# ip65 technical reference

# File : drivers/a2print.s

## functions

function | description
--- | ---

beep

    use Apple 2 monitor ROM function to move to make a 'beep' noise
    inputs: none
    outputs: none

cls

    use Apple 2 monitor ROM function to move to clear the screen
    inputs: none
    outputs: none

print_a

    use Apple 2 monitor ROM function to display 1 char
    inputs: A should be set to ASCII char to display
    outputs: none

print_a_inverse

print_cr

    use Apple 2 monitor ROM function to move to new line
    inputs: none
    outputs: none

## constants

constants | description | value
--- | --- | ---
screen_current_col | CH - Horizontal cursor-position (0-39) | $24
screen_current_row | CV - Vertical cursor-position (0-23) | $25

## implementation

    .export print_a
    .export print_a_inverse
    .export print_cr
    .export cls
    .export beep
    .exportzp screen_current_row
    .exportzp screen_current_col

    .code

    screen_current_col=$24 ; CH - Horizontal cursor-position (0-39)
    screen_current_row=$25 ; CV - Vertical cursor-position (0-23)

    ;
    ;use Apple 2 monitor ROM function to display 1 char
    ;inputs: A should be set to ASCII char to display
    ;outputs: none
    print_a:
      ora  #$80  ;turn ASCII into Apple 2 screen codes
      cmp #$8A   ;is it a line feed?
      bne @not_line_feed
    ;  jmp print_cr
      pha
      lda #$0
      sta screen_current_col
      pla
    @not_line_feed:

      jmp $fded

    ;use Apple 2 monitor ROM function to move to new line
    ;inputs: none
    ;outputs: none
    print_cr:

      jmp $fd8e

    ;use Apple 2 monitor ROM function to move to clear the screen
    ;inputs: none
    ;outputs: none
    cls:
        jmp $fc58

    ;use Apple 2 monitor ROM function to move to make a 'beep' noise
    ;inputs: none
    ;outputs: none
    beep:
      jmp $fbdd

    print_a_inverse:
      and  #$7F  ;turn off top bits
      jsr $fded

    ;-- LICENSE FOR a2print.s --
    ; The contents of this file are subject to the Mozilla Public License
    ; Version 1.1 (the "License"); you may not use this file except in
    ; compliance with the License. You may obtain a copy of the License at
    ; http://www.mozilla.org/MPL/
    ;
    ; Software distributed under the License is distributed on an "AS IS"
    ; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
    ; License for the specific language governing rights and limitations
    ; under the License.
    ;
    ; The Original Code is ip65.
    ;
    ; The Initial Developer of the Original Code is Jonno Downes,
    ; jonno@jamtronix.com.
    ; Portions created by the Initial Developer are Copyright (C) 2009
    ; Jonno Downes. All Rights Reserved.
    ; -- LICENSE END --