RETURN to the CHEM 498C Home Page

Introduction to Local Area Networks

Chem 498: Computer Interfacing in Chemistry, Spring 1996

Objective: To set up and configure a small low-end local area network (LAN) for the Chem 498C laboratory that will support printer sharing and file service for several client stations. This year we will be setting up a Macintosh LAN based on the AppleTalk protocol running on the built-in LocalTalk hardware ports (which all Macs have), wired together with PhoneNet connectors and wiring, which use low-cost modular telephone cables. (Note that the network protocol, hardware, and wiring are relatively independent. That is, we could have used Ethernet hardware instead of LocalTalk, or Novell protocol rather than AppleTalk, or coax cable rather than telephone wiring. Our choice here is based on availability and low cost, rather than on high performance). We are doing this as the first experiment in the course so that we can use the LAN in the rest or our work.

Equipment required: Macintosh (any models, one running System 7 as the server, the others running System 6 or 7); PhoneNet or other LocalTalk connectors

1. Hardware connections. The LocalTalk port is the DIN-8 socket on the back labeled with a printer icon. (This reflects the fact that the first and widest use of LocalTalk LANs is for printer sharing). Connect a PhoneNet connector to each of the four Mac II client stations, to the Mac IIsi server, and to the Imagewriter dot-matrix printer. The server is the Macintosh IIsi on the right-most desk near the window. Connect all the PhoneNet connectors together with the telephone wires in "daisy-chain" fashion. This will leave two empty phone jack sockets at each end of the chain; terminate them with the termination resistors supplied.

2. Client software. Select one of the four Mac II client stations to be "your" station. Your first task is to prepare an operating system floppy diskette to boot up with. (They have no hard disks, which is one reason we are connecting them all to a LAN). The system floppy must contain at an absolute minimum two files: System and Finder. In addition, in order to access the shared networked printer, they must have the printer driver called AppleTalk Imagewriter. Additionally, in order to be able to access an AppleTalk file server, it must have the AppleTalk file sharing client driver called AppleShare. These are the only required files; optionally, you may also add Sound (to allow you to control the beep-sound and volume), Mouse (to allow you to control the mouse speed and tracking), and General (to allow you to control the RAM cache, desktop pattern, etc). These are all Control Panels, which are accessed via the Control Panels item in the [[apple]] pull-down menu.

All of these files will be found on the hard disk of the Macintosh Performa 475 in a folder labeled "Client boot disk files". Using the box of pre-formatted high-density diskettes provided, prepare two system disks for your client station (one main disk and one back-up). All of the system files should be placed in a folder labeled "System Folder" on your system diskette (use the New Folder command under the File pull-down menu to create a new folder). Label your diskettes "Chem 498C boot disk" and "Chem 498C boot disk backup".

3. Testing printer sharing. Boot up your client station with one of the freshly prepared system disks: press the large key at the top of the keyboard and insert the system disk into the right-most floppy drive (do not use the left floppy drive). Make sure the ImageWriter printer in turned on. At each client station, select Chooser from the [[apple]] pull-down menu. Click on the AppleTalk Imagewriter icon on the left. This causes your client station to poll (interrogate) the LAN for the presence of any printers of that type on the net. Within a few seconds the ImageWriter should respond and its name should appear in the text list field on the right. Click on the name and close the Chooser box by clicking on the small square close box in the upper left corner. Thereafter all printing will be directed to the shared printer. (Of course, only one client can be printing at one time, but the printer sharing allows anyone on the net to print whenever the printer is available, without plugging or unplugging cables or throwing switches).

4. Setting up the server for file sharing. In this network we are going to use the network file sharing capability that is built-in to System 7, the most recent version of the Macintosh operating system. (The client stations are using the earlier System 6, which takes up much less disk space but sill allows the stations to act as clients to a System 7 server).

Read pages 192 - 213 "Sharing your files over the network" in the Macintosh User's Guide, which explains how file sharing works and is set up on the server. Follow the instructions there to turn on file sharing. The name of the file server should be "Chem498C Fileserver".

You and your partner will now take turns at the file server, in order to create a shared folder for your station that you will be able to mount as a remote volume from your client station.

Open the Chem498C Folder, if it not already open, and create a new folder inside of the Chem498C Folder for your client stations and name it accordingly.

Hold down the option key and drag the Microsoft QuickBASIC icon into your new folder.

Select the new folder and choose Sharing... from the File menu. Click on the check box "Share this item and its contents". Set the other check boxes so that Everyone can "see files and folders and make changes". This allows "guest" logins (e.g. without a specifically assigned user name or password) to access that folder.

Close the dialog box and say Yes to the questions about saving the setup.

5. Testing file sharing. Go back to your client station and read pages 185 - 190 "Gaining access to files on other computers" in the Macintosh User's Guide. Follow these instructions to select the "Chem498C Fileserver", then select the shared folder that you created for your station on the file server and log on as a "guest" (rather than a registered user). An icon should appear in the grey desktop right under the icon of the system floppy disk. This icon represents the remote shared folder on the file server. Open it. It should contain a copy of Microsoft QuickBASIC. Launch (double-click) on it.

Type PRINT "Hello, world." into the edit window on the right and print it (select Print from the File menu) to test the printer. Save the file (select Save from the File menu). Verify that the file has indeed been saved in the folder you created on the file server.

Questions and Experiments

1. How do you think it is possible for the network to distinguish between the four client stations, when they all log on a "guest" and have identical system boot disks? How are they different?

2. Is it possible to print to the network printer and to access a file from the file server at the same time? Try it.

3. What happens if two stations attempt to print a file at the same time?

4. See if you can notice an increase in the time it takes to launch Microsoft QuickBASIC when all four client stations launch the program simultaneously, compared to the time it takes to launch from one station alone with no other network activity.

6. See if you can figure out, from the Macintosh User's Guide, how to create a private folder that you alone can access as a "registered user". (You will have to go the the server to create this folder and assign yourself a user name and password, then log on from your client station as a registered user).

This page is maintained by Tom O'Haver , Department of Chemistry and Biochemistry, The University of Maryland at College Park. Comments, suggestions and questions should be directed to Prof. O'Haver at to2@umail.umd.edu.