Lab4 - Data Input Form

Our group chose option 2 for Lab 4 part 1. 

1. what you need to know to solve this problem.

1) Text Area

- The emulator has a text area for data entry.
- The checkbox labeled "Text Screen" can be used to hide the character display to free up more space - for editing code.
- The text box can display an 80x25 characters at $f000-$7cff, with one byte per pixel. 
- One line has consisted from 00 to 4f. 
- Printable ASCII characters will be displayed. 
- If the high-order bit is set, the character will be shown in  reverse video .

2) Routines

These routines are defined in ROM.
- SCINIT $ff81 - Initialize and clear the character display
- CHRIN $ffcf - Input one character from keyboard (returns A)
- CHROUT $ffdw - Outputs one character (A) to the screen at the current cursor position.  
                              Screen will wrap/scroll appropriately. Printable characters and cursor code
                              ($80/$81/$82/$83 for up/right/left/down) as well as RETURN ($0d) are accepted.  
                             Printable ASCII codes with the high bit set will be printed in reverse video.
- SCREEN $ffed - Returns the character screen size in the X and Y registers.
- PLOT $fff0 - gets (CARRY=1) or sets (CARRY=0) the cursor position

To use the ROM routines, these define directives may be pasted into your code:

define  SCINIT  $ff81 ; initialize/clear screen
define  CHRIN  $ffcf ; input character from keyboard
define  CHROUT  $ffd2 ; output character to screen
define  SCREEN  $ffed ; get screen size
define  PLOT  $fff0 ; get/set cursor coordinates

You can then access the routines by name using the JSR instruction:

jsr CHROUT