diff --git a/CHANGES b/CHANGES
index f6fb5e0..bd2b3bb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,9 @@
           number.
         - Added checks for junk text following correct code. This revealed
           some small other issues, now fixed.
+        - Added CIS instructions; as an extension, for the Inline variants
+          you can specify the descriptor addresses etc as arguments to
+          the instruction (much like an implied .word).
 
 25.04.2020: Rhialto
         version 0.5:
diff --git a/assemble.c b/assemble.c
index 7825795..104b15d 100644
--- a/assemble.c
+++ b/assemble.c
@@ -1722,6 +1722,45 @@ static int assemble(
                         }
                         return CHECK_EOL;
 
+                        {   int nwords;
+                            EX_TREE *expr[4];
+                    case OC_CIS2:
+                        /* Either no operands or 2 (mostly) address operand words
+                         * (extension) */
+                            nwords = 2;
+                            goto cis_common;
+                    case OC_CIS3:
+                        /* Either no operands or 3 (mostly) address operand words
+                         * (extension) */
+                            nwords = 3;
+                            goto cis_common;
+                    case OC_CIS4:
+                        /* Either no operands or 4 (mostly) address operand words
+                         * (extension) */
+                            nwords = 4;
+                    cis_common:
+                            if (!EOL(*cp)) {
+                                for (int i = 0; i < nwords; i++) {
+                                    if (i > 0)
+                                        cp = skipdelim(cp);
+                                    EX_TREE *ex = parse_expr(cp, 0);
+                                    cp = ex->cp;
+                                    expr[i] = ex;
+                                }
+                            } else {
+                                expr[0] = NULL;
+                            }
+
+                            store_word(stack->top, tr, 2, op->value);
+
+                            if (expr[0]) {
+                                for (int i = 0; i < nwords; i++) {
+                                    store_value(stack, tr, 2, expr[i]);
+                                }
+                            }
+                        }
+                        return CHECK_EOL;
+
                     default:
                         report(stack->top, "Unimplemented instruction format\n");
                         return 0;
diff --git a/symbols.c b/symbols.c
index 6d573a5..b1d408e 100644
--- a/symbols.c
+++ b/symbols.c
@@ -463,7 +463,73 @@ void add_symbols(
     add_sym("TSTD", I_TSTD, OC_FPPDST, &instruction_section, &system_st);
     add_sym("TSTF", I_TSTF, OC_FPPDST, &instruction_section, &system_st);
 
-    /* FIXME: The CIS instructions are missing! */
+    /* The CIS instructions */
+    add_sym("ADDNI", I_ADDN|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("ADDN",  I_ADDN,         OC_NONE, &instruction_section, &system_st);
+    add_sym("ADDPI", I_ADDP|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("ADDP",  I_ADDP,         OC_NONE, &instruction_section, &system_st);
+    add_sym("ASHNI", I_ASHN|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("ASHN",  I_ASHN,         OC_NONE, &instruction_section, &system_st);
+    add_sym("ASHPI", I_ASHP|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("ASHP",  I_ASHP,         OC_NONE, &instruction_section, &system_st);
+    add_sym("CMPCI", I_CMPC|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("CMPC",  I_CMPC,         OC_NONE, &instruction_section, &system_st);
+    add_sym("CMPNI", I_CMPN|I_CIS_I, OC_CIS2, &instruction_section, &system_st);
+    add_sym("CMPN",  I_CMPN,         OC_NONE, &instruction_section, &system_st);
+    add_sym("CMPPI", I_CMPP|I_CIS_I, OC_CIS2, &instruction_section, &system_st);
