Figure 5-1: Computer Bus Architectures
BUS ACRONYM	BUS DEFINITION	NUMBER OF BITS	MAXIMUM SPEED (millions of bits/ second, Mbps)
ISA	Industry Standard Architecture	8, 16	1.6
EISA	Extended ISA	8, 16, 32	33
MCA	Micro Channel Architecture	16, 32	33
VESA	Video Electronics Standards Association	32	132
PCMCIA	Personal Computer Memory Card International Association	8, 16, 32	132
PCI	Peripheral Component Interconnect	32, 64	132, 1056
PC/104	(ISA in a smaller, more rugged form factor)	32	132
USB	Universal Serial Bus		12
NuBus	(Macintosh bus)	32	33
PDS	Processor Direct Slot (Macintosh bus)	32	132