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The MS-DOS Encyclopedia


Microsoft's MS-DOS is the most popular piece of software in the world.
It runs on more than 10 million personal computers worldwide and is
the foundation for at least 20,000 applications--the largest set of
applications in any computer environment. As an industry standard for
the family of 8086-based microcomputers, MS-DOS has had a central role
in the personal computer revolution and is the most significant and
enduring factor in furthering Microsoft's original vision--a computer
for every desktop and in every home. The challenge of maintaining a
single operating system over the entire range of 8086-based
microcomputers and applications is incredible, but Microsoft has been
committed to meeting this challenge since the release of MS-DOS in
1981. The true measure of our success in this effort is MS-DOS's
continued prominence in the microcomputer industry.

Since MS-DOS's creation, more powerful and much-improved computers
have entered the marketplace, yet each new version of MS-DOS
reestablishes its position as the foundation for new applications as
well as for old. To explain this extraordinary prominence, we must
look to the origins of the personal computer industry. The three most
significant factors in the creation of MS-DOS were the compatibility
revolution, the development of Microsoft BASIC and its widespread
acceptance by the personal computer industry, and IBM's decision to
build a computer that incorporated 16-bit technology.

The compatibility revolution began with the Intel 8080 microprocessor.
This technological breakthrough brought unprecedented opportunities in
the emerging microcomputer industry, promising continued improvements
in power, speed, and cost of desktop computing. In the minicomputer
market, every hardware manufacturer had its own special instruction
set and operating system, so software developed for a specific machine
was incompatible with the machines of other hardware vendors. This
specialization also meant tremendous duplication of effort--each
hardware vendor had to write language compilers, databases, and other
development tools to fit its particular machine. Microcomputers based
on the 8080 microprocessor promised to change all this because
different manufacturers would buy the same chip with the same
instruction set.

From 1975 to 1981 (the 8-bit era of microcomputing), Microsoft
convinced virtually every personal computer manufacturer--Radio Shack,
Commodore, Apple, and dozens of others--to build Microsoft BASIC into
its machines. For the first time, one common language cut across all
hardware vendor lines. The success of our BASIC demonstrated the
advantages of compatibility: To their great benefit, users were
finally able to move applications from one vendor's machine to

Most machines produced during this early period did not have a built-
in disk drive. Gradually, however, floppy disks, and later fixed
disks, became less expensive and more common, and a number of disk-
based programs, including WordStar and dBASE, entered the market. A
standard disk operating system that could accommodate these
developments became extremely important, leading Lifeboat, Microsoft,
and Digital Research all to support CP/M-80, Digital Research's 8080

The 8-bit era proved the importance of having a multiple-manufacturer
standard that permitted the free interchange of programs. It was
important that software designed for the new 16-bit machines have this
same advantage. No personal computer manufacturer in 1980 could have
predicted with any accuracy how quickly a third-party software
industry would grow and get behind a strong standard--a standard that
would be the software industry's lifeblood. The intricacies of how
MS-DOS became the most common 16-bit operating system, in part through
the work we did for IBM, is not the key point here. The key point is
that it was inevitable for a popular operating system to emerge for
the 16-bit machine, just as Microsoft's BASIC had prevailed on the 8-
bit systems.

It was overwhelmingly evident that the personal computer had reached
broad acceptance in the market when Time in 1982 named the personal
computer "Man of the Year." MS-DOS was integral to this acceptance and
popularity, and we have continued to adapt MS-DOS to support more
powerful computers without sacrificing the compatibility that is
essential to keeping it an industry standard. The presence of the
80386 microprocessor guarantees that continued investments in Intel-
architecture software will be worthwhile.

Our goal with The MS-DOS Encyclopedia is to provide the most thorough
and accessible resource available anywhere for MS-DOS programmers. The
length of this book is many times greater than the source listing of
the first version of MS-DOS--evidence of the growing complexity and
sophistication of the operating system. The encyclopedia will be
especially useful to software developers faced with preserving
continuity yet enhancing the portability of their applications.

Our thriving industry is committed to exploiting the advantages
offered by the protected mode introduced with the 80286 microprocessor
and the virtual mode introduced with the 80386 microprocessor. MS-DOS
will continue to play an integral part in this effort. Faster and more
powerful machines running Microsoft OS/2 mean an exciting future of
multitasking systems, networking, improved levels of data protection,
better hardware memory management for multiple applications, stunning
graphics systems that can display an innovative graphical user
interface, and communication subsystems. MS-DOS version 3, which runs
in real mode on 80286-based and 80386-based machines, is a vital link
in the Family API of OS/2. Users will continue to benefit from our
commitment to improved operating-system performance and usability as
the future unfolds.

                                            Bill Gates

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