The Apple III was manufactured and sold by Apple from May, 1980 until its discontinuation on April 24, 1984. Intended as a computer for the business user market, design work on the Apple III started in late 1978 under the guidance of Dr. Wendell Sander. It had the internal code name of "Sara", named after Sander's daughter.
The Apple III was designed to be a business computer and a successor for the Apple II. It featured an advanced operating system called Apple SOS, or "Sophisticated Operating System", pronounced "Apple Sauce" and a new BASIC interpreter, "Apple /// Business BASIC" (an implementation of UCSD Pascal was also offered for more structured programming). Other features included an 80-column display with upper and lowercase characters, a numeric keypad, support for a real-time clock, 6-bit (DAC) audio, 16-color graphics, and a hierarchical file system. It included a built-in 140 KB 5.25" floppy disk drive, with up to three additional external "Disk ///" floppy disk drives, which were only compatible with the Apple ///. In addition they required an adapter for use on the /// Plus. Originally intended as a direct replacement to the Apple II series, it was designed for backwards-compatibility of Apple II software in order to migrate users over. However, since Apple did not want to encourage continued development of the II platform, they limited its capabilities to emulate a basic 48 KB Apple II+ configuration, with no access to the III's advanced features, a restriction which actually required custom chips to enforce.
The Apple III was powered by a 2 MHz SynerTek 6502A 8-bit CPU and, like some of the more advanced machines in the Apple II family, used bank switching techniques to address up to 256 KB of memory (512 KB with a third-party upgrade).
The Apple III was the first Apple product that allowed the user to choose both a screen font and a keyboard layout:either QWERTY or Dvorak. These choices could not be changed while programs were running, unlike the Apple IIc, which had a keyboard switch directly above the keyboard, allowing switching on the fly.
For a variety of reasons, the Apple III was a commercial failure. With a starting price between $4,340 to $7,800 US, it was more expensive than many of the CP/M-based business computers that were available at the time. The Apple III's software library was very limited, and while sold as an Apple II compatible, the emulation that made this possible was intentionally hobbled, thus it could not make use of the advanced III features (specifically 64 KB RAM or higher, required by a large number of Apple II software titles based on PASCAL), which limited its usefulness.
Far more importantly, the machine was plagued by numerous hardware and software bugs. The real time clock, the first in an Apple computer, would fail after prolonged use. This chip, which was made by National Semiconductor, was an example of a recurrent problem. Semiconductor purchase contracts allowed a vendor 30 days to replace defective parts. It was assumed that a vendor would test parts before shipping them, but this was not required. National had a reputation for knowingly shipping bad parts, confident that they could do another production run before they had to send replacements. This was not a problem for customers who put chips in sockets and had extensive repair facilities. However, Apple was soldering chips directly to boards and could not easily test a board to find a single bad chip. Eventually, Apple solved this problem by deleting the real-time clock from the specification, rather than putting in a working clock chip.