Everybody's Doing It - Mac in a DOS World

By Sean McMains, Microcomputer Consultant mcmains@unt.edu

You want a new computer. You've decided that the Macintosh is the machine on which you work the best, so you tell your boss that;s what you want. You explain the graphic user interface is very polished and that it helps minimize the learning curve for new applications, allowing you to spend less timedigging in manuals and more at work. You tell him about the built-in multimedia features. Everything is going along smoothly until the boss asks the dreaded question: "Is it DOS compatible?" You hem and haw for a few moments, look down at your shoes, and finally look him in the eye and say "Why, yes. Yes it is."

When the Macintosh was first introduced, it was perceived as a toy computer. Not only did it have little pictures and cute graphics that were out of place on "serious" computers, but it didn't work with anything else on the market. As the PC Compatible market boomed and the Mac line became more capable and powerful, this rift was widened by Apple's continued determination to keep their system software in-house and unable to be reproduced by anyone. As a result, noone was able to develop clones of the Macintosh in the same way that had been done for the IBM machines, and the gulf between the two platforms remained unbridged.

Macintosh and DOS Compatibility

This is what we in the computer industry like to call a "third party opportunity." Seeing that there might be quite a demand for machines that could handle DOS software as well as Macintosh software, several companies delevloped products that wuld allow one to do just that. The two biggest players in this arena up until recently have been Orange Micro and Insignia solutions.

These two companies have developed different approaches to running DOS software on a Macintosh. Orange Micros's solution uses a coprocessor, while Insignia uses something called a "software emulation." Each of these technologies has its advantages and disadvantages, and might be used for different applications.

Basically what Orange Micro has done is to have designed a board that is essentially a PC-compatible computer on a card that sits inside the Mac and runs the DOS software while the Mac's CPU continues to take care of Mac software . The advantage to this arrangement is that it essentially provides the user with two complete computers in one box, allowing one to run different kinds of programs simultaneously and without one environment affecting the performance of the other. When performance is of primary importance, this makes for an excellent solution.

Insignia has taken a very different route with their product. They have basically written a program to pretend that it's a DOS machine, and to fool the DOS software into believing it as well. The advantage of this approach is that Insignia's software can tell DOS programs anything it wants about the machine configuration, and as long as it provides the necessary illusion, everything will work fine. The practical result of this is that one can use the Macintosh's mouse, serial ports, networking capabilities, etc., and all seem to the DOS program to be exactly what it would expect. This approach is also much cheaper that the coprocessor approach, as there's no extra hardware to pay for.

The Apple Solution

Recently, Apple has made this market a bit more interesting by introducing a product of their own, the Quadra 610 DOS compatible. This is a Macintosh Quadra with a built-in coprocessor to allow it to run both DOS and Macintosh software. It is somewhat less capable than Orange Micro's solution, but for the $500 over what a Quadra would normally cost, it's hard to argue with the prce.

One of the most exciting developments in this area that will occur soon is the introduction of the PowerPC based Macintosh. Up to now, all Macintoshes run on the 68000 series of microcomputers. In April, Apple will begin migrating the Macintosh line over to a new kind of processor, called the PowerPC, which promises to provide perfomrance increases of 200%-400% over the current chips. In addition, work is well underway that will allow these machines to run many different operating systems, including DOS, Macintosh, Windows NT, UNIX, and others, resulting in one box that will run just about any software that's out there. The PowerPC Macintoshes will use software emulation to do their magic, but since their chips are so much faster than the existing ones, they should be able to provide performance comparable to the older processors when running code written specifically for them. Of course, code written specifically for the PowerPC will race past that which has to rn in emulation mode.

Though historically the worlds of DOS and Mac have been entirely seperate, the major vendors have finally begun to acknowledge that most environments are not solely Macintosh or solely PCs, but a combination of the two. This has opened the door to an unprecedented degree of interoperability between the two platforms, and has finally allowed us to have our Mac and PC as well.


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