+    add_sym("CMPP",  I_CMPP,         OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTLNI",I_CVTLN|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTLN", I_CVTLN,        OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTLPI",I_CVTLP|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTLP", I_CVTPL,        OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTNLI",I_CVTNL|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTNL", I_CVTNL,        OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTPLI",I_CVTPL|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTPL", I_CVTPL,        OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTNPI",I_CVTNP|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTNP", I_CVTNP,        OC_NONE, &instruction_section, &system_st);
+    add_sym("CVTPNI",I_CVTPN|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("CVTPN", I_CVTPN,        OC_NONE, &instruction_section, &system_st);
+    add_sym("DIVPI", I_DIVP|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("DIVP",  I_DIVP,         OC_NONE, &instruction_section, &system_st);
+    add_sym("LOCCI", I_LOCC|I_CIS_I, OC_CIS2, &instruction_section, &system_st);
+    add_sym("LOCC",  I_LOCC,         OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D0",  I_L2Dr+0,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D1",  I_L2Dr+1,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D2",  I_L2Dr+2,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D3",  I_L2Dr+3,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D4",  I_L2Dr+4,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D5",  I_L2Dr+5,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D6",  I_L2Dr+6,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L2D7",  I_L2Dr+7,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D0",  I_L3Dr+0,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D1",  I_L3Dr+1,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D2",  I_L3Dr+2,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D3",  I_L3Dr+3,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D4",  I_L3Dr+4,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D5",  I_L3Dr+5,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D6",  I_L3Dr+6,       OC_NONE, &instruction_section, &system_st);
+    add_sym("L3D7",  I_L3Dr+7,       OC_NONE, &instruction_section, &system_st);
+    add_sym("MATCI", I_MATC|I_CIS_I, OC_CIS2, &instruction_section, &system_st);
+    add_sym("MATC",  I_MATC,         OC_NONE, &instruction_section, &system_st);
+    add_sym("MOVCI", I_MOVC|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("MOVC",  I_MOVC,         OC_NONE, &instruction_section, &system_st);
+    add_sym("MOVRCI",I_MOVRC|I_CIS_I,OC_CIS3, &instruction_section, &system_st);
+    add_sym("MOVRC", I_MOVRC,        OC_NONE, &instruction_section, &system_st);
+    add_sym("MOVTCI",I_MOVTC|I_CIS_I,OC_CIS4, &instruction_section, &system_st);
+    add_sym("MOVTC", I_MOVTC,        OC_NONE, &instruction_section, &system_st);
+    add_sym("MULPI", I_MULP|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("MULP",  I_MULP,         OC_NONE, &instruction_section, &system_st);
+    add_sym("SCANCI",I_SCANC|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("SCANC", I_SCANC,        OC_NONE, &instruction_section, &system_st);
+    add_sym("SKPCI", I_SKPC|I_CIS_I, OC_CIS2, &instruction_section, &system_st);
+    add_sym("SKPC",  I_SKPC,         OC_NONE, &instruction_section, &system_st);
+    add_sym("SPANCI",I_SPANC|I_CIS_I,OC_CIS2, &instruction_section, &system_st);
+    add_sym("SPANC", I_SPANC,        OC_NONE, &instruction_section, &system_st);
+    add_sym("SUBNI", I_SUBN|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("SUBN",  I_SUBN,         OC_NONE, &instruction_section, &system_st);
+    add_sym("SUBPI", I_SUBP|I_CIS_I, OC_CIS3, &instruction_section, &system_st);
+    add_sym("SUBP",  I_SUBP,         OC_NONE, &instruction_section, &system_st);
 
     add_sym(current_section->label, 0, 0, current_section, &section_st);
 }
diff --git a/symbols.h b/symbols.h
index 926fd44..914a2ca 100644
--- a/symbols.h
+++ b/symbols.h
@@ -207,7 +207,36 @@ enum instruction_ops { I_ADC = 0005500,
     I_XFC = 0076700,
     I_XOR = 0074000,
     I_MFPT = 0000007,
-    /* CIS not implemented - maybe later */
+    /* CIS - Commercial Instruction Set */
+    I_CIS_I = 0000100,          /* Inline arguments */
+    I_CIS_P = 0000020,          /* Packed instead of Numeric */
