Temp

pushl $42 #l ength
lea output, %eax
pushl %eax # string address
pushl $1 # file descriptor number
mov $4,%eax # system call number
push %eax
int $0x80 # make the system call

You can see mach/i386/syscall_sw.h for the different software interrupts available, and sys/syscall.h for the different system call numbers.