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⌂ ∞ Elite on the BBC Micro and NES

Text: CHPR (Part 4 of 6)

[NES version, Bank 2]

       Name: CHPR (Part 4 of 6)                                      [Show more]
       Type: Subroutine
   Category: Text
    Summary: Process the delete character
  Deep dive: Fonts in NES Elite

    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file




.chpr21

                        ; If we get here then we are printing ASCII 127, which
                        ; is the delete character

 JSR GetRowNameAddress  ; Get the addresses in the nametable buffers for the
                        ; start of character row YC, as follows:
                        ;
                        ;   SC(1 0) = the address in nametable buffer 0
                        ;
                        ;   SC2(1 0) = the address in nametable buffer 1

 LDY XC                 ; Set Y to the text column of the text cursor, which
                        ; points to the character we want to delete (as we are
                        ; printing a delete character there)

 DEC XC                 ; Decrement XC to move the text cursor left by one
                        ; place, as we are deleting a character

 LDA #0                 ; Zero the Y-th nametable entry in nametable buffer 0
 STA (SC),Y             ; for the Y-th character on row YC, which deletes the
                        ; character that was there

 STA (SC2),Y            ; Zero the Y-th nametable entry in nametable buffer 1
                        ; for the Y-th character on row YC, which deletes the
                        ; character that was there

 JMP chpr17             ; Jump to chpr17 to return from the subroutine, as we
                        ; are done printing this character