Function Name: CHRIN

Purpose: Get a character from the input channel
Call address: $FFCF (hex) 65487 (decimal)
Communication registers:A
Preparatory routines: (OPEN, CHKIN)
Error returns: 0 (See READST)
Stack requirements: 7+
Registers affected: A, X

Description: This routine gets a byte of data from a channel already set up as the input channel by the KERNAL routine CHKIN. If the CHKIN has NOT been used to define another input channel, then all your data is expected from the keyboard. The data byte is returned in the accumulator. The channel remains open after the call.

Input from the keyboard is handled in a special way. First, the cursor is turned on, and blinks until a carriage return is typed on the keyboard. All characters on the line (up to 88 characters) are stored in the BASIC input buffer. These characters can be retrieved one at a time by calling this routine once for each character. When the carriage return is retrieved, the entire line has been processed. The next time this routine is called, the whole process begins again, i.e., by flashing the cursor.

How to Use:

FROM THE KEYBOARD

1. Retrieve a byte of data by calling this routine.
2. Store the data byte.
3. Check if it is the last data byte (is it a CR?)
4. If not, go to step 1.

EXAMPLE:

      LDY $#00      ;PREPARE THE Y REGISTER TO STORE THE DATA
  RD  JSR CHRIN
      STA DATA,Y    ;STORE THE YTH DATA BYTE IN THE YTH
                    ;LOCATION IN THE DATA AREA.
      INY
      CMP #CR       ;IS IT A CARRIAGE RETURN?
      BNE RD        ;NO, GET ANOTHER DATA BYTE

EXAMPLE:

   JSR CHRIN
   STA DATA

FROM OTHER DEVICES

1. Use the KERNAL OPEN and CHKIN routines.
2. Call this routine (using a JSR instruction).
3. Store the data.

EXAMPLE:

   JSR CHRIN
   STA DATA