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⌂ ∞ Elite on the BBC Micro and NES

Text: DTS_b2

[NES version, Bank 7]

       Name: DTS_b2                                                  [Show more]
       Type: Subroutine
   Category: Text
    Summary: Call the DTS 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:
             * MT18 calls DTS_b2




.DTS_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                 ; bank15
 BEQ bank15

 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 DTS                ; Call DTS, 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

.bank15

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

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