_PROTOTPE( int do_mycall, (message *m_ptr));						/usr/src/kernel/system.h
#define USE_MYCALL									/usr/src/kernel/config.h
#define SYS_MYCALL	1								/usr/src/include/minix/com.h
#define NR_SYS_CALLS	32								/usr/src/include/minix/com.h
_PROTOTYPE( int sys_mycall, (void));							/usr/src/include/minix/syslib.h
map(SYS_MYCALL, do_mycall);								/usr/src/kernel/system.c
PUBLIC int do_mycall(m_ptr) register message *m_ptr { kprintf("."); return (OK); }	/usr/src/kernel/system/do_mycall.c
( nothing special )									/usr/src/kernel/system/Makefile
( nothing special, let Makefile untouched, use "make Makefile to generate a new one" )	/usr/src/lib/syslib/Makefile.in
#include "syslib.h" PUBLIC int sys_mycall(); { message m; m.m1_i1 = 7; \
	return(_taskcall(SYSTASK, SYS_MYCALL, &m));					/usr/src/lib/syslib/sys_mycall.c
make libraries										/usr/src
( add SYS_MYCALL permitions )								/usr/src/kernel/table.c