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Micro House PC Hardware Library Volume II: Network Interface Cards And Modems Micro House PC Hardware Library Volume II: Network Interface Cards And Modems
by Micro House International, Inc. and Scott Mueller
Que, Macmillan Computer Publishing
ISBN: 078971664x   Pub Date: 06/17/98
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USB (Universal Serial Bus)

The USB was designed as a convenient method to connect a variety of different peripherals to a system. Intel has been the primary proponent of USB, and most of their new PC chipsets, starting with the Triton II (82430HX and VX), will include USB support as standard. Six other companies have worked with Intel in co-developing the USB, including Compaq, Digital, IBM, Microsoft, NEC, and Northern Telecom. Together these companies have established the USB Implementers Forum to develop, support, and promote the USB architecture.

The USB is a 12Mbit/sec (1.5M/sec) interface over a simple 4-wire connection. The bus supports up to 127 devices and uses a tiered star topology built on expansion hubs that can reside in the PC, any USB peripheral, or even stand-alone hub boxes. For low-performance peripherals such as pointing devices and keyboards, the USB also has a slower 1.5Mbit/sec subchannel.

USB also conforms to Intel’s Plug and Play (PnP) specification, including hot plugging, which means that devices can be plugged in dynamically without powering down or rebooting the system. Simply plug in the device, and the USB controller in the PC will detect the device and automatically determine and allocate the resources and drivers required. Microsoft has USB drivers developed and have included them in existing versions of Windows 95 and NT. USB support will also be required in the BIOS, which will be included in newer systems with USB ports built in. (USB is built into Windows 98 and the OSR2 version of Windows 95. For earlier versions of Windows 95, USB support is available as a download from Microsoft’s Web site.)

Aftermarket USB boards will be available for adding USB to an existing system. Such boards will likely have ROM on-board, which will allow the USB peripherals to function under DOS, while Windows built-in drivers will take care of the USB function under Windows.

USB peripherals will include modems, telephones, joysticks, keyboards, and pointing devices such as mice and trackballs.

One interesting feature of USB is that all attached devices will be powered by the USB bus itself. The PnP aspects of USB allows the system to query the attached peripherals as to their power requirements and issue a warning if available power levels are being exceeded. This will be important for USB when used in portable systems, because battery power to run the external peripherals may be limited.

Understanding the Components of a LAN

A local area network (LAN) enables you to share files, applications, printers, disk space, modems, faxes, and CD-ROM drives; use client/server software products; send electronic mail; and otherwise make a collection of computers work as a team.

In today’s world, there are many ways to construct a LAN. A LAN can be as simple as two computers connected together via either their serial or parallel ports. This is the simplest and probably the most common LAN today. Many users connect their laptop to their desktop computer for access to a printer or to transfer files. This type of connection is usually called a direct cable connection, in which one computer is designated as the host computer. The host computer is the machine with the resources you want to access. The guest computer wants to use the resources of the host. You can purchase software that allows you to connect two computers in this manner, but some operating systems such as DOS and Windows 95 have direct cable connection support built in. Although the term network is not often used for this sort of arrangement, it does satisfy the definition.

Peer-to-peer networks have become more popular as the software became more reliable and personal computers became more powerful. Peer-to-peer means computer to computer. In a peer-to-peer network, any computer can access any other computer to which it is connected and has been granted access rights. Essentially, every computer functions as both a server and a client. Peer-to-peer networks can be as small as two computers, or as large as hundreds of units, and they may or may not use a LAN card or network interface card (NIC). For more than two stations, or when higher data transfer speeds are desired, NICs should be used.

Peer-to-peer networks are more common in small offices or within a department in a larger organization. The advantage of a peer-to-peer network is that you don’t have to dedicate a computer to be a file server. Most peer-to-peer networks allow you to share practically any device attached to any computer. The potential disadvantages to a peer-to-peer network are that there is typically less security and less control.

Windows 95 has peer-to-peer networking built in. With Windows 95, setting up a peer-to-peer LAN can be accomplished in two ways. The first method is to install the dial-up networking modules. Dialup networking requires a Windows 95-compatible server, such as Windows 95 dial-up server in the Plus! package, or Windows NT. Dial-Up Networking allows the remote system (the one dialing in) to access the server and any peripherals attached to the server to which the remote user has been given rights. These peripherals can be CD-ROM drives, tape drives, removable media drives, hard drives, and even another network as long as it is an IPX/SPX or NetBEUI network. IPX/SPX are the network transport protocols used in NetWare and other networks. NetBEUI is the NetBIOS (Network Basic Input Output System) Extended User Interface; it is the native protocol of Microsoft Windows networks.

The other method of peer-to-peer networking is much like that with which we all became familiar in Windows for Workgroups, but it is much easier to set up in Windows 95. With the new PnP technology incorporated into the operating system, most NICs are automatically detected. Supported NIC manufacturers include 3COM, Digital Equipment Corporation, IBM, Intel, Madge, Novell, Proteon, Racal, SMC, and Thomas-Conrad. Once the NIC is detected, Windows 95 asks for a computer name and a workgroup name. Once this is accomplished, your Windows 95 network workstation is ready to go.

A LAN is a combination of computers, LAN cables (usually), network adapter cards, network operating system software, and LAN application software. (You sometimes see network operating system abbreviated as NOS.) On a LAN, each personal computer is called a workstation, except for one or more computers designated as network servers. Each workstation and server contains a network adapter card. LAN cables connect all the workstations and servers, except in less frequent cases when infrared, radio, or microwaves are used.


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