CHRIN
| Function | Address | Description |
|---|---|---|
| CHRIN | FFCF | Get a character from the input channel |
This routine gets a byte of data from a channel already set up as the input channel by the CHKIN routine. If 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 Y index register is unchanged and is usually used in a loop to store received characters.
The channel remains open after the call.
Reading from the Keyboard
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 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.
Example:
.readLine LDY #0 ; Prepare Y register to store data
.readLoop JSR CHRIN ; Get next character
STA BUF,Y ; Store in BUF (0x200 89 byte basic input buffer)
INY
CMP #0x0D ; Carriage Return
BNE readLoop ; Loop back for next character
RTS
Example:
This example does no bounds checking so if more than 89 characters are read it will overwrite the Kernal workspace in page 2.