IBM PS/2 Model 55 SX

Personal System/2 Model 55 SX
	A PS/2 Model 55 SX
Developer	International Business Machines Corporation (IBM)
Manufacturer	IBM
Product family	Personal System/2
Type	Personal computer
Released	May 9, 1989 (Model 55 SX); October 9, 1990 (Model 55 SL);
Lifespan	1989–1992
Discontinued	May 1992
Units sold	Over 1 million
Media	1.44 MB 3.5-in floppy disks (Model 55 SX); None (Model 55 SL);
CPU	Intel 386SX at 16 MHz
Storage	30–80 MB hard drive (Model 55 SX); None (Model 55 SL);
Graphics	Video Graphics Array
Power	120/240 VAC ～
Successor	PS/2 Model 57; PS/2 Model 56; PS/2 Model 53 486SLC2;
Related	List of IBM PS/2 models

The Personal System/2 Model 55 SX is a midrange desktop computer in IBM's Personal System/2 (PS/2) family of personal computers. First released in May 1989, the Model 55 SX features an Intel 386SX processor running at a clock speed of 16 MHz. In October 1990, IBM introduced a diskless workstation version of the Model 55 SX, called the Personal System/2 Model 55 LS. The Model 55 SX was the best-ever selling computer in the PS/2 range, accounting for 23 percent of IBM's PC sales within four months of its introduction. By 1991, the PS/2 Model 55 SX was the best-selling x86-based PC in the world.

IBM succeeded the Model 55 SX with the Personal System/2 Model 57 in 1991, the Personal System/2 Model 56 in 1992, and the Personal System/2 Model 53 SLC2 subfamilies in 1993, with IBM discontinuing the Model 55 SX in mid-1992.