Kernal Calls

Official OS calls

The entries below are the official¹ Kernal entry points for the Commodore 64.

1 - Except for CLRLN & CLSR which are from the ROM disassembly but are useful.

Files

CLALL	Close all open files
CLOSE	Close a logical file
LOAD	Load memory from a device
OPEN	Open a logical file
SAVE	Save memory to a device
SETLFS	Setup a logical file
SETNAM	Set file name

Channels

CHKIN	Open channel for input
CHKOUT	Open channel for output
CHRIN	Get a character from the input channel
CHROUT	Output a character
CLRCHN	Clear I/O channels
READST	Read status word

IEEE Serial Bus

ACPTR	Get data from the serial bus
CIOUT	Transmit a byte over the serial bus
LISTEN	Command a device on serial bus to LISTEN
SECOND	Send secondary address for LISTEN
SETTMO	Set IEEE bus card timeout
TALK	Command a device on serial bus to TALK
TKSA	Send secondary address to a device commanded to TALK
UNLSN	Send an UNLISTEN command
UNTLK	Send an UNTALK command

Keyboard

GETIN	Get a character
SCNKEY	Scan the keyboard
STOP	Check if key/stop key is pressed

Memory

IOBASE	Define I/O memory page
MEMBOT	Set bottom of memory
MEMTOP	Set top of memory
RAMTAS	Perform RAM test

Screen

CLRLN	Clear the line X
CLSR	Clear the screen
PLOT	Set cursor location
SCREEN	Return screen format
SETMSG	Control system message output

System

CINT	Initialise screen editor
IOINIT	Initialise I/O Devices
RESTOR	Restore default system & interrup vectors
VECTOR	Manage RAM Vectors

Time

RDTIM	Read system clock
SETTIM	Set system clock
UDTIM	Update system clock

Last modified November 1, 2021: Start adding the 1541/D64 disk format (ebd206c)