Comparing IBM-PCs against Apple Macintosh computers

Comparing IBM-PCs against Apple Macintosh computers

(Written for LSU Criterion, 1/25/99)

I was asked to write an article about one of the longest standing debates in the personal computing industry: Which computer system --IBM compatible or Apple Macintosh-- is better? Which system is faster? Which system meets my needs? Which system should I buy?

With exception to historical facts, opinions expressed here are not necessarily those of the Department of Computer Information Services or La Sierra University.

To understand the differences between IBM-compatibles and Apple Macintosh computers, it is probably best to highlight some historical facts. IBM compatibles are so called because the Read Only Memory Basic Input Output System (ROM-BIOS) was licensed to many manufacturers, who had the right to engineer, build, and sell systems that were compatible to machines originally made by IBM. For most of its existence, Apple decided to keep the right to design, manufacture, and sell Macintosh ROM from other companies.

These critical decisions made in the early years of the personal computing industry, resulted in many manufacturers building and designing IBM-compatible hardware, while driving down production and manufacturing costs as they strived to out-do their competitor's efforts. On the Apple Macintosh camp, not licensing the ROM to other manufacturers resulted in fewer hardware manufacturers, and thus fewer competitors to lower the cost of manufacturing hardware.

IBM had been manufacturing mainframes for several years, and they believed that personal computers could be engineered with interfaces similar to mainframe computers. So it was no surprise that IBM expected a command-line driven interface when it asked Microsoft to develop an operating system for its personal computer (an operating system serves as the go-between for your computer program and the computer itself).

In 1981, Microsoft released its version 1.0 of the Disk Operating System (DOS). The emphasis of "disk" is probably due to the fact that most computers of the time used tapes to load operating systems. Because most computer professionals --and those we affectionately call "nerds"-- were familiar with the command-line interface, few saw the need for developing a better interface. Relying on IBM's good name, big corporations bought thousands of personal computers to run word-processors (WordPerfect), and spreadsheet programs (Lotus 1-2-3).

After Apple introduced the Graphical User Interface (GUI), Microsoft made many efforts to create a GUI for its operating system; today, we now know this product as Windows. Due to the large number of programs written under DOS, Microsoft --and Central Processing Unit (CPU) manufacturer Intel-- had to ensure that future versions of its operating systems and hardware, had to be compatible with "legacy" (those really old DOS) programs.

The need to maintain backward compatibility with legacy programs is one of Windows' biggest design dilemmas. For example, while the 640K memory barrier has been broken in later versions of Windows and DOS, many older programs expect the memory barrier; while Windows has provided the ability for multiple programs to run at the same time (multi-tasking), some legacy programs communicate directly with the computer hardware expecting to be the only program running on the computer.

The first Macintosh appeared in January of 1984, poised to unseat IBM as leader in the personal computing market. Apple Macintosh was designed as a GUI computer from the beginning; this meant that people interacted with the computer by using the mouse to click and drag on objects such as icons and windows. Macintosh computers were Plug-And-Play from the beginning; setting up a network of Macintosh computers, and connecting peripherals such as printers, hard drives, scanners, CD-ROM drives, have always been about as easy as connecting your headphones to your stereo.

Early on, the Apple Macintosh found a broad base of users in the desktop publishing and graphics art design market, where high-quality graphics and "What You See Is What You Get" (WYSIWYG) mattered. To date, Macintosh computers still have a stronghold on this segment of the industry. For example, Microsoft used Freehand on a Macintosh to create the Windows 95 logo, and Intel used Macintosh computers to create Intel Pentium ads; IBM-compatible manufacturers such as Gateway, and Dell use Macintosh computers to create print advertising; IBM and Microsoft also use Macintosh computers to create TV spots.

Apple gave away many of its computers to elementary schools, and targeted the higher education market hoping that students would eventually take the Macintosh into their homes and workplaces. Unfortunately, due to high up-front cost of purchasing an Apple Macintosh, it failed to compete with the ever-affordable IBM compatible. Ironically, the cost of maintaining an IBM-compatible computer is actually higher than an Apple Macintosh computer.

By December 1994, Apple decided that in order to keep up with market advances made by manufacturers of IBM-compatibles and Windows, it had better license its ROM and operating system to other manufacturers. This allowed companies such as Radius (later sold to Power Computing), Motorola, and Umax, to build and sell Macintosh compatibles, with the hope that market competition would drive prices down.

This experiment yielded spectacular results, in that non-Apple Macintosh computers were actually out-performing Apple Macintosh computers; Power Computing (the biggest Macintosh clone manufacturer) took away many loyal Apple customers by offering cheaper and faster high-end Macintosh computers. Apple made most of its profits by selling high-end computers, and could not afford to lose this segment of the market. Power Computing with its 10% of the Macintosh clone market share, was bought out by Apple in September 1997. With this acquisition, Apple pretty much eliminated its competition and ROM licensing had in effect died; Umax and Motorola still hold licenses to manufacture Apple clones, but they each had only 5% of the Macintosh clone market share.

