The Atari 8-bit family is a series of 8-bit home computers introduced by Atari, Inc. in 1979 and manufactured until 1992. All of the machines in the family are technically similar, and differ primarily in packaging. They are based on the MOS Technology 6502 CPU running at 1.79 MHz and were the first home computers designed with custom co-processor chips. The original Atari 400 and 800 models were released with a series of plug-n-play peripherals that used Atari's "SIO" serial bus system. Over the following decade, the original models were replaced by the XL and XE series which had the same basic logical design, but were of much lighter construction and less expensive to build.