A personal computer released by Atari in 1985. The "ST" stands for "Sixteen/Thirty-two", from the Motorola 68000's 16-bit external bus and 32-bit processor. The original 520ST model had an external floppy drive and power supply whereas the 1040ST had them built-in. The 520 and later 520STFM came with 512 KB of RAM, the 1040 had 1 MB. Several upgraded models followed, up to the 1993 Motorola 68030 based Falcon.