+    I_ADDN =  0076050,
+    I_ADDP =  0076070,
+    I_ASHN =  0076056,
+    I_ASHP =  0076076,
+    I_CMPC =  0076044,
+    I_CMPN =  0076052,
+    I_CMPP =  0076072,
+    I_CVTLN = 0076057,
+    I_CVTLP = 0076077,
+    I_CVTNL = 0076053,
+    I_CVTPL = 0076073,
+    I_CVTNP = 0076055,
+    I_CVTPN = 0076054,
+    I_DIVP =  0076075,
+    I_LOCC =  0076040,
+    I_L2Dr =  0076020,
+    I_L3Dr =  0076060,
+    I_MATC =  0076045,
+    I_MOVC =  0076030,
+    I_MOVRC=  0076031,
+    I_MOVTC=  0076032,
+    I_MULP =  0076074,
+    I_SCANC=  0076042,
+    I_SKPC =  0076041,
+    I_SPANC=  0076043,
+    I_SUBN =  0076051,
+    I_SUBP =  0076071,
     /* FPU */
     I_ABSD = 0170600,
     I_ABSF = 0170600,
@@ -287,6 +316,12 @@ enum operand_codes { OC_MASK = 0xff00,
     /* FPP fp source: immediate or gen */
     OC_FPPDST = OC_1GEN,
     /* FPP general destination */
+    OC_CIS2 = 0x0c00,
+    /* CIS with 2 parameter words */
+    OC_CIS3 = 0x0d00,
+    /* CIS with 3 parameter words */
+    OC_CIS4 = 0x0e00,
+    /* CIS with 4 parameter words */
     OC__LAST = 0xff00
 };
 
diff --git a/tests/RunTests b/tests/RunTests
index 6b99205..d97a13c 100755
--- a/tests/RunTests
+++ b/tests/RunTests
@@ -10,6 +10,7 @@ TESTS="test-asciz \
     test-backpatch \
     test-blkb \
     test-bsl-mac-arg \
+    test-cis \
     test-complex-reloc \
     test-enabl-ama \
     test-enabl-lcm \
diff --git a/tests/test-cis.lst.ok b/tests/test-cis.lst.ok
new file mode 100644
index 0000000..859bec8
--- /dev/null
+++ b/tests/test-cis.lst.ok
@@ -0,0 +1,92 @@
+       1                                ;;;;;
+       2                                ;
+       3                                ; Test assembling the CIS instructions (Commercial Instruction Set).
+       4                                ;
+       5                                
+       6 000000 076050                          ADDN
+       7 000002 076070                          ADDP
+       8 000004 076056                          ASHN
+       9 000006 076076                          ASHP
+      10 000010 076044                          CMPC
+      11 000012 076052                          CMPN
+      12 000014 076072                          CMPP
+      13 000016 076057                          CVTLN
+      14 000020 076073                          CVTLP
+      15 000022 076053                          CVTNL
+      16 000024 076073                          CVTPL
+      17 000026 076055                          CVTNP
+      18 000030 076054                          CVTPN
+      19 000032 076075                          DIVP
+      20 000034 076040                          LOCC
+      21 000036 076020                          L2D0
+      22 000040 076027                          L2D7
+      23 000042 076060                          L3D0
+      24 000044 076067                          L3D7
+      25 000046 076045                          MATC
+      26 000050 076030                          MOVC
+      27 000052 076031                          MOVRC
+      28 000054 076032                          MOVTC
+      29 000056 076074                          MULP
+      30 000060 076042                          SCANC
+      31 000062 076041                          SKPC
+      32 000064 076043                          SPANC
+      33 000066 076051                          SUBN
+      34 000070 076071                          SUBP
+      35                                
+      36 000072 076150  000352' 000356'         ADDNI   s1, s2, d1
+         000100 000362'                 
+      37 000102 076170  000352' 000356'         ADDPI   s1, s2, d1
+         000110 000362'                 
+      38 000112 076156  000352' 000362'         ASHNI   s1, d1, <<'5*256.>!3>   ; rounding digit and shift count
+         000120 032403                  
+      39 000122 076176  000352' 000362'         ASHPI   s1, d1, <<'5*256.>!3>
+         000130 032403                  
+      40 000132 076144  000352' 000356'         CMPCI   s1, s2, 'F              ; fill character
+         000140 000106                  
+      41 000142 076152  000352' 000356'         CMPNI   s1, s2
+      42 000150 076172  000352' 000356'         CMPPI   s1, s2
+      43 000156 076157  000352' 000366'         CVTLNI  s1, l1