For those who write computer software (especially for small software development companies), it was easier to support their livelihoods by producing software for computer systems that sold well. Thus, more software developers produce software for IBM-compatible than Apple Macintosh computers. One can find a good number of programs produced for elementary schools (long-time Apple Macintosh strongholds), and desktop-publishing and graphic design (such as Photoshop, Illustrator, QuarkXPress). However, the availability of Macintosh software for other disciplines is dramatically fewer. As of this writing, there are about 25 million Apple Macintosh computers in the world, and market share has dropped to the 5% range.

Microsoft's recent releases of Windows (95/98) have given IBM-compatibles a much more Apple Macintosh feel to the operating system, at very inexpensive costs. The underlying structure is still an "improved version of the good old DOS", and its command-line interface underpinnings are easily visible whenever one creates shortcuts (these shortcuts are analogous to Macintosh Aliases), and saving files. Admittedly, many swear by the command-line interface, while novices tend to swear at its demand for hair-splittingly accurate commands.

The file structure in Windows is an improved version of the old DOS file structure. To implement Macintosh-like abilities to save files using long filenames (those that can contain more than 8 characters), Microsoft designers use directory extension tricks to save long filenames. The reason it has been difficult to create a completely different file structure for Windows, is because it has to support the large base of users who still use legacy DOS programs and files.

Windows' Plug-And-Play feature still has more catch up work to do with Apple Macintosh's Plug-And-Play. Almost every manufacturer of peripheral devices for IBM-compatible computers have a unique set of drivers to communicate with the computer's hardware; when computer devices (keyboard, mouse, printer, hard drive, scanner, etc.) wished to communicate with the computer, signals were sent through Interrupt Requests (IRQs) "lines". If a user installs a new modem or SCSI card using an IRQ number taken by another device, one or both of the devices would be disabled. Windows attempts to automatically manage IRQs to minimize conflicts and differences introduced by competing peripheral manufacturers.

Apple Macintosh's operating system is tightly integrated with the BIOS, and there has been a long standing effort to standardize software and peripheral device interfaces used for Macintosh computers. As a result, Macintosh computers use less software files and hard disk space to run programs, and its users enjoy true Plug-And-Play.

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Two nagging weaknesses on the current Macintosh operating system are its lack of Preemptive Multitasking, and Memory Protection. Preemptive Multitasking can improve response time for higher-priority tasks (for example, opening a file), by taking away CPU resources from a lower priority task (for example, formatting a disk). Memory Protection prevents a program from interfering with another program's memory space; this feature prevents a system failure when one program overwrites (by design or by mistake) another program's data.

IBM-compatibles use some version of the 8088 (XT) or 80x86 (AT) CPU, manufactured by Intel, AMD, or Cyrix. The Apple Macintosh use some version of the 680x0 (68K) or 60x (PowerPC) CPU, manufactured by Motorola and Apple's one time rival: IBM. Space does not allow me to give a detailed comparison between these computer architectures.

However, the CPU used in early IBM-compatibles (XTs) and early Macintosh computers (68K) used Complex Instruction Set Computing (CISC) firmware. The Macintosh PowerPC CPU uses Reduced Instruction Set Computing (RISC) firmware. The CPU used in recent IBM-compatibles (ATs) such as the 486, and Pentium contain a mixture of CISC and RISC firmware. Again, the need to maintain backward compatibility with many older programs, has CPU manufacturers preserving older CISC instructions in the firmware of modern IBM-compatibles. Jeff Prosise has a good article describing differences between RISC and CISC at

CPU clock speed has seen a remarkable increase, and much of it is not really important to business applications. What is fueling the CPU clock speed race is the gaming software industry; in other words, that 166Mhz computer will serve you as well as that 400Mhz computer, if you're just using the machine to run your word processor and spreadsheet. Contrary to popular belief, the clock speed (cycles per second) of the computer's CPU does NOT always tell the whole story about the computer's processing speed. Some CPUs can process more instructions per cycle than another similarly clocked device. Besides processor clock speed, the type and size of cache, the speed and amount of Random Access Memory (RAM) also affect overall processing speed.

Apple has made many claims in its advertising, that it is faster than IBM-compatible computers. There are many ways to measure the speed of a CPU, and one of the most popular ways is to measure how many million instructions a CPU can perform in one second (MIPS). The MIPS rating taken by itself can be deceptive, because the set of instructions used in the measurement may not be the same set of instructions used in real life. In order to fairly compare one CPU's speed with another, benchmarks containing similar sets of instructions are used to perform these measurements.

The difficulty in comparing the Apple Macintosh to the IBM-compatible is that these CPU's use different mixtures of instructions. In response, some propose to compare the speed with which both systems perform similar tasks. Several software packages written for the Apple Macintosh (such as Adobe Photoshop and Illustrator) have been optimized for the PowerPC to take full advantage of the CPUs reduced instruction set.

