diff --git a/apps/zasm/tests/geninstrs.py b/apps/zasm/tests/geninstrs.py
new file mode 100755
index 0000000..5a0d9d7
--- /dev/null
+++ b/apps/zasm/tests/geninstrs.py
@@ -0,0 +1,152 @@
+#!/usr/bin/python
+# Generate almost all possible combination for instructions from instruction
+# tables
+
+argspecTbl = {
+    'A': "A",
+    'B': "B",
+    'C': "C",
+    'D': "D",
+    'E': "E",
+    'H': "H",
+    'L': "L",
+    'h': "HL",
+    'l': "(HL)",
+    'd': "DE",
+    'e': "(DE)",
+    'b': "BC",
+    'c': "(BC)",
+    'a': "AF",
+    'f': "AF'",
+    'x': "(IX)",
+    'y': "(IY)",
+    's': "SP",
+    'p': "(SP)",
+    'Z': "Z",
+    'z': "NZ",
+    '=': "NC",
+    '+': "P",
+    '-': "M",
+    '1': "PO",
+    '2': "PE",
+}
+
+argGrpTbl = {
+    chr(0x01): "bdha",
+    chr(0x02): "ZzC=",
+    chr(0x03): "bdhs",
+    chr(0x0a): "ZzC=+-12",
+    chr(0x0b): "BCDEHLA",
+}
+
+instrTBlPrimary = [
+    ("ADC", 'A', 'l', 0, 0x8e),
+    ("ADC", 'A', 0xb, 0, 0b10001000),
+    ("ADC", 'A', 'n', 0, 0xce	),
+    ("ADD", 'A', 'l', 0, 0x86	),
+    ("ADD", 'A', 0xb, 0, 0b10000000),
+    ("ADD", 'A', 'n', 0, 0xc6 ),
+    ("ADD", 'h', 0x3, 4, 0b00001001 ),
+    ("AND", 'l', 0,   0, 0xa6	),
+    ("AND", 0xb, 0,   0, 0b10100000),
+    ("AND", 'n', 0,   0, 0xe6	),
+    ("CALL",   0xa, 'N', 3, 0b11000100),
+    ("CALL",   'N', 0,   0, 0xcd	),
+    ("CCF", 0,   0,   0, 0x3f	),
+    ("CP", 'l', 0,   0, 0xbe	),
+    ("CP", 0xb, 0,   0, 0b10111000),
+    ("CP", 'n', 0,   0, 0xfe	),
+    ("CPL", 0,   0,   0, 0x2f	),
+    ("DAA", 0,   0,   0, 0x27	),
+    ("DI", 0,   0,   0, 0xf3	),
+    ("DEC", 'l', 0,   0, 0x35	),
+    ("DEC", 0xb, 0,   3, 0b00000101),
+    ("DEC", 0x3, 0,   4, 0b00001011),
+    ("DJNZ",   'n', 0,0x80, 0x10	),
+    ("EI", 0,   0,   0, 0xfb	),
+    ("EX", 'p', 'h', 0, 0xe3	),
+    ("EX", 'a', 'f', 0, 0x08	),
+    ("EX", 'd', 'h', 0, 0xeb	),
+    ("EXX", 0,   0,   0, 0xd9	),
+    ("HALT",   0,   0,   0, 0x76	),
+    ("IN", 'A', 'm', 0, 0xdb	),
+    ("INC", 'l', 0,   0, 0x34	),
+    ("INC", 0xb, 0,   3, 0b00000100),
+    ("INC", 0x3, 0,   4, 0b00000011),
+    ("JP", 'l', 0,   0, 0xe9	),
+    ("JP", 'N', 0,   0, 0xc3	),
+    ("JR", 'n', 0,0x80, 0x18	),
+    ("JR",'C','n',0x80, 0x38	),
+    ("JR",'=','n',0x80, 0x30	),
+    ("JR",'Z','n',0x80, 0x28	),
+    ("JR",'z','n',0x80, 0x20	),
+    ("LD", 'c', 'A', 0, 0x02	),
+    ("LD", 'e', 'A', 0, 0x12	),
+    ("LD", 'A', 'c', 0, 0x0a	),
+    ("LD", 'A', 'e', 0, 0x0a	),
+    ("LD", 's', 'h', 0, 0x0a	),
+    ("LD", 'l', 0xb, 0, 0b01110000),
+    ("LD", 0xb, 'l', 3, 0b01000110),
+    ("LD", 'l', 'n', 0, 0x36	),
+    ("LD", 0xb, 'n', 3, 0b00000110),
+    ("LD", 0x3, 'N', 4, 0b00000001),
+    ("LD", 'M', 'A', 0, 0x32	),
+    ("LD", 'A', 'M', 0, 0x3a	),
+    ("LD", 'M', 'h', 0, 0x22	),
+    ("LD", 'h', 'M', 0, 0x2a	),
+    ("NOP", 0,   0,   0, 0x00	),
+    ("OR", 'l', 0,   0, 0xb6	),
+    ("OR", 0xb, 0,   0, 0b10110000),
+    ("OUT", 'm', 'A', 0, 0xd3	),
+    ("POP", 0x1, 0,   4, 0b11000001),
+    ("PUSH",   0x1, 0,   4, 0b11000101),
+    ("RET", 0xa, 0,   3, 0b11000000),
+    ("RET", 0,   0,   0, 0xc9	),
+    ("RLA", 0,   0,   0, 0x17	),
