the best features of the I486 and I860, introducing
the Pentium 1, which contained 3.1 million transis-
tors and was a major technical and commercial suc-
cess. The Pentium II, released in 1997, had 7.5 mil-
lion transistors; the Pentium III, released in 1999,
had 20 million transistors; and the Pentium IV, re-
leased in 2000, had 42 million transistors. Even al-
lowing for differences in the transistor count cre-
ated by Intel’s move from single chips to slot-based
CPUs, the improvements in Intel CPUs over the
1990’s were phenomenal.
In addition to CPU improvement in the 1990’s,
there were many improvements in peripheral de-
vices. Of the numerous products introduced or im-
proved, some of the most important were the
Microsoft IntelliMouse (1996), the Iomega Zip drive
(1999), and numerous improvements in hard drives
(1990-2000) and DVD storage (1997). Several new
standards were released in the 1990’s, including the
plug and play (1993), which made it much easier to
add software drives to an operating system, and the
USB standard (1995), which allowed many new de-
vices to be attached to a microcomputer.
Operating Systems While there were many ad-
vances in software in the 1990’s, no type of software
developed faster than operating systems. The UNIX
operating system was introduced in 1969, adapted to
microcomputers as XENIX in 1970, and experi-
enced steady growth during the 1980’s. By 1991, a
number of companies had robust versions of UNIX
running on their computers, including IBM’s AIX,
Sun Microsystems’ SunOS, and DEC’s OpenVMS. In
1994, Linus Torvalds introduced a free version of
UNIX called Linux, which runs on both microcom-
puters and large servers. After its introduction,
Linux experienced very rapid adoption, and by 2000
it was not only being distributed as freeware but also
sold by many computer companies. About 1992, Sun
released Solaris as its latest version of UNIX and has
used Solaris since then. Many other companies de-
veloped their own flavor of UNIX during the 1990’s,
including HP, Silicon Graphics (Cray), Apple Com-
puter, and Santa Cruz Operations (SCO). All ver-
sions of UNIX, as well as Windows NT, used a num-
ber of concepts of the Mach kernel UNIX project at
Carnegie Mellon.
In 1990, Microsoft and IBM stopped collaborat-
ing on the OS/2 operating system. IBM continued
to market OS/2 and had some success with its OS/2
Wrap, released in 1994. However, the failure of the
PS/2 led to the demise of OS/2. IBM developed sev-
eral versions of UNIX over the 1990’s, which were
fairly successful. The major operating systems story
at IBM during the 1990’s was the transition of its
mainframe MVS operating system to its VM line of
super-server operating systems. The VM server oper-
ating system is the largest single-server operating sys-
tem today.
The advances in operating systems made at
Microsoft during the 1990’s are unsurpassed by any
other company. In 1992, Microsoft released Win-
dows 3.1, and while this operating system had techni-
cal limitations, its reception by businesses and home
users made it the most commercially successful op-
erating system in history. The ease of adding applica-
tions to Windows 3.1 and the relatively user-friendly
interface made it an immediate success. Windows
NT was released by Microsoft in 1993. It embodied
the best features of the Mach kernel UNIX,
OpenVMS, and the Motif graphical user interface
(GUI). Windows NT was both a technical and com-
mercial success. With Windows 95, Microsoft finally
got a solid technical foundation to support its out-
standing GUI and application extensibility. Win-
dows 95 was almost as big a success story as Windows
3.1. Windows 98 and Windows Millennium Edition
(2000) were also technical and commercial suc-
cesses, but Microsoft brought this line of operating
systems to a halt in 2001 with its introduction of Win-
dows XP.
Not all of Microsoft’s operating systems efforts in
the 1990’s were successful. The most notable exam-
ples of Microsoft failures were Bob (1995), with its
gamelike interface, and Windows CE (1996), de-
signed to support small computers. Bob failed to
gain any acceptance from nontechnical users, and
Windows CE was not as well received as the
Palm OS.Net-Centric Computing in a Connected World A
number of handheld devices, like the U.S. Robotics
Palm Pilot (1996) and the BlackBerry (1999), com-
bined aspects of communications, entertainment,
and information. This, combined with the matura-
tion of the Internet as a communications network,
enabled many people to actively use their handheld
devices to communicate, listen to music, or browse
the World Wide Web. In the 1990’s, many businesses
realized that telecommuting and communicatingThe Nineties in America Computers 217