Serial Networking: The Alternatives

As I have illustrated in the Pros and Cons section, Serial Networking is not ideal. If you are just wanting to transfer files then the Ethernet compatability of the method is unecessary. In this case, you might want to look at other alternatives which offer file transfer at a faster rate.

In order to achieve a faster transfer rate, without having to resort to the full Ethernet solution, we have to use a parallel cable. There are two networking solutions that use parallel cable, as far as I am aware: ParaFS and ZeriLink. (NB. Both require the host computers to have bi-directional parallel ports, so only A5000's or later will be suitable.)

ParaFS is a commercial package produced by Stuart Tyrrell Developments: http://www.stdevel.com/. It can only be used for linking RISC OS computers, but has the advantage of a GUI based shared drive system, similar to the Windows File Sharing system. It can also be supplied with the special parallel cable, if required. It is certainly the most user friendly parallel networking option, so may be suited to those less experienced users.

ZeriLink is a freeware package produced by John Kortink, which is available for download from his website: http://www.inter.nl.net/users/J.Kortink/ . It can be used for linking a RISC OS computer to either another RISC OS computer or a Windows PC, and also linking two Windows PC's.

ZeriLink is essentially command line based, which may discourage less experienced user, and it does not have the same shared drive capability as ParaFS. However, using Obey files on your RISC OS computer or BAT files on your Windows PC we can avoid direct command line interaction.

First of all we need to get a suitable cable. The diagram below shows the pin to pin wiring of the cable:

You can also download the full size diagram as a:

26 KB GIF image
5 KB Zipped Drawfile

If you are fairly confident with a soldering iron then you could make the cable yourself, I constructed one for about £10. The ingredients for the cable are:

• 2x 25 way D plugs
• 2x plastic covers for the D plugs
• 25 way shielded cable. Remember to attach the cable shielding to the metal casing of the D plugs. (The maximum recommended length for parallel cable is 3 metres, in order to avoid signal corruption)
• Some wire to link pins 13 and 15 on each plug

If you don't feel happy about making the cable, then ask your local computer shop to make it for you. Be prepared to pay a bit extra for the privilege though.

Now that we have the hardware, we need to install the software:

You need two files from the ZeriLink distribution: The ZLink module and the LinkConf text file. It is recommended that the ZLink module is loaded in the Boot sequence, so place it in the Boot.Choices.Boot.PreDesk folder. In order to configure the module we need the LinkConf configuration file, which I recommend to be placed in the Boot.Choices directory, inside a new directory called ZeriLink. In order to make ZeriLink read the file, create an Obey file called ~ZLink containing the following line, saved in the Boot.Choices.Boot.Tasks directory:

LinkConfigure Boot:Choices.ZeriLink.LinkConf

You may need to change the content of the configuration file depending on the computer model you are using. Zerilink can be configured to use either a bi-directional or ECP parallel port. If you have a A5000, A3010, A3020, A4000 or A4 you will have to use bi-directional. Newer RISC OS computers can use the faster ECP standard. The part of the configuration file which needs to be modified is shown below:

;
; Mode <mode>
; -----------
; Receive and transmit. Set link mode to <mode> (ECP or BIDIR). The
; other side should be set to the same link mode. The default link
; mode is BIDIR.
;

Mode ECP

Now that we have installed the software we can create a more user friendly interface to Zerilink:

• Create a new directory called ZeriLink somewhere on your hard drive. For this example, we will use the following directory path: ADFS::HardDisc4.$.Networking.ZeriLink
• Within this directory, create two new directories called Receive and Send.
• Use your favourite text editor to create an Obey file containing the following text:
  Dir ADFS::HardDisc4.$.Networking.ZeriLink.Receive
  LinkR
  Save this file, in the ZeriLink directory, with the filename: Receiver
• Create another Obey file in the Zerilink called Sender, containing the following text:
  linkt ADFS::HardDisc4.$.Networking.ZeriLink.Send.*
  wipe ADFS::HardDisc4.$.Networking.ZeriLink.Send.*

The ZeriLink directory should look like the screenshot below:

ZeriLink is now ready for use on your RISC OS computer.

PC Configuration:

• Create a new directory called ZeriLink somewhere on your hard drive. For this example, we will use the following directory path: C:\Program Files\ZeriLink
• Into this directory place the following files from the ZeriLink archive: Linkr.exe, Linkt.exe & Link.cnf. You may need to edit the contents of the Link.cnf file in a text editor, depending on what parallel port you have on your RISC OS machine. Do this in the same way as described for the RISC OS ZeriLink configuration file.
• In the ZeriLink directory, create a new directory called Send.
• Use a text editor to create a .BAT file containing the following text:
  Linkt C:\Progra~1\ZeriLink\Send\*.*
  Save this file in the ZeriLink directory with the filename: Sender.bat

The ZeriLink directory should look like the screenshot below:

Using ZeriLink:

Sending a file from your RISC OS to PC computer: Place the files you want to send into the Send directory on your RISC OS computer. Run the Linkr.exe application on your PC and then run the Sender file on your RISC OS machine. The file/s will be transferred to the ZeriLink directory on your PC and you will be prompted whether you want to delete the copy of the file/s on your RISC OS computer. Note that this will cause your RISC OS computer to single task until the transfer is complete.

Sending a file from your PC to RISC OS computer: Place the files your want to send into the Send directory on your PC computer. Run the Receiver file on your RISC OS computer and then run the Sender.bat file on your PC. The file/s will be transferred to the Receive directory on your RISC OS computer.