TITLE CAFDTR Cafard DTR control
	SUBTTL Written by Mark Crispin/MRC

; Copyright (C) 1985, 1987 Mark Crispin.  All rights reserved.

	SEARCH MACSYM,MONSYM	; system definitions
	SALL			; suppress macro expansions
	.DIRECTIVE FLBLST	; sane listings for ASCIZ, etc.

;;; These symbols are defined by DEC in Edits 7435/7436 to TOPS-20.
;;;Some systems (notably Stanford and older PANDA monitors) used
;;;400003 and 400004 respectively.  These should be migrated to the
;;;DEC values...
IFNDEF .MOHUP,.MOHUP==:62	; lower DTR
IFNDEF .MOUHU,.MOUHU==:63	; raise DTR

A=1				; JSYS, temporary AC's
B=2

	.PSECT CODE

; $DTRON - Assert DTR
; Accepts:
;	A/ designator of line to assert DTR on
;	CALL $DTRON
; Returns +1: Always

$DTRON::SAVEAC <A,B>
	MOVX B,.MOUHU		; turn DTR on
	MTOPR%
	 ERJMP .+1
	RET

; $DTROF - Drop DTR
; Accepts:
;	A/ designator of line to drop DTR on
;	CALL $DTROF
; Returns +1: Always

$DTROF::SAVEAC <A,B>
	MOVX B,.MOHUP		; turn DTR off
	MTOPR%
	 ERJMP .+1
	RET

	END