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Connecting Two Macs With a Serial Connection

Category: 68K , Classic Mac OS , Networking
Composed by: that-ben
On: 2017-11-25 17:08:32
Updated by: that-ben
On: 2017-11-25 17:10:58

Jag's World Header Mad With Macintosh


Connecting Two Macs With a Serial Connection



  1. Introduction
    1. Pros
    2. Cons
  2. Procedure
    1. Requirements
    2. Setting Up The Connection
    3. Setting Up File Sharing
    4. Seeing The Other Mac
  3. Troubleshooting
  4. What Next?
  5. Disclaimer




One of the best things about Macs is that they all come with built in networking capabilities. This can take the form of an ethernet card but many older Macs don't have this. However, all Macs have a modem and printer serial port and it is very easy to just take a printer cable, stick it into the printer ports of each Mac, set up file sharing and you're away! This page is designed to help you with that task.


Why would you want to connect two Macs in this way? Here are a few ideas:

  • If you have ever bought a new Mac then you will know that all you have to do is plug it in and you're away. However, you will also know that although everything works fine, it takes a while to go through the process of transferring all of your applications and work from your old Mac. If you are unfortunate enough to only have a floppy disk drive, this process will take you forever. By networking two Macs, you can simply copy stuff from one hard drive to another by dragging and dropping. Admittedly this is a bit slow but you can just leave it going overnight and in the morning, hey presto!, your lovably customised old Mac has been transplanted into your new one. However, you really should install your applications from the original disks as often applications have essential files in the system folder rather than the application folder.
  • You may have a desktop Mac with a CD-ROM drive and a PowerBook without one. By networking the Macs together your PowerBook can access the CD-ROM drive.
  • If you have a crusty old LC then why not use its hard drive as extra storage space?
  • Network gaming works well with this method.


There are a few reasons why you shouldn't use the printer cable method:

  • If you find that you are networking your Mac a lot in this way, you should consider getting a proper AppleTalk connection kit or an ethernet connection. These aren't very expensive and will save wear and tear on your printer port with all of the inserting and removing of cables. Another advantage is that the kit is electrically isolates the two Macs which brings me to my second point.
  • In theory it is possible to do damage to the computers because the cable does not isolate the computers from eachother. What this means is that if there is a damaging power surge, rather than just losing the one computer, you will lose both. On the other hand, how many times have you had your Mac damaged by a power surge?
  • It is slow. I usually equate it to about the speed of a floppy disk. However, it does have the advantage that you can leave it alone while you do something else and it is free. If you want to network your computers more quickly you should invest in an ethernet connection.





Now we're past all of the pros and cons, it is time to actually get on with connecting the Macs together.


You need:

  1. A printer cable like the ones which come with StyleWriters etc.
  2. All of the networking software described below. If you are unsure if you have it or not, get your system disks and custom install the Networking Software. If you have followed all of the instructions here and you can't get it to work, something is probably missing.

However, there are two types of networking software - Open Transport and the traditional networking software. Fortunately, they process is very similar for both but I will describe them separately. If one Mac is using OT and the other isn't, you can still network them. Just follow the instructions for your computer.


Setting up the connection

Open Transport

  1. Insert the printer cable into your Mac's printer port (the modem port will also work, just read 'modem port' instead of 'printer port')
  2. Open the AppleTalk control panel. It will ask you if you want AppleTalk turned on if it isn't already active, click 'Yes'.

Appletalk CP

  1. Select 'Printer Port' in the connect via menu.
  2. Close the AppleTalk CP.

Your Mac is now ready for file sharing.

Traditional Networking

  1. Insert the printer cable into your Mac's printer port.
  2. Open the Network control panel and select "AppleTalk"
  3. Then click on the printer port icon.
  4. Close the Network CP
  5. Open the Chooser

The Chooser

  1. Click on the AppleTalk Active button.

Your Mac is now ready for file sharing


Setting up File Sharing

Fortunately this process is identical for both pieces of software. Note that if you simply want a network connection to link two applications (eg. games, FileMaker Pro databases) you already have that connection. File Sharing allows you to share files, it is one use you can make of the connection you have made.

  1. Open the Sharing Setup control panel

Sharing Setup Control Panel

  1. Fill in the Owner Name, Owner Password and Macintosh name boxes.
  2. Select 'Start File Sharing'
  3. File sharing is now set up on your Macintosh but you still want the other person to see your files so you have to share them.
  4. Select the folder you want to share (this may be your Hard Drive) and select 'Sharing' in the File Menu.

File Sharing CP

  1. Click on the 'Share this file and its contents' checkbox.
  2. The folder is now shared. Note that you can change your access privileges in many ways but this sort of security is not really needed with a two way connection. It is easiest to make access as full as possible. If you really want to play around with this, you also need the 'Users & Groups' CP but I will not go into that here.


Seeing the Other Mac

At this stage, both Macs should have gone through the same process and should be at the same point. It is quite possible to only set up sharing on one Mac and then connect with the other though.

  1. Open the Chooser and select AppleShare
  2. You should now see the other Mac's hard drive appear in the 'Select a File Server' box. If it doesn't then either the connection is not set up properly or file sharing isn't set up properly. Go back and check through the instructions.
  3. Double click on the File Server you want (as you would logging into Thompson)
  4. You will be prompted for a username and password. Enter the owner name and owner password here. You can connect as a guest if you set up the host computer correctly. To do this, open the Users & Groups CP, select guests and select the 'Allow guests to Connect' button. You must also allow guests access to your hard drive. It is easier to log in as the owner leaving the password blank though.

Users & Groups CPGuests


  1. Now another Hard Drive icon should appear on your screen. When opened it will operate exactly as if you were looking at your own hard drive.

These are just the very basics of file sharing. There is a whole lot more but this was designed primarily as an introduction to networking two Macs rather than a guide to becoming a network manager. If you want to play around some more then use the AppleGuide which is very helpful in this respect. It can be quite fun to play network managers by creating users and groups, changing access privileges etc as it reminds you how easy to use the Mac is, even for something as complicated as networking.





So, you've gone through all of the instructions but it still wont work. Here is a list of things that may have gone wrong:

  • Not all of the software you need is installed. Check in your Disabled Extensions to see if they are in there first and also do a search if you know what isn't present (eg. AppleShare or a CP). If you have never used the networking software before it is quite likely that you have deleted it all thinking that you'll never need it. Just install it again. If all of the obvious things are there, you still may have deleted something obscure like the library files OT needs.
  • Check that you are actually using the port you have set up for. It is very easy to have the wrong port selected and spend ages fruitlessly reinstalling software.
  • Ensure that the privileges are set up correctly. This will be the reason for any problems once actually connected.
  • You may find that your Mac 'hangs' occasionally while connected. This is not actually a crash but just the network taking its toll. You can tell if it is the network because there will be a pair of arrows in the top left of the screen flashing.




What Next?

What else can you do with this feature?

  • You can use file sharing over a modem. This involves either using AppleTalk Remote Access which actually comes free with some systems or a shareware alternative such as Netlink Remote.
  • You can use file sharing over the internet using a piece of shareware such as TCPSerial.
  • You can remote control a Mac using applications that utilise program linking.
  • Access CDs by sharing them in the same way as you share the Hard Drive.



If in following the advice contained herein, damage is caused to a computer, it is the sole responsibility of the owner of the computer and no other person or institution.


©1996-04 JagWerks Media

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