Model 5150 | 1981 ~ 1987
Model 5150
The IBM Personal Computer (model 5150, commonly known as the IBM PC) was the first microcomputer released in the IBM PC model line and laid the foundation for the IBM PC-compatible standard. It was released on August 12, 1981, and was developed by a team of engineers and designers led by William C. Lowe and Philip Don Estridge at IBM's Boca Raton, Florida, location.
The computer was powered by the Intel 8088 processor based on the x86 architecture and adopted an open architecture and third-party peripherals. Over time, the expansion cards and software technologies increased to support it. The IBM PC had a significant impact on the personal computer market, and its specifications became one of the most popular computer design standards in the world. Throughout the 1980s, the primary competitors to the IBM PC were Apple’s Macintosh product line and consumer platforms created by companies like Commodore and Atari. Today, most personal computers share common architectural features with the original IBM PC, including Intel-based Apple Macs manufactured between 2006 and 2022.
In the early 1980s, IBM was primarily known as a business computer systems provider. As the microcomputer market was seeing impressive profits, IBM’s market share in the minicomputer sector was falling behind. At the time, the personal computer market was dominated by machines selling for only a few hundred dollars, created by companies like Tandy, Commodore, and Apple. By 1979, the microcomputer market size had reached $15 billion, with annual growth rates exceeding 40% expected in the early 1980s. This growth attracted other major tech companies, including Hewlett-Packard, Texas Instruments, and Data General. Some of IBM's larger clients were already purchasing Apple products.
In the early 1980s, rumors began circulating that IBM was developing a personal computer. Given that IBM traditionally focused on large, complex business systems, many were skeptical about the possibility of an IBM personal computer. IBM typically took 4-5 years to develop new products, and industry analysts even remarked that "teaching a rhinoceros to tap dance would be easier than IBM launching a personal computer."
Although IBM had previously produced microcomputers like the IBM 5100 in 1975, these were business products. The $20,000 5100 was sold primarily for business use. IBM's entry into the consumer computer market needed to be competitively priced.
In 1980, IBM President John Opel decided that it was crucial to enter this growing market and assigned William C. Lowe and Philip Don Estridge to lead the development of a new "entry-level system" division, based in Boca Raton, Florida. Market research revealed that computer dealers wanted IBM to use standard parts rather than components designed by IBM, so that stores could service the products themselves. Another reason for this decision was the time constraints, as using third-party parts would speed up development.
In 1980, Atari proposed that IBM manufacture its microcomputers as an OEM product, which would have addressed IBM's inability to respond quickly to the fast-moving market. However, IBM rejected the offer. Instead, Lowe formed an independent internal team and proposed that by abandoning IBM’s traditional development methods, they could complete the design within a year and build a prototype in just 30 days. While the prototype didn't work properly, the business plan was comprehensive and predicted that the new computer would use an open architecture with non-proprietary parts and software, which could lead to higher sales than initially expected.
IBM’s executive committee approved the proposal, transitioning the group into a business unit called "Project Chess" and provided them with the necessary funding and authority. By the end of 1980, the team grew to 150 members, and over 500 IBM employees expressed interest in joining the project.
The design process was kept secret, with other IBM departments unaware of the project. Several types of CPUs were considered, including the Texas Instruments TMS9900, Motorola 68000, and Intel 8088. While the 68000 was seen as the best choice, it wasn’t ready for production, so the Intel 8088 was selected due to its better price and greater availability.
The 8088 motherboard was designed in 40 days, and within 4 months, a working prototype was created. The design was completed in April 1981 and handed over to the manufacturing team. The computer was assembled at IBM's Boca Raton facility in Florida, with components sourced from both IBM and third-party factories. The monitor design was taken from IBM Japan, and the printers were made by Epson. Because IBM did not design the functional components of the PC, it obtained several patents related to the PC but did not enforce them.
Many of the designers were personal computer enthusiasts who owned their own computers, with many being owners of the Apple II. These individuals influenced the design decisions to adopt an open architecture and make technical information available so that others could create compatible software and expansion peripherals. During the design process, IBM aimed to avoid vertical integration as much as possible. For example, instead of using IBM's proprietary BASIC for mainframes, IBM licensed Microsoft's BASIC for the PC.
The IBM PC was launched on August 12, 1981, after 12 months of development. The base price started at $1,565 for a configuration with 16 KB RAM, a color graphics adapter, and a keyboard without a disk drive. This price was designed to compete with similar machines in the market. To put it in context, IBM's cheapest computer, the Datamaster, had a price of $10,000 just two weeks after its release.
