So, in v6, it was possible to use the mesg function from the system library with: ed hello.s / hello world using external mesg routine .globl mesg mov sp,r5 jsr r5,mesg; <Hello, World!\n\0>; .even sys exit as hello.sld -s a.out -l a.out Hello, World! This was because v6 included mesg in the library, in v7, it doesn't look like mesg is included, so doing the same thing as above requires that code to write the message out be included and in addition system call names are not predefined, so exit and write have to be looked up in /usr/include/sys.s, resulting in the v7 equivalent file: ed hello2.s / hello world using internal mesg routine         mov     sp,r5         jsr     r5,mesg; <Hello, World!\n\0>; .even         sys     1 mesg:         mov     r0,-(sp)         mov     r5,r0         mov     r5,0f 1:         tstb    (r5)+         bne     1b         sub     r5,r0         com     r0         mov     r0,0f+2         mov     $1,r0         sys     0; 9f .data 9:         sys     4; 0:..; .. .text         inc     r5         bic     $1,r5         mov     (sp)+,r0         rts     r5 as hello2.s a.out Hello, World! My questions are: 1. Is mesg or an equivalent available in v7? 2. If not, what was the v7 way of putting strings out? 3. Why aren't the system call names defined? 4. What was the v7 way of naming system calls? Will