The PROT3 (Loader) subroutine - Elite on the BBC Micro and NES

       Name: PROT3                                                   [Show more]
       Type: Subroutine
   Category: Copy protection
    Summary: Part of the CHKSM copy protection checksum calculation
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * Elite loader (Part 1 of 3) calls PROT3


.PROT3

 LDA CHKSM              \ Update the checksum
 AND CHKSM+1
 ORA #&0C
 ASL A
 STA CHKSM

 RTS                    \ Return from the subroutine

                        \ --- Mod: Code removed for Elite-A: ------------------>

\ JMP P%                \ This would hang the computer, but we never get here as
\                       \ the checksum code has been disabled

                        \ --- End of removed code ----------------------------->

Copy protection: PROT3

[Elite-A, Loader]