IBM PC-5150
When IBM announced its Personal Computer 5150 in August 1981, the company entered a market six years behind Apple, Atari, Commodore, and Radio Shack. This late arrival forced Big Blue to break with tradition: internal development gave way to external partnerships. A team of just twelve people would design this machine in one year, a record for IBM.
The approach was surprising. Intel supplied the processor, Microsoft delivered PC-DOS and BASIC. Distribution also broke with tradition: instead of its own channels, IBM chose Computerland and Sears. For advertising, the company abandoned its austere image and featured Charlie Chaplin's Tramp character in a series of offbeat television spots.
At $1,565 for the base model, without floppy drive or screen, the PC 5150 initially targeted individuals. They could connect their television as a monitor and use a tape recorder to save their data. Business users, however, paid $4,500 for a complete configuration with 64 KB of memory, two floppy drives, color display, and dot matrix printer. Adjusted for inflation and converted to current Swiss francs, these amounts would reach 6,000 and 14,000 CHF.
Technically, nothing spectacular. The Intel 8088 processor ran at 4.77 MHz, a thousand times less than our current chips. This economical derivative of the 8086 made do with an 8-bit data bus while addressing up to 1 MB of memory. The motherboard accommodated between 16 and 64 KB of RAM, two 5.25-inch drives of 160 KB each.
A few details nevertheless marked a break. The detached keyboard was exceptional at a time when most computers integrated it into the main unit. Its 83 keys weighed 2.7 kg and produced that characteristic click that would delight nostalgic users. The system unit with its drives weighed 12.7 kg, the monitor 7.7 kg. Total: 23 kg of home computing.
No standard hard drive, that would require the 5161 expansion. No mouse either, it wouldn't become widespread until later. Storage used audio cassettes via a specialized connector or floppy disks. Early versions used single-sided 160 KB media, then double-sided 360 KB for the Model B marketed as early as 1983.
IBM surprised with its technical transparency. The documentation provided with the PC 5150 revealed everything: electronic schematics, architecture diagrams, interface specifications, BIOS source code. This unusual openness boosted the creation of expansion cards and compatible software. But it also opened the door to cheaper clones that would proliferate.
Five internal slots accepted expansions via what IBM called the "I/O Channel", predecessor of the ISA standard. These 62-pin connectors accommodated floppy controllers, graphics adapters, parallel interfaces for printers, or RS-232 serial ports for modems. Contemporary PCs have abandoned these parallel buses for faster serial connections like PCI Express or USB.
PC-DOS managed files with the FAT system, without subdirectories in its first iteration. All files spread out in a flat structure: 64 maximum on single-sided floppy, 112 on double-sided. Computer viruses and piracy, though they existed, had not yet infected the planet. The manual addressed only physical security: storing diskettes safely, backing up regularly, controlling machine access. The first virus for IBM-compatible PCs, Brain, wouldn't appear until 1986.
Production of the 5150 stopped in 1987, replaced by the 5160 model. Internationalization began in 1983. Its architecture still influences our current machines, from connected objects to enterprise cloud servers. IBM's choices—standardized components, comprehensive documentation—created an open ecosystem that would dominate the market.