The red and cyan lead-in should produce a clear, steady high pitched note, while the blue and yellow information part gives a much harsher screech.

If you do not hear these noises, then the program was probably not saved. Check that you were not trying to save the program onto the plastic leader at the beginning of the tape. When you have checked this, try saving again.

If you can hear the sounds as described, then SAVE was probably alright and your problem is with reading back.

It could be that you mistyped the program name when you saved it (in which case when NextZXOS finds the program on the tape, it will display the mistyped name on the screen). On the other hand, perhaps you mistyped the program name when you verified it, in which case NextZXOS will ignore the correctly saved program and carry on looking for the wrong name, flashing red and cyan as it goes.

If there is a genuine mistake on the tape, then NextZXOS will display an R Tape loading error which means in this case that it failed to verify the program. Note, that a slight fault on the tape itself (which might be almost inaudible with music) can wreak havoc with a computer program. Try saving the program again, perhaps on a different part of the tape (or a different tape altogether).

MERGE

Many programmers like to store parts of their programs or special subroutines they want to use again and again, thus building libraries of code. Normally a subroutine will be part of a larger program but what if it could be used anew on a different kind of program? Normally you would have to load the entire program into memory, edit out the parts you do not need and then proceed to write the rest of the new program only leaving the part that you want to reuse intact. Similarly, there may be someone that only wants a routine to be used once into their program (for example during initialisation) and then exchange that space for another routine that performs a completely different task. The answer to both these issues is the MERGE command. MERGE is used in the same way as LOAD with the difference that it doesn't clear what's in memory already and does not erase the program's variables and instead only replaces lines that already exist. To illustrate this point consider this little program:

10 PRINT "Part 1"
20 PRINT "Part 2"
30 PRINT "Part 3a"
50 PRINT "Part 5"

Now save the program by giving:

SAVE "part-a.bas"

and then give the command:

NEW

After you re-enter NextBASIC and type LIST you will see there's no program in memory. At that point type:

30 PRINT "Part 3"
40 PRINT "Part 4"
60 PRINT "Part 6"

Now save this program also by giving:

SAVE "part-b.bas"