+    ("RLCA",   0,   0,   0, 0x07	),
+    ("RRA", 0,   0,   0, 0x1f	),
+    ("RRCA",   0,   0,   0, 0x0f	),
+    ("SBC", 'A', 'l', 0, 0x9e	),
+    ("SBC", 'A', 0xb, 0, 0b10011000),
+    ("SCF", 0,   0,   0, 0x37	),
+    ("SUB", 'A', 'l', 0, 0x96	),
+    ("SUB", 'A', 0xb, 0, 0b10010000),
+    ("SUB", 'n', 0,   0, 0xd6 ),
+    ("XOR", 'l', 0,   0, 0xae	),
+    ("XOR", 0xb, 0,   0, 0b10101000),
+]
+
+def genargs(argspec):
+    if not argspec:
+        return ''
+    if not isinstance(argspec, str):
+        argspec = chr(argspec)
+    if argspec in 'nmNM':
+        bits = 16 if argspec in 'NM' else 8
+        nbs = [str(1 << i) for i in range(bits)]
+        if argspec in 'mM':
+            nbs = [f"({n})" for n in nbs]
+        return nbs
+    if argspec in argspecTbl:
+        return [argspecTbl[argspec]]
+    grp = argGrpTbl[argspec]
+    return [argspecTbl[a] for a in grp]
+
+
+def main():
+    for n, a1, a2, f, op in instrTBlPrimary:
+        args1 = genargs(a1)
+        if args1:
+            for arg1 in args1:
+                args2 = genargs(a2)
+                if args2:
+                    for arg2 in args2:
+                        print(f"{n} {arg1}, {arg2}")
+                else:
+                    print(f"{n} {arg1}")
+        else:
+            print(n)
+    pass
+
+if __name__ == '__main__':
+    main()
diff --git a/apps/zasm/tests/runtests.sh b/apps/zasm/tests/runtests.sh
new file mode 100755
index 0000000..9eec5b1
--- /dev/null
+++ b/apps/zasm/tests/runtests.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -e
+
+TMPFILE=$(mktemp)
+SCAS=scas
+ZASM=../emul/zasm
+
+./geninstrs.py | \
+while read line; do
+    echo $line | tee "${TMPFILE}"
+    EXPECTED=$($SCAS -o - "${TMPFILE}" | xxd)
+    ACTUAL=$(echo $line | $ZASM | xxd)
+    if [ "$ACTUAL" == "$EXPECTED" ]; then
+        echo ok
+    else
+        echo actual
+        echo $ACTUAL
+        echo expected
+        echo $EXPECTED
+        exit 1
+    fi
+done
diff --git a/apps/zasm/zasm.asm b/apps/zasm/zasm.asm
index b5e3f11..8dfe2be 100644
--- a/apps/zasm/zasm.asm
+++ b/apps/zasm/zasm.asm
@@ -223,7 +223,7 @@ toWord:
 readArg:
 	push	de
 	ld	de, tmpBuf
-	ld	a, 6
+	ld	a, 8
 	call	readWord
 	push	hl
 	ld	hl, tmpBuf
@@ -363,6 +363,7 @@ findInGroup:
 	jr	z, .specialGroupCC
 	cp	0xb
 	jr	z, .specialGroupABCDEHL
+	jr	nc, .notfound	; > 0xb? not a group
 	pop	af
 	; regular group
 	push	de
@@ -660,7 +661,8 @@ argspecTbl:
 ; we also need argspecs for the condition flags
 	.db	'Z', "Z", 0, 0, 0
 	.db	'z', "NZ",   0, 0
-	.db	'^', "C", 0, 0, 0
+	; C is in conflict with the C register. The situation is ambiguous, but
+	; doesn't cause actual problems.
 	.db	'=', "NC",   0, 0
 	.db	'+', "P", 0, 0, 0
 	.db	'-', "M", 0, 0, 0
@@ -682,11 +684,11 @@ argspecTbl:
 ; The table below is in order, starting with group 0x01
 argGrpTbl:
 	.db	"bdha"		; 0x01
-	.db	"Zz^="		; 0x02
+	.db	"ZzC="		; 0x02
 	.db	"bdhs"		; 0x03
 
 argGrpCC:
-	.db	"Zz^=+-12"	; 0xa
+	.db	"zZ=C12+-"	; 0xa
 argGrpABCDEHL:
 	.db	"BCDEHL_A"	; 0xb
 
@@ -705,15 +707,15 @@ argGrpABCDEHL:
 ; decreased by 2 (djnz, jr).
