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⌂ ∞ ▽ Elite on the 6502

Drawing the screen: TT66_b0

[NES version, Bank 7]

       Name: TT66_b0                                                 [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Call the TT66 routine in ROM bank 0
  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:
             * ChooseLanguage calls TT66_b0
             * HALL calls TT66_b0
             * MT9 calls TT66_b0
             * PAUSE calls TT66_b0
             * SVE calls TT66_b0




.TT66_b0

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

 LDA currentBank        ; Fetch the number of the ROM bank that is currently
 PHA                    ; paged into memory at $8000 and store it on the stack

 LDA #0                 ; Page ROM bank 0 into memory at $8000
 JSR SetBank

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

 JSR TT66               ; Call TT66, 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