How can I prevent the user of an MVI56-BAS module from modifying the BASIC program while installed on a customer site?

You cannot prevent the user from modifying the BASIC program. However, you can make it more difficult.

1. Write the program and test it in RAM.

2. Use PROG to transfer the program from simulated RAM to ROM 1 of the simulated EEPROM on the CF.

3. Use PROG2 to tell BASIC to automatically execute ROM 1 on power-up.

4. Use NEW to clear the BASIC program out of simulated RAM.

 In order to change the program, the user would have to:

1. Either change the setup jumper to power-up to the BASIC command prompt, or start the program then hit ^C to stop it.

2. Use XFER to transfer the BASIC program to RAM.

3. Use PROG0 to nullify the previous PROG2 command.

4. Use RAM to change the BASIC program pointer to RAM.

5. Now the user can edit the RAM program.