+      44 000164 076177  000352' 000366'         CVTLPI  s1, l1
+      45 000172 076153  000352' 000366'         CVTNLI  s1, l1
+      46 000200 076173  000352' 000366'         CVTPLI  s1, l1
+      47 000206 076155  000352' 000362'         CVTNPI  s1, d1
+      48 000214 076154  000352' 000362'         CVTPNI  s1, d1
+      49 000222 076175  000352' 000356'         DIVPI   s1, s2, d1
+         000230 000362'                 
+      50 000232 076140  000352' 000101          LOCCI   s1, 'A
+      51 000240 076145  000352' 000356'         MATCI   s1, s2
+      52 000246 076130  000352' 000362'         MOVCI   s1, d1, 'F              ; fill character
+         000254 000106                  
+      53 000256 076131  000352' 000362'         MOVRCI  s1, d1, 'F              ; fill character
+         000264 000106                  
+      54 000266 076132  000352' 000362'         MOVTCI  s1, d1, 'F, t1
+         000274 000106  000372'         
+      55 000300 076174  000352' 000356'         MULPI   s1, s2, d1
+         000306 000362'                 
+      56 000310 076142  000352' 000356'         SCANCI  s1, s2                  ; src and set descriptors
+      57 000316 076141  000352' 000123          SKPCI   s1, 'S                  ; skip character
+      58 000324 076143  000352' 000356'         SPANCI  s1, s2                  ; src and set descriptors
+      59 000332 076151  000352' 000356'         SUBNI   s1, s2, d1
+         000340 000362'                 
+      60 000342 076171  000352' 000356'         SUBPI   s1, s2, d1
+         000350 000362'                 
+      61                                
+      62 000352 000001  000002          s1:     .word 1, 2      ; string descriptor
+      63 000356 000003  000004          s2:     .word 3, 4      ; string descriptor
+      64 000362 000005  000006          d1:     .word 5, 6      ; string descriptor
+      65 000366 000007  000010          l1:     .word 7, 10     ; long integer
+      66 000372    116     117     120  t1:     .ascii /NOPABC/ ; translation table
+         000375    101     102     103  
+      66                                
+
+
+Symbol table
+
+.       ******R      001 L1      000366R      001 S2      000356R      001 
+D1      000362R      001 S1      000352R      001 T1      000372R      001 
+
+
+Program sections:
+
+. ABS.  000000    000   (RW,I,GBL,ABS,OVR,NOSAV)
+        000400    001   (RW,I,LCL,REL,CON,NOSAV)
diff --git a/tests/test-cis.mac b/tests/test-cis.mac
new file mode 100644
index 0000000..13ada9c
--- /dev/null
+++ b/tests/test-cis.mac
@@ -0,0 +1,66 @@
+;;;;;
+;
+; Test assembling the CIS instructions (Commercial Instruction Set).
+;
+
+        ADDN
+        ADDP
+        ASHN
+        ASHP
+        CMPC
+        CMPN
+        CMPP
+        CVTLN
+        CVTLP
+        CVTNL
+        CVTPL
+        CVTNP
+        CVTPN
+        DIVP
+        LOCC
+        L2D0
+        L2D7
+        L3D0
+        L3D7
+        MATC
+        MOVC
+        MOVRC
+        MOVTC
+        MULP
+        SCANC
+        SKPC
+        SPANC
+        SUBN
+        SUBP
+
+        ADDNI   s1, s2, d1
+        ADDPI   s1, s2, d1
+        ASHNI   s1, d1, <<'5*256.>!3>   ; rounding digit and shift count
+        ASHPI   s1, d1, <<'5*256.>!3>
+        CMPCI   s1, s2, 'F              ; fill character
+        CMPNI   s1, s2
+        CMPPI   s1, s2
+        CVTLNI  s1, l1
+        CVTLPI  s1, l1
+        CVTNLI  s1, l1
+        CVTPLI  s1, l1
+        CVTNPI  s1, d1
+        CVTPNI  s1, d1
+        DIVPI   s1, s2, d1
+        LOCCI   s1, 'A
+        MATCI   s1, s2
+        MOVCI   s1, d1, 'F              ; fill character
+        MOVRCI  s1, d1, 'F              ; fill character
+        MOVTCI  s1, d1, 'F, t1
+        MULPI   s1, s2, d1
+        SCANCI  s1, s2                  ; src and set descriptors
+        SKPCI   s1, 'S                  ; skip character
+        SPANCI  s1, s2                  ; src and set descriptors
+        SUBNI   s1, s2, d1
+        SUBPI   s1, s2, d1
+
+s1:     .word 1, 2      ; string descriptor
+s2:     .word 3, 4      ; string descriptor
+d1:     .word 5, 6      ; string descriptor
+l1:     .word 7, 10     ; long integer
+t1:     .ascii /NOPABC/ ; translation table