Acorn

• Acorn was a British manufacturer, chosen by the BBC to provide computers for an initiative designed to get as many machines as possible into homes and schools. The original machine had 16 kilobytes of accessible memory, and 32K of solid-state storage. A number of peripherals were available, such as floppy and hard disk drives. They could even be fitted with a network interface. The Acorn came with a pre-installed copy of BASIC, the "Beginner's All-purpose Symbolic Instruction Code." The system was intended to be an introduction to computers and programming, accessible to any new user.
  
  

Commodore

• Commodore's VIC-20 machines were targeted specifically toward home users. At around $300, it was almost half the price of the Acorn. It also had around half the power, but it provided more advanced graphics and sound processors, resulting in its unexpected popularity as a gaming machine. The Sound Interface Device (SID) chip is still sought after by vintage synthesizer enthusiasts, who cannibalize old Commodores to build of custom synthesizers.
  
  

Apple

• In the mid-70s, Steve Wozniak left IBM to form Apple with Steve Jobs. Their first three machines had moderate success amongst hobbyists, but it was the Apple II, released in the early 1980s, that really took off. The company sold 750,000 units by the end of 1982. The graphical user interface was a first, and made the Apple popular with home and business users, who found that they could perform the tasks they wanted without spending months learning how to code. This "accessible to anyone" approach has been one of the main principles of the Apple corporation.
  
  

IBM

• IBM was one of the few giants of corporate computing in the 1970s. It manufactured supercomputers for governments and conglomerates, and was initially skeptical about the market for home computers. As other companies appeared, IBM quickly released the 5120 at the start of 1980. With its integrated monitor and pair of 5.5-inch floppy drives, the 5120 was a record breaker as the heaviest desktop computer ever produced. A complete setup also included an external diskette drive and a wire matrix printer. The 5120 sold 50,000 units in the first half of the 1980s, and the release of the 30lb "Portable PC" in 1984 was an attempt to compete with Compaq's Portable. The IBM Portable was actually just a 5120 in a scaled down case, meaning none of the internal expansion slots could be used. After two or three different versions, and disappointing sales, IBM finally discontinued the Portable line in 1987.