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The IBM Personal Computer

At the end of 1980, IBM decided to truly compete in the rapidly growing low-cost personal computer market. The company established what then was called the Entry Systems Division, located in Boca Raton, Florida, to develop the new system. This small group consisted of 12 engineers and designers under the direction of Don Estridge; the team's chief designer was Lewis Eggebrecht. The division developed IBM's first real PC. (IBM considered the 5100 system, developed in 1975, to be an intelligent programmable terminal rather than a genuine computer, even though it truly was a computer.) Nearly all these engineers had been moved to the new division from the System/23 DataMaster project, which in 1980 introduced a small office computer system that was the closest predecessor to the IBM PC.

Much of the PC's design was influenced by the DataMaster's design. In the DataMaster's single-piece design, the display and keyboard were integrated into the unit. Because these features were limiting, they became external units on the PC, although the PC keyboard layout and electrical designs were copied from the DataMaster.

Several other parts of the IBM PC system also were copied from the DataMaster, including the expansion bus (or input/output slots), which included not only the same physical 62-pin connector but also almost identical pin specifications. This copying was possible because the PC used the same interrupt controller as the DataMaster and a similar direct memory access (DMA) controller. Expansion cards already designed for the DataMaster could then be easily re-designed to function in the PC.

The DataMaster used an Intel 8085 CPU, which had a 64K address limit, as well as an 8-bit internal and external data bus. This arrangement prompted the PC design team to use the Intel 8088 CPU, which offered a much larger (1M) memory address limit, and an internal 16-bit data bus, but only an 8-bit external data bus. The 8-bit external data bus and similar instruction set allowed the 8088 to be easily interfaced into the earlier DataMaster designs.

Estridge and the design team rapidly developed the design and specifications for the new system. In addition to borrowing from the System/23 DataMaster, the team studied the marketplace, which also had enormous influence on the IBM PC's design. The designers looked at the prevailing standards, learned from the success of those systems, and incorporated into the new PC all the features of the popular systems--and more. With the parameters for design made obvious by the market, IBM produced a system that filled its niche in the market perfectly.

IBM brought its system from idea to delivery in one year by using existing designs and purchasing as many components as possible from outside vendors. The Entry Systems Division was granted autonomy from IBM's other divisions and could tap resources outside the company, rather than go through the bureaucratic procedures that required exclusive use of IBM resources. IBM contracted out the PC's languages and operating system to a small company named Microsoft. That decision would be the major factor in establishing Microsoft as the dominant force in PC software today.

NOTE:It is interesting to note that IBM had originally contacted Digital Research (the company that created CP/M, then the most popular Personal Computer operating system) to have them develop an operating system for the new IBM PC, but they were leery of working with IBM, and especially balked at the non-disclosure agreement IBM wanted them to sign. Microsoft jumped on the opportunity left open by Digital Research, and as a result has become one of the largest software companies in the world. IBM's use of outside vendors in developing the PC was an open invitation for the aftermarket to jump in and support the system--and it did.

On Wednesday, August 12, 1981, a new standard was established in the micro- computer industry with the debut of the IBM PC. Since then, hundreds of millions of PC-compatible systems have been sold as the original PC has grown into an enormous family of computers and peripherals. More software has been written for this computer family than for any other system on the market.

The IBM-Compatible Marketplace 16 Years Later

In the more than 16 years since the original IBM PC was introduced, many changes have occurred. The IBM-compatible computer, for example, advanced from a 4.77MHz 8088-based system to 300MHz or faster Pentium II-based systems--nearly 2,000 times faster than the original IBM PC (in actual processing speed, not just clock speed). The original PC had only one or two single-sided floppy drives that stored 160K each using DOS 1.0, whereas modern systems easily can have 10G (10 billion bytes) or more of hard disk storage. A rule of thumb in the computer industry is that available processor performance and disk-storage capacity at least double every two to three years. Since the beginning of the PC industry, this pattern has shown no sign of changing.

In addition to performance and storage capacity, another major change since the original IBM PC was introduced is that IBM is not the only manufacturer of "PC-compatible" systems. IBM originated the PC-compatible standard, of course, and it continues to set standards that compatible systems follow, but the company does not dominate the PC market as it did originally. More often than not, new standards in the PC industry are developed by companies and organizations other than IBM. Today it is Intel and Microsoft who are primarily responsible for developing and extending the PC hardware and software standards, respectively. Some have even taken to calling PCs "Wintel" systems, owing to the dominance of those two companies.

Even so, there are literally hundreds of system manufacturers producing computers that are fully PC compatible, not to mention the thousands of peripheral manufacturers whose components expand and enhance PC-compatible systems.

PC-compatible systems have thrived, not only because compatible hardware can be assembled easily, but also because the primary operating system was available not from IBM but from a third party (Microsoft). The core of the system software is the BIOS (Basic Input Output System), and this was also available from third-party companies like AMI, Award, Phoenix, and others. This situation allowed other manufacturers to license the operating system and BIOS software and to sell their own compatible systems. The fact that DOS borrowed the functionality and user interface from both CP/M and UNIX probably had a lot to do with the amount of software that became available. Later, with the success of Windows, there would be even more reasons for software developers to write programs for PC-compatible systems.

One of the reasons why Apple Macintosh systems will likely never enjoy the success of PC-compatibles is that Apple controls all the software (BIOS and OS), and until recently had not licensed any of it to other companies for use in compatible systems. Apple now seems to recognize this flawed stance because they have begun to license this software; however, it seems too late for them to effectively compete with the PC-compatible juggernaut. It is fortunate for the computing public as a whole that IBM created a more open and extendible standard. The competition among manufacturers and vendors of PC-compatible systems is the reason why such systems offer so much performance and so many capabilities for the money.

The IBM-compatible market continues to thrive and prosper. New technology continues to be integrated into these systems, enabling them to grow with the times. Because of the high value that these types of systems can offer for the money and the large amount of software that is available to run on them, PC-compatible systems likely will dominate the personal computer marketplace for perhaps the next 15 to 20 years as well

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