A non-optimized version of Adobe Photoshop running on a Pentium can be 4 times slower in performing a Gaussian blurr, than an optimized version of Adobe Photoshop running on a similarly equipped PowerPC computer. Many improvements made by the newer PowerPC processor were not immediately evident, because important I/O portions of the Macintosh Operating System (before version 8.0) were not optimized. This resulted in parts of the Finder running in emulation mode, which translated to longer times to print documents, open files and programs. While optimization is a worthwhile technological development, it is not fair to use the measurements of an optimized system, to claim that the CPU itself is faster than another system running software that has not been optimized.

The availability of optimized software for the Apple Macintosh makes owning a PowerPC computer more desirable, but this choice would have been made on the grounds of "optimized software", and hardware capable of supporting said optimization. Intel's MMX-enabled CPUs are capable of executing instructions that handle audio, video, and graphics data more efficiently than non-MMX CPUs.

The difference between MMX optimized code and PowerPC (native) code is that the 57 new instructions in an MMX-enabled CPU only affect multimedia data. PowerPC native code has been written into hundreds of desktop-publishing and graphic design applications, and scientific applications that use the new PowerPC floating point processor. More importantly, the Macintosh Operating System 8.0 and above, has been completely optimized for the PowerPC. A test using the older OS 7.6 and optimized versions of Photoshop for IBM-compatibles and Apple Macintosh computers was published by MacUser, and you can read about it in

So what computer should you buy? You should start by identifying what needs you have. What do you need the computer for? Do you need a simple interface? How reliable do you need your computer system to be? In my opinion, if you use the computer for desktop-publishing, graphic art design, fractal simulations, and interface simplicity and low maintenance cost is high on your priority list, I would recommend an Apple Macintosh computer. If you don't mind the command-line interface (and actually like to type in commands), you wish to use the computer to write programming assignments, and you don't mind taking apart computers, I would recommend an IBM-compatible computer.

Next, you should consider what computers others in your field of expertise use, and the availability of software. Do you need to share files with others? Are there software packages available for the computer of your choice, which you will use in your field of expertise?

If you are in a desktop-publishing, graphic art design, or advertising field, chances are your colleagues --and colleagues to be-- already use an Apple Macintosh. While you can find programs that allow you to share files with others who might be using a different computer than yours (for example, the built-in PC Exchange on Macintosh computers, and shareware called TransMac for IBM-compatibles), it is always preferable to stick with a system that your colleagues already use. Most importantly, you need to make sure that the software you are going to use will continue to be available and supported. If you are involved in a field where most people in your discipline use IBM-compatibles, and you can easily find software you need for the IBM-compatible in your favorite software store (Best Buy, Office Depot, Staples, etc.), I would recommend an IBM-compatible computer.

How much are you willing to pay for the "computer system of your dreams"? An IBM-compatible typically costs 60% of a comparable Macintosh computer system. Warning: the cost of ownership is often more important than the cost of purchasing computer hardware.

In October 1995, Gartner Consulting Group reported that the Macintosh is 25% less expensive to support than an IBM-compatible computer. According to an estimate by Todd Windemuth, Director of Computer Information Services at La Sierra University, the cost of maintaining Apple Macintosh computers on campus has been about 65% of the cost of maintaining IBM-compatible computers. The mixture of Macintosh and IBM-compatible computers has dropped from 35/65, to 20/80. Much of the cost of maintaining IBM-compatible computers are incurred by repairing network printing problems, and substandard parts used in cheaper IBM-compatible computers.

Because Apple has owned its operating system and hardware, there have been fewer software problems to speak of. As software support provider at La Sierra University, of all the phone calls I receive for software support, less than a fifth of these calls come from Macintosh users. Historically, Macintosh users have had fewer problems with their computer systems than fellow IBM-compatible users.

There are several promising developments in the Apple camp. Increasing G3 and iMac sales are catching the attention of several important software developers. The upcoming Rhapsody (also known as Mac OS X) will be an all-around highly modular and object-oriented Macintosh operating system, that will even run on an IBM-compatible computer. The most important features about MacOS X will be preemptive multitasking, memory protection, and a better virtual memory manager.

In my opinion, the Windows 95 and 98 project is in a technological mess, because it has had to maintain backward compatibility with legacy DOS programs. To the extent that Microsoft is able to steer its current Windows customers to Windows 2000 without alienating legacy DOS users, Windows 2000 (based on the Windows NT project) would be a realistic threat to Apple's operating system.

In summary, I believe that the Macintosh computer has and will probably continue to offer a technologically superior personal computing product, even if it has failed to compete in an environment where marketing and affordability matters more than technological sophistication. Your purchasing decisions should however be based on what you need your computer to do for you. The lack of software for the Macintosh has steered many towards IBM-compatible computers, and the choice between the two depends largely on what your discipline is. You probably don't need the fastest CPU; instead, go for the largest cache and memory you can find and afford. Finally, after all is said and done, you get what you paid for.

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