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⌂ ∞ ▽ Elite on the 6502

Text: CHPR_b2

[NES version, Bank 7]

       Name: CHPR_b2                                                 [Show more]
       Type: Subroutine
   Category: Text
    Summary: Call the CHPR routine in ROM bank 2
  Deep dive: Splitting NES Elite across multiple ROM banks

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * ChangeLetter calls CHPR_b2
             * InputName calls CHPR_b2
             * PrintFlightMessage calls CHPR_b2




.CHPR_b2

 STA storeA             ; Store the value of A so we can retrieve it below

 LDA currentBank        ; If ROM bank 2 is already paged into memory, jump to
 CMP #2                 ; bank22
 BEQ bank22

 PHA                    ; Otherwise store the current bank number on the stack

 LDA #2                 ; Page ROM bank 2 into memory at $8000
 JSR SetBank

 LDA storeA             ; Restore the value of A that we stored above

 JSR CHPR               ; Call CHPR, now that it is paged into memory

 JMP ResetBank          ; Fetch the previous ROM bank number from the stack and
                        ; page that bank back into memory at $8000, returning
                        ; from the subroutine using a tail call

.bank22

 LDA storeA             ; Restore the value of A that we stored above

 JMP CHPR               ; Call CHPR, which is already paged into memory, and
                        ; return from the subroutine using a tail call