple emulators. Several companies, supposedly, were preparing plug-in modules that would let Commodore 64 owners simply load an Apple program off a disk and type RUN. Some companies even advertised their Apple emulators in magazines. But they never materialized.
We received scores of letters from readers asking about these emulators, and we followed every lead. But each time we contacted the company involved, we got pretty much the same answer: "Available soon." Of course, "soon" stretched into "never."
At the time, the idea of an Apple emulator held great appeal for Commodore 64 owners because there wasn't much software for their brand-new computer. Now, two years later, there's a virtual glut of Commodore 64 software and the idea has lost some of its attraction. Even though the Apple has acquired a huge software library (estimated at 10,000 programs) after more than seven years on the market, the Commodore 64 software has all been written within the past two years and is generally more up to date. In fact, there are probably some Apple owners today who'd like to get their hands on a Commodore 64 emulator.
Over the years we've heard wishes, rumors, and announcements of other emulators, too: adapters to make Atari game machine cartridges compatible with Atari computers, or vice versa; a Commodore 64 emulator for the VIC-20; and even an IBM PC emulator for the Coleco Adam (actually announced by Coleco for tentative release in late 1984). But chances are you'll never see any of them. Or if you do, they'll scarcely be cost-effective.
Turning Mountains Into Prairies
There are two problems to overcome when designing an emulator: First, you have to exactly duplicate every hardware function of the computer you're trying to emulate (while avoiding patent- and copyright-infringement suits); and second, you have to match or exceed the performance and cost-effectiveness of the computer you're trying to emulate.
Let's tackle the first problem. It might seem that a Commodore 64 and an Apple lie, for instance, have a lot in common: Both have 64K of Random Access Memory (RAM), 16 colors, high-resolution graphics modes, a standard 40-column screen format, built-in Microsoft BASIC, and compatible central processing units (the eight-bit 6502/6510 microprocessor). But these details are superficial. Internally, the computers are completely different.
Both computers may have 64K of RAM, but the way it's laid out is so dissimilar that it's like comparing 64 acres of Kansas prairie with 64 acres of Colorado mountains. The color capabilities, graphics modes, methods of screen display, BASICs, and internal operating systems are likewise totally different.
There are ways around these incompatibilities, but then you run into the second problem. It's been said that any computer can emulate any other computer—as long as expense and performance are not considerations. In other words, you could bulldoze the Rocky Mountains to turn them into prairies, and dump the rocks onto the Kansas prairies to turn them into mountains, but is it worth the trouble?
Emulator = Computer
The only practical way to build an emulator is to shrink the first computer down to a box or module that plugs into the second computer. Usually it's not worth it, because you could simply buy the first computer for not much more than the emulator would cost. For instance, once at a computer show we saw an Atari VCS game machine emulator for the VIC-20. It really worked, because essentially it was an Atari VCS in a plug-in module. However, it cost $89.95, and Atari game machines at that time were selling for $99.95. So the emulator cost $10 less, but didn't come with a pair of joysticks, paddle controllers, or a free game cartridge as the VCS does.
Similarly, one Apple emulator that was announced for the Commodore 64 was to be priced at about $800. But at some discount dealers, you can buy an Apple He and a disk drive for not much more. Why buy the emulator?
For an emulator to be worthwhile, it should provide at least 90 percent compatibility at a price significantly less than what the other computer would cost. Even then you should balance the cost of the emulator against the benefits of running the other computer's software.
Admittedly, it would be nice if we could buy inexpensive emulators that would let us run software written for everybody else's computers, because then our choice of which computer to buy wouldn't be so difficult. It would also be nice if we could buy a Datsun or Renault and repair it with Chevrolet or Ford parts, and vice versa. But realistically, neither is likely to happen for a long time, and for many of the same reasons.
Questions Beginners Ask
Qln your September column ["Questions Beginners Ask"] you suggested using a bulk eraser or an audio recorder to erase tapes. There is a much simpler way that I have been using with my TRS-80 Color Computer, and there's no reason it shouldn't work with any other micro. Why not just rewind the tape, press PLAY and RECORD on the recorder, and type CLOAD "X"?
A Essentially this is identical to one of the methods I recommended—place the tape in an audio recorder, insert a null plug into the microphone jack or turn down the recording level, and press PLAY and RECORD. Either way, you're erasing the tape by recording silence over the previous material.
However, your method works only on TRS-80 computers; Commodore, Apple, TI, and IBM computers don't have a CLOAD command. Atari BASIC uses CLOAD, but if you try typing CLOAD and pressing RECORD and PLAY, the tape stops after a short while and the computer reports ERROR 138—device timeout. When the Atari detects no program on the tape, it stops the recorder motor. As mentioned in September's column, you can get around this by pressing RECORD and PLAY and entering POKE 54018,52 to start the motor, and POKE 54018,60 to stop the motor.
In any event, these methods are inefficient ways to erase a cassette. It takes a half-hour to erase a C-30, an hour to erase a C-60, etc. A bulk tape eraser does the same thing in a few seconds, and saves wear and tear on your recorder.