Anders Hesselboms teknikblogg

Editing code on the Commodore 65

2010-06-27

The Commodore 64 and the Commodore 128 uses the same method for editing code. You press enter over a line, and that line is stored the with the index of the entered line number, overwriting any existing code on that with that index. The Commodore 65 has the same machine code monitor as the Commodore 128 (it runs more smoothly because the C65 is much faster than the C128). Also, adding and overwriting Basic code is done in the same way. Editing is probably not, but I am not sure.

On the C128, you just had to make sure you saw the line of code on screen, move the text cursor to it, write something else on top of what is there, and save it by pressing Enter. The C65 does not allow you to fly around with the text cursor over the screen. I loved the fact that you could move the cursor to any position, but it was tricky to collect user input if the user suddenly felt the urge to move away and type something unexpected at an arbitrary location. Perhaps they were to implement some command to do this, or perhaps they planned to allow the cursor to move freely. I don’t know.

I have found some great improvements. Here, I have added 4 lines of code. It displays three lines of text and makes a sound. I use the LIST command to display the whole Commodore Basic 10 program.

Already on the C128 you could use arguments to list parts of the program, and change the line numbers throughout the program using the RENUMBER command. But on the C65, you can find out the line number of certain line of code using the FIND command.

The above image shows the C65 telling me where the word HEJ can be found in my program. Also, I can use the CHANGE command to search and replace text. Let’s say I want to change the notes I want the C65 to play, I can use CHANGE to do this. The C65 asks for each search hit before changing.