Computer on Basis of Brand

Type	Full Name	Introduced	Developed By	Example System	Processor	Input	Output	Storage	Architecture	Purpose	Creation Method	Used Until	Advantages	Disadvantages
XT	Extended Technology	1983	IBM	IBM PC/XT	Intel 8088	Keyboard	Monitor, Printer	Floppy disk, Hard disk	8-bit ISA slots	Improve early PCs and allow hardware expansion	Improved motherboard with expansion slots	Late 1980s	Simple, expandable, first widely used business PC	Slow speed, limited memory
AT	Advanced Technology	1984	IBM	IBM PC/AT	Intel 80286	Keyboard	Monitor, Printer	Hard disk, Floppy disk	16-bit ISA slots	Increase speed and memory capacity	New motherboard with better processor and RAM support	Early 1990s	Faster CPU, larger RAM support	Larger size, higher power consumption
PS/2	Personal System/2	1987	IBM	IBM Personal System/2	Intel 80386 / Intel 80486	Keyboard, Mouse	Monitor, Printer	Hard disk, Floppy disk	Micro Channel Architecture (MCA)	Create modern standardized PC systems	Redesigned PC architecture with new ports	Mid 1990s	Better performance, introduced PS/2 ports	MCA architecture expensive and not widely adopted