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⌂ ∞ ▽ Elite on the 6502

Drawing the screen: DrawBackground_b3

[NES version, Bank 7]

       Name: DrawBackground_b3                                       [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Call the DrawBackground routine in ROM bank 3
  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:
             * DrawCmdrImage calls DrawBackground_b3
             * DrawSystemImage calls DrawBackground_b3




.DrawBackground_b3

 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 #3                 ; Page ROM bank 3 into memory at $8000
 JSR SetBank

 JSR DrawBackground     ; Call DrawBackground, 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