To assemble "UPDN", at the 'OS9' prompt enter:
ASM UPDN #12K

To assemble "UPDN" and generate an executable module in the "CMDS" directory,
at the 'OS9' prompt enter:
ASM UPDN O #12K

To assemble "UPDN" and generate a listing on the screen, at the 'OS9' prompt enter:
ASM UPDN L #12K