Universal Serial Bus Specification Revision 1.1
1
Chapter 1
Introduction
1.1 Motivation
The motivation for the Universal Serial Bus (USB) comes from three interrelated considerations:
Connection of the PC to the telephone
It is well understood that the merge of computing and communication will be the basis for the next
generation of productivity applications. The movement of machine-oriented and human-oriented data
types from one location or environment to another depends on ubiquitous and cheap connectivity.
Unfortunately, the computing and communication industries have evolved independently. The USB
provides a ubiquitous link that can be used across a wide range of PC-to-telephone interconnects.
Ease-of-use
The lack of flexibility in reconfiguring the PC has been acknowledged as the Achilles’ heel to its
further deployment. The combination of user-friendly graphical interfaces and the hardware and
software mechanisms associated with new-generation bus architectures have made computers less
confrontational and easier to reconfigure. However, from the end user’s point of view, the PC’s I/O
interfaces, such as serial/parallel ports, keyboard/mouse/joystick interfaces, etc., do not have the
attributes of plug-and-play.
Port expansion
The addition of external peripherals continues to be constrained by port availability. The lack of a bidirectional,
low-cost, low-to-mid speed peripheral bus has held back the creative proliferation of
peripherals such as telephone/fax/modem adapters, answering machines, scanners, PDA’s, keyboards,
mice, etc. Existing interconnects are optimized for one or two point products. As each new function
or capability is added to the PC, a new interface has been defined to address this need.
The USB is the answer to connectivity for the PC architecture. It is a fast, bi-directional, isochronous,
low-cost, dynamically attachable serial interface that is consistent with the requirements of the PC
platform of today and tomorrow.
The PS/2 device interface, used by many modern mice and keyboards, was developed by IBM and originally
appeared in the IBM Technical Reference Manual. However, this document has not been printed for many
years and as far as I know, there is currently no official publication of this information. I have not had access
to the IBM Technical Reference Manual, so all information on this page comes from my own experiences as
well as help from the references listed at the bottom of this page.
PS/2 设备接口用于许多现代的鼠标和键盘它是由IBM 开发并且最初出现在IBM 技术参考手册里但
是当我知道的时候这篇文件就已经很多年没有印刷了因此关于这个内容现在没有官方的出版物我
无法访问IBM 的技术参考手册所以本网页中的所有信息都来自于我自己的经验及本页最下面列出的
参考的帮助
