Introduced in 1980 as a business machine, the Apple III was rushed through design and testing into production. Early models were plagued with problems. The IC sockets used could cause the IC chips plugged in to them to pop out while the computer was running. The Apple III was also designed to Apple II compatible. However, the emulation of the Apple II was also lacking. Most of the problems were eventually solved. However the damage had already been done. As result the Apple III failed to achieve anywhere near the success of the Apple II. The Apple III used the 6502A microprocessor that ran at about twice the speed of the 6502 used in the Apple II. The system could be expanded to a maximum of 256K of RAM.