diff --git a/src/syseng/11sim.426 b/src/syseng/11sim.427
old mode 100755
new mode 100644
similarity index 99%
rename from src/syseng/11sim.426
rename to src/syseng/11sim.427
index ab13427c..b8f3bb9e
--- a/src/syseng/11sim.426
+++ b/src/syseng/11sim.427
@@ -10031,7 +10031,7 @@ DRB2T:	DRB00
 	ASCIZ/BICB/
 	ASCIZ/BISB/
 	ASCIZ/SUB/
-	DLB1
+	DRB17
 
 ;INSNS STARTING WITH 0000.
 DRB00:	JUMPL	T2,DRB1	;1-OPER. WORD INSN.
@@ -10056,6 +10056,84 @@ DRB00T:	ASCIZ/BR/
 	ASCIZ/BGT/
 	ASCIZ/BLE/
 
+; INSTRUCTIONS OF FORM 17XXXX.
+DRB17:	LSHC	T1,4
+	CAIGE	T1,362
+	 JRST	DRB170
+	SKIPL	T6,DRB17T-362(T1)
+	 JRST	DRB17A
+	LDB	T3,[420200,,T2]
+	SAVE	T3
+	LSHC	T1,2
+	6TYPE	T6
+	TTOI	" 
+	CALL	DPADDR
+	MOVE	T5,%D
+	MOVEM	T5,%S
+	TTOI	",
+	REST	T5
+	JRST	DPAREG
+DRB17A:	MOVNS	T6
+	6TYPE	T6
+	TTOI	" 
+	LDB	T5,[420200,,T2]
+	CALL	DPAREG
+	MOVE	T5,%D
+	MOVEM	T5,%S
+	TTOI	",
+	LSHC	T1,2
+	JRST	DPADDR
+
+DRB17T:	SIXBIT/MULF/
+	SIXBIT/MODF/
+	SIXBIT/ADDF/
+	SIXBIT/LDF/
+	SIXBIT/SUBF/
+	SIXBIT/CMPF/
+	-SIXBIT/STF/	;NEGATED MEANS MEMORY OPERAND LAST
+	SIXBIT/DIVF/
+	-SIXBIT/STEXP/
+	-SIXBIT/STCFI/
+	-SIXBIT/STCFF/
+	SIXBIT/LDEXP/
+	SIXBIT/LDCIF/
+	SIXBIT/LDCFF/
+
+DRB170:	LSHC	T1,2
+	CAIGE	T1,1701
+	 JRST	DR1700
+	6TYPE	DR170T-1701(T1)
+	TTOI	" 
+	JRST	DPADDR
+
+DR170T:	SIXBIT/LDFPS/
+	SIXBIT/STFPS/
+	SIXBIT/STST/
+	SIXBIT/CLRF/
+	SIXBIT/TSTF/
+	SIXBIT/ABSF/
+	SIXBIT/NEGF/
+
+DR1700:	LSHC T1,6
+	CAIL T1,170013
+	 JRST DLB1
+	SKIPN D1700T-170000(T1)
+	 JRST DLB1
+	6TYPE D1700T-170000(T1)
+	RETURN
+
+D1700T:	SIXBIT/CFCC/
+	SIXBIT/SETF/
+	SIXBIT/SETI/
+	0
+	0
+	0
+	0
+	0
+	0
+	SIXBIT/SETD/
+	SIXBIT/SETL/
+
 ; INSTRUCTIONS OF FORM 10XXXX.
 DRB10:	JUMPL	T2,DRB1B
 	LSHC	T1,4