IBM's marketing campaign used Charlie Chaplin's character "The Little Tramp" in a series of ads, with Billy Scudder playing the role. IBM also decided to sell the computers through retail channels, rather than directly to customers. IBM, lacking experience in retail, collaborated with ComputerLand and Sears to gain insight into the market. ComputerLand already had over 190 stores, and Sears was in the process of setting up computer centers.
The reaction after the release was very positive. Analysts predicted billions of dollars in sales within a few years. IBM's PC quickly became a major talking point in the computer industry. Dealers were overwhelmed with orders, and some customers even paid deposits for machines that had no delivery guarantee. As the machines began shipping, the term "PC" had already become widely used in households.
Sales exceeded IBM's expectations by more than 800%, and at one point, IBM was shipping up to 40,000 PCs a month. IBM estimated that 50–70% of the PCs sold in retail were bought by home users. By 1983, IBM had sold over 750,000 PCs, while Digital Equipment Corporation had sold only 69,000 units.
Software support grew rapidly, and IBM quickly became the primary target for most microcomputer software developers. One publisher reported that a year after the PC launch, 753 software packages were available, four times as many as for the Macintosh, which launched a year later. Hardware support also grew quickly, with 30-40 companies competing to sell memory expansion cards within a year.
By 1984, IBM's PC revenue reached $4 billion, double that of Apple. A 1983 survey of corporate customers found that two-thirds of large companies had standardized on the PC, compared to only 9% for Apple. A 1985 Fortune survey reported that 56% of U.S. companies using personal computers were using PCs, while only 16% were using Apple machines.
Soon after the release of the IBM PC, rumors of clones began circulating, and the first legal PC-compatible clone, the MPC 1600, appeared in June 1982, less than a year after the PC’s release. Eventually, in 2004, IBM sold its PC business to Lenovo.
The hardware design of the IBM PC was built using off-the-shelf components from third-party manufacturers to enable fast design cycles and low costs. The PC's case was designed with a wide, short steel chassis to support the weight of the CRT monitor. The front panel was made of plastic, and it featured slots for one or two disk drives. The rear panel included power inlets, switches, keyboard connection ports, cassette ports, and vertical expansion slots for additional cards.
Internally, the PC was built around a motherboard that housed the CPU, built-in RAM, expansion RAM sockets, and expansion card slots. The IBM PC was designed for expandability and upgradeability, with a base configuration including the following specifications:
- CPU: Intel 8088 @ 4.77 MHz
- RAM: 16 KB or 64 KB (expandable up to 640 KB)
- Video: IBM Monochrome Display Adapter or IBM Color Graphics Adapter
- Display: IBM 5151 Monochrome Display or IBM 5153 Color Display
- Input: IBM Model F 83-key keyboard
- Storage: Up to two internal 5.25-inch floppy disk drives
- Expansion: 5 62-pin expansion slots, IBM 5161 expansion chassis (7 slots available)
- Communication: Optional serial and parallel ports
The IBM PC was composed of a motherboard, which was a single large circuit board containing the CPU, built-in RAM, expansion slots, keyboard and cassette ports, and various integrated circuits that controlled peripheral devices. The CPU was the Intel 8088, which was a cost-reduced version of the 8086, retaining most of the internal 16-bit logic while using an 8-bit bus. The CPU operated at 4.77 MHz, which later caused compatibility issues as clones and subsequent PC models offered faster CPUs.
IBM added a math coprocessor socket to the PC, allowing users to add the Intel 8087 math coprocessor to enhance floating-point performance. The PC's mainboard had 16 KB or 64 KB of RAM soldered in, and it could be expanded using three additional RAM banks and ISA expansion cards.
Unlike most home computers of the time, the IBM PC offered two unique graphics options. One was the MDA card, which provided high-resolution black-and-white text, and the other was the CGA card, which allowed for color graphics with a maximum of 320×200 resolution. Later on, other graphics cards like the EGA and VGA were introduced to improve display capabilities further.
The IBM PC’s software platform was initially limited, with many third-party software applications appearing for the platform, and some programs designed for specific business applications like accounting, word processing, and spreadsheets. Early software came from IBM itself (e.g., PC-DOS) and Microsoft (e.g., MS-DOS).
The IBM PC's open architecture and compatibility helped it become an instant success, and the clone market quickly blossomed. In just a few years, the IBM PC-compatible market became a dominant force, leading to the "IBM PC compatible" label becoming synonymous with personal computers for many years.