 
 instrTBlPrimary:
-	.db "ADC", 0, 'A', 'h', 0, 0x8e		; ADC A, HL
+	.db "ADC", 0, 'A', 'l', 0, 0x8e		; ADC A, (HL)
 	.db "ADC", 0, 'A', 0xb, 0, 0b10001000	; ADC A, r
 	.db "ADC", 0, 'A', 'n', 0, 0xce		; ADC A, n
-	.db "ADD", 0, 'A', 'h', 0, 0x86		; ADD A, HL
+	.db "ADD", 0, 'A', 'l', 0, 0x86		; ADD A, (HL)
 	.db "ADD", 0, 'A', 0xb, 0, 0b10000000	; ADD A, r
 	.db "ADD", 0, 'A', 'n', 0, 0xc6 	; ADD A, n
 	.db "ADD", 0, 'h', 0x3, 4, 0b00001001 	; ADD HL, ss
 	.db "AND", 0, 'l', 0,   0, 0xa6		; AND (HL)
-	.db "AND", 0, 0xa, 0,   0, 0b10100000	; AND r
+	.db "AND", 0, 0xb, 0,   0, 0b10100000	; AND r
 	.db "AND", 0, 'n', 0,   0, 0xe6		; AND n
 	.db "CALL",   0xa, 'N', 3, 0b11000100	; CALL cc, NN
 	.db "CALL",   'N', 0,   0, 0xcd		; CALL NN
@@ -741,15 +743,15 @@ instrTBlPrimary:
 	.db "JP",0,0, 'l', 0,   0, 0xe9		; JP (HL)
 	.db "JP",0,0, 'N', 0,   0, 0xc3		; JP NN
 	.db "JR",0,0, 'n', 0,0x80, 0x18		; JR e
-	.db "JR",0,0,'^','n',0x80, 0x38		; JR C, e
+	.db "JR",0,0,'C','n',0x80, 0x38		; JR C, e
 	.db "JR",0,0,'=','n',0x80, 0x30		; JR NC, e
 	.db "JR",0,0,'Z','n',0x80, 0x28		; JR Z, e
 	.db "JR",0,0,'z','n',0x80, 0x20		; JR NZ, e
 	.db "LD",0,0, 'c', 'A', 0, 0x02		; LD (BC), A
 	.db "LD",0,0, 'e', 'A', 0, 0x12		; LD (DE), A
 	.db "LD",0,0, 'A', 'c', 0, 0x0a		; LD A, (BC)
-	.db "LD",0,0, 'A', 'e', 0, 0x0a		; LD A, (DE)
-	.db "LD",0,0, 's', 'h', 0, 0x0a		; LD SP, HL
+	.db "LD",0,0, 'A', 'e', 0, 0x1a		; LD A, (DE)
+	.db "LD",0,0, 's', 'h', 0, 0xf9		; LD SP, HL
 	.db "LD",0,0, 'l', 0xb, 0, 0b01110000	; LD (HL), r
 	.db "LD",0,0, 0xb, 'l', 3, 0b01000110	; LD r, (HL)
 	.db "LD",0,0, 'l', 'n', 0, 0x36		; LD (HL), n
@@ -765,16 +767,16 @@ instrTBlPrimary:
 	.db "OUT", 0, 'm', 'A', 0, 0xd3		; OUT (n), A
 	.db "POP", 0, 0x1, 0,   4, 0b11000001	; POP qq
 	.db "PUSH",   0x1, 0,   4, 0b11000101	; PUSH qq
-	.db "RET", 0, 0xa, 0,   3, 0b11000000	; RET cc
 	.db "RET", 0, 0,   0,   0, 0xc9		; RET
+	.db "RET", 0, 0xa, 0,   3, 0b11000000	; RET cc
 	.db "RLA", 0, 0,   0,   0, 0x17		; RLA
 	.db "RLCA",   0,   0,   0, 0x07		; RLCA
 	.db "RRA", 0, 0,   0,   0, 0x1f		; RRA
 	.db "RRCA",   0,   0,   0, 0x0f		; RRCA
-	.db "SBC", 0, 'A', 'h', 0, 0x9e		; SBC A, HL
+	.db "SBC", 0, 'A', 'l', 0, 0x9e		; SBC A, (HL)
 	.db "SBC", 0, 'A', 0xb, 0, 0b10011000	; SBC A, r
 	.db "SCF", 0, 0,   0,   0, 0x37		; SCF
-	.db "SUB", 0, 'A', 'h', 0, 0x96		; SUB A, HL
+	.db "SUB", 0, 'A', 'l', 0, 0x96		; SUB A, (HL)
 	.db "SUB", 0, 'A', 0xb, 0, 0b10010000	; SUB A, r
 	.db "SUB", 0, 'n', 0,   0, 0xd6 	; SUB n
 	.db "XOR", 0, 'l', 0,   0, 0xae		; XOR (HL)