Twenty-five years ago, IBM changed the world. It wasn't intentional. When Big Blue announced a microcomputer called the IBM Personal Computer on August 12, 1981, it hoped only to make a nice profit.

The company did make money--but more important, the IBM PC, also known as the Model 5150, made a significant impact on the culture. Today, for instance, we call our desktops and laptops PCs, not microcomputers. The vast majority of the ubiquitous machines scattered around our offices and homes are direct descendents of IBM's 25-year-old box.

Former IBM engineer David J. Bradley joined the microcomputer project in September 1980. It was "one of those things that engineers dream about...a brand new thing; a blank piece of paper."

Before the IBM PC, business computers were mainframes or minis, large and expensive investments that weren't intended for a single person's use. Since the resources were shared, computing jobs ran slowly during business hours when everyone was at work. Dedicated, technology-savvy employees would often work through the night.

Personal computers existed prior to the IBM PC--the Apple II came out in 1977, and the Atari 800 came out in 1979, for example. However, these systems used proprietary components and designs.

IBM was in a hurry, so Bradley and his coworkers had to break company policy and use other people's technology, including a processor from Intel and an operating system from Microsoft. The PC's lack of IBM-owned technology made cloning possible, and cloning--Columbia Data Products' MPC 1600-1 in 1982 was the first clone--made the PC a standard. "If we'd [built the PC] from the ground up," Bradley told me, "we wouldn't be having this conversation right now."

Although extremely significant, the original IBM PC ranks only sixth in PC World's list of The 25 Greatest PCs of All Time.
Something Special

The final result of the IBM team's work was a cool, grey, horizontal box. The keyboard and monitor were not built in, but attached with cables--common today but somewhat unusual then. If you didn't want to load programs and save files on a cassette tape, a floppy drive cost extra, as did a printer.

But the PC wasn't only well made, it was well documented, which contributed to successful cloning. Dan Bricklin, cocreator of VisiCalc, the first spreadsheet program, recalls that IBM "provided wiring diagrams and BIOS listings with comments that made it easy for programmers to write for this thing."

It wasn't your only PC choice in the early 1980s. Many popular microcomputers of the day ran an operating system from Digital Research called CP/M. Commodore's PET 2001 and Tandy's TRS-80 Model I were also established players. And two guys named Steve had a big business going with the Apple II.

But this computer had the IBM imprimatur. In 1981, if you told your employer that you wanted an Apple or an Atari, well, bosses in that era tended to think of those machines as toys. The name IBM probably did more for the PC's initial success than any other factor. Big Blue had a serious image that contrasted with the hobbyist nature of previous microcomputers.

Bradley says the question of the day was: "Do you want to buy a computer from International Business Machines or from a company named after a fruit?"
Software Contributors

Members of the IBM team weren't the only ones involved in getting the IBM PC out the door. Bricklin remembers receiving a prototype of the IBM PC, "a piece of plywood with a motherboard," well before that August date.

Dan BricklinIBM wanted him to port VisiCalc to the new platform, as it was one of the few business-oriented programs then available for microcomputers. Bricklin remembers the first IBM PC as "a really well-done machine," expandable, with a "very readable [monochrome] screen" and "a great keyboard." Two decades later, he collected his memories about the project in an essay titled "Thoughts on the 20th Anniversary of the IBM PC."

Mitch KaporMitch Kapor, whose Lotus 1-2-3 would soon supplant VisiCalc as the leading PC spreadsheet, got no early preview. But he was impressed by IBM's use of the 16-bit Intel 8088 processor. "I thought to myself, 'there's somebody very smart inside IBM,'" he says.

The 8088 had an additional advantage over its stablemate, the 16-bit 8086: It used an 8-bit data bus. So, although it could run 16-bit applications and address a full megabyte of memory, it was paired with existing 8-bit components, which kept its cost comparable to its 8-bit competition and ensured its success.

Of course, what impressed people in 1981 can seem laughable today. When Phil Lemmons, later a PC World editor in chief, reviewed the IBM PC in the October 1981 issue of Byte magazine, he was careful to note: "The system supports both uppercase and lowercase characters." (The original Apple II supported only uppercase characters.)

Others weren't that overwhelmed. Frank Wylie, now a lab supervisor for the
Library of Congress Motion Picture Division, was then a computer-savvy adolescent who owned an Atari. "From the standpoint of a 13-year-old, [the IBM machine] didn't have any of the fancy graphics," Wylie remembers. In comparison, the Apple II and the Atari 800 both offered color graphics by that time.

Nobody was really prepared for the IBM PC's instant, explosive success, especially for a machine whose $1265 base model didn't include a monitor, video card, parallel or serial port, operating system, or floppy drive. In 2001, Bradley told PC World that IBM hoped to sell 241,683 PCs over five years. Before those five years were up, the company was selling nearly that many units a month.
The Ghost in the Machine

Of course, IBM no longer makes PCs. In the mid-1980s the company attempted to take back control of the standard with a significant upgrade--the Micro Channel Architecture PS/2, which was software-compatible, but not hardware-compatible, with the PC. However, it was Compaq, the first and largest of the clone manufacturers, that offered the upgrade everyone really wanted: a PC based on Intel's 32-bit 80386 processor.

Big Blue remained a major player in the PC market throughout the 1990s, but it was no longer the biggest player. During that time it concentrated on its ThinkPad notebooks rather than desktop PCs. In 2005 IBM sold its PC division, including the ThinkPad, to the Lenovo Group.

The IBM PC is, according to Kapor, "clearly the lineal ancestor. Ninety-eight percent of the genes in its DNA are the same, but functionally today's PCs are different."

Today's computers are especially changed in how data moves in and out of them. Early PCs had no optical drives or hard drives; initially, having even a floppy drive was a nice upgrade over tape storage. Other advances we take for granted, such as PCI slots and USB ports, were still many years in the future. Modern PCs lack 5.25-inch floppy drives (if they have a floppy drive at all), parallel and serial ports, and ISA slots. "The only thing that is really the same between the original and today's [PC hardware]," says Bricklin, "is the power connector."

But today's PC can still run a great deal of early DOS software, including Bricklin's 1981 version of VisiCalc, now available for free from his Web site.There's no question about it: Bradley and his long-ago collaborators created something that lasted long beyond their hopes and expectations. Had he known, would Bradley have done anything differently? Yes, indeed. "I would have bought shares of Microsoft and Intel," he says.