TABLE OF CONTENTS The personal computer (PC) has been around for a very long time I think that Noah must have had one on his Ark! The first IBM PC was announced in 1981, and since then we ve all wanted to add hardware to our PCs. The power of the PC has grown; the number of tasks we want the PC to accomplish has grown; and the number of devices we want to connect to the PC has grown. But until recently there has been a practical limit on the number of available ports to which we could connect devices.
Enter the Universal Serial Bus, USB. You may have heard USB referred to as the best thing to happen to the personal computer for some time. The list of USB features is impressive:
Hot-pluggable: I/O devices can be added while the PC is running.
Ease of use: I/O device attachment is recognized by the PC and appropriate device drivers, and configuration is done automatically.
Single connector type: all devices plug into the same socket type.
High performance: up to 480 Mbps transfer rate.
Three speed choices: match I/O device speed to one of the standard speeds for optimal design.
Up to 126 devices: there is no practical limit to I/O device expandability.
Power supplied by cable: most devices will not need an additional power source.
Power management: devices automatically power down when not in use.
Error detection and recovery: errors are detected and transactions are retried to ensure that data is delivered...
