Is there a case that isn't addressed by DOS or AppleSingle headers? The listing files aren't guaranteed to be complete or accurate and some tools don't generate them.

I added an explicit example of DASM building an AppleSingle file (presets/apple2/applesinglebin.a) to this PR.

I then checked the 3 different loadROM paths in apple2.ts. The ones marked // FIXED below did not work previously, but have now been made to work:

1. AppleSingle

   • Sieve (C) loads correctly ($0803), skipping 58 bytes for the header
   • AppleSingle Binary (new DASM example) loads where I tell it, e.g.
     • org $4000 -> 58 bytes skipped, program loaded @ $403a
     • org $4001 -> 58 bytes skipped, program loaded @ $403b

2. 4-byte DOS header

   • DOS 3.3 Binary (previously added DASM example) loads where I tell it, e.g.
     • ORIGIN equ $0803 -> org ORIGIN - 4 is $07ff -> 4 bytes skipped, program loaded @ $0803
     • ORIGIN equ $2000 -> org ORIGIN - 4 is $1ffc -> 4 bytes skipped, program loaded @ $2000
     • ORIGIN equ $2001 -> org ORIGIN - 4 is $1ffd -> 4 bytes skipped, program loaded @ $2001 // FIXED

3. Vanilla BIN

   • HGR Test with (example specified) org $803 -> loads @ $0803
   • HGR Test with ($xx00 address) org $4000 -> loads @ $4000 // FIXED
   • HGR Test with (random address) org $4001 -> loads @ $4001 // FIXED

   Let me know if there are other paths I'm not thinking of.