The program EDL (Electron Data Link) is a much modified version of Watford Electronics' BBC-Z88 data transfer software which has the restriction of only working on a BBC connected to a Z88 and in Mode 7. With more portable computers on the market these days (eg the Amstrad NC10 0 or 200), more and more people will wish to transfer their data to and from such machines. With this is mind I set about trying to produce an easy to understand file transfer utility.

For the utility to work, you will require an RS423 interface. I believe Slogger and Pres produced these add-ons.

The BBC/Z88 program provided a good starting point but there were many changes to be made, such as:

1. Improve the menu layout
2. Additional key presses (Short cuts) to select options
3. Each character is displayed on screen as it is sent or received in 80 column format
4. The ability to add or remove Line Feeds from the displayed data (similar to the double line spacing or over-write effects on a printer)
5. Character count is displayed after transfer is complete
6. Work in Modes 6 and 7 with DFS and/or ADFS
7. Make it compatible with many more computers - probably not the Z88 though

After all that, there is very little left of the original program and I think I have made it as simple to use as possible i.e. no messing around with Start & Stop Bits etc. by using the Electron default settings.

At this point, I would like to thank Roy Warner for his articles on Assembly language programming in previous issues of EUG. Without these I would probably never have ventured into this area - I struggle enough with BASIC!

How to use the program

To RUN the Data Transfer program, select it from the menu or CHAIN the file U.EDL in the normal way. A menu will be presented to you with five options:

                    (R)eceive
                    (S)end
                    (I)nbound CR/LF ON
                    (O)utbound CR/LF ON
                    (Q)uit

Select your option by using the UP or DOWN cursor keys or by pressing R, S, I, O or Q.

Receive - When 'Receive' is selected you are asked for a filename to store your data in. Enter a filename then press RETURN. The computer will open a file on the disk and wait for the incoming data.

Now send the data from your source computer. As each character is received, it is displayed on screen in 80 column mode and on completion, the computer will close the file and display in the bottom right corner of the screen, the total characters received. After a short delay you are returned to the menu.

Send - When 'Send' is selected you are asked for the filename of your source text. Enter a filename and before pressing RETURN set up the receiving computer to receive your data.

The computer will now open the file, and as each character is sent it is displayed on screen in 80 column mode. At the end of transmission the computer will display, in the bottom right corner of the screen, the total characters sent. After a short delay you are returned to the menu.

Inbound CR/LF (CR = Carriage Return, LF = Line Feed) - This is normally set to ON which means that when a CR code is received, it will append a LF code when the character is sent to the screen forcing the cursor on to a new line. Some computers will send both a CR and a LF code so the option is there to remove the LF appended by the Electron. Pressing I or RETURN on this option toggles between CR/LF ON and OFF.

Outbound CR/LF - This is normally set to ON meaning that when sending a CR code, it will append a LF code when it is sent to the screen, forcing the cursor onto a new line. Some files may have LF codes present so the option is there to remove the one appended by the Electron. Pressing O or RETURN on this option toggles between CR/LF ON and OFF.

Notes

• View files do not have the LF code present so the default setting is on. The I and O option only affects the screen and not the contents of the file.
• Return to BASIC by pressing Q.
• * commands can be issued from the main menu.
• To overcome the problem of sending BASIC programs to other computers, simply *SPOOL the program and *EXEC it back to BASIC once stored in the destination computer.
• The Serial interface is set to the default settings of the Electron computer and shouldn't need to be altered:

  Start Bits	1	Stop Bits	1
  Data Bits	8	Baud Rate	9600

  In the unlikely event that they do need changing, they can be by listing line Numbers 530 to 590 and changing the *FX values. See your RS423 Peripheral User Guide or the BBC User Guide for the new values.

Derek Walker, EUG #12