Unfortunately S&SC listings are notoriously bad - I think they typed them back in my hand into their DTP package so there are errors. I've fixed up a bunch of them in the assembler listing in order for it to compile. Specifically for prosperity they are:
- Correct LOADDRV and SAVEDRV EQU labels to LODDRV and SAVDRV as per their references in the code
- Correct DEFN to DEFM for MENU4 catalogue label
- Correct ERMSG to ERRMSG
- Correct RAMERR to RMMERR
- Correct LD,A(H) to LD(HL)
The code compiles and merges with the RAM Music Machine software and indeed provides a working 'catalogue drive' option and save seems to work fine but LOAD is not working.
I'm not sure yet if that's an error in the listing or maybe the RAM Music Machine software on WOS is a different version. (The author mentions it works with 'the latest version' but doesn't specify what version that is - nor does the software show a version number I can see)
Once I get that working I'll update the listing and put together a +3 DSK containing the patched software. Unfortunately no emulators support the RAM Music Machine (why!?) and I don't have one to test.