From 621201978fa3d37ee6183ca27759003911ae5149 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Victor?= <bjorn@victor.se>
Date: Thu, 20 Apr 2023 20:06:24 +0200
Subject: [PATCH] Patch the value of IMPUS3 when IP is read from the IMP

---
 src/system/{imp.368 => imp.369} | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 rename src/system/{imp.368 => imp.369} (99%)

diff --git a/src/system/imp.368 b/src/system/imp.369
similarity index 99%
rename from src/system/imp.368
rename to src/system/imp.369
index 16a400e8..19da6647 100644
--- a/src/system/imp.368
+++ b/src/system/imp.369
@@ -629,6 +629,19 @@ IMPIN:	LDB T,[241000,,IMPILB+0]	;get network byte (ip[0])
 	MOVE T,NIFIPA		; make network part of address
 	AND T,NIFIPM
 	MOVEM T,NIFIPN		; save it
+	;; Backwards compatibility for RESOLV"OWNHST (used by e.g. COMSAT):
+	;; patch the IMPUS3 symbol
+	PUSH P,A		;Save the ACs clobbered by symlk
+	PUSH P,B
+	PUSH P,C
+	MOVE B,[SQUOZE 0,IMPUS3]
+	PUSHJ P,SYMLK
+	 BUG HALT,[IMPUS3 symbol not found]
+	MOVE A,NIFIPA
+	MOVEM A,(C)		;Zap the symbol value
+	POP P,C
+	POP P,B
+	POP P,A
 	JRST IMPIRT		;One more NOP from IMP
 
 ;;; IMP->Host Type 5 - RFNM (Ready For Next Message)