Skip to navigation

⌂ ∞ ▽ Elite on the 6502

Drawing the screen: DrawScreenInNMI_b0

[NES version, Bank 7]

       Name: DrawScreenInNMI_b0                                      [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Call the DrawScreenInNMI 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:
             * PAUSE calls DrawScreenInNMI_b0
             * PAUSE2 calls DrawScreenInNMI_b0
             * UpdateSaveScreen calls DrawScreenInNMI_b0




.DrawScreenInNMI_b0

 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

 JSR DrawScreenInNMI    ; Call DrawScreenInNMI, 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