diff --git a/extra/assembly/rdna3/asm.py b/extra/assembly/rdna3/asm.py
index d8f4abe962..01351914e4 100644
--- a/extra/assembly/rdna3/asm.py
+++ b/extra/assembly/rdna3/asm.py
@@ -434,7 +434,8 @@ def disasm(inst: Inst) -> str:
       if op_name == 's_swappc_b64': return f"{op_name} {_fmt_sdst(sdst, 2)}, {_fmt_ssrc(ssrc0, 2)}"
       if op_name in ('s_sendmsg_rtn_b32', 's_sendmsg_rtn_b64'):
         return f"{op_name} {_fmt_sdst(sdst, 2 if 'b64' in op_name else 1)}, sendmsg({MSG_NAMES.get(ssrc0, str(ssrc0))})"
-      return f"{op_name} {_fmt_sdst(sdst, dst_cnt)}, {_fmt_ssrc(ssrc0, src0_cnt)}"
+      ssrc0_str = fmt_src(ssrc0) if src0_cnt == 1 else _fmt_ssrc(ssrc0, src0_cnt)
+      return f"{op_name} {_fmt_sdst(sdst, dst_cnt)}, {ssrc0_str}"
     if cls_name == 'SOP2':
       sdst, ssrc0, ssrc1 = [unwrap(inst._values.get(f, 0)) for f in ('sdst', 'ssrc0', 'ssrc1')]
       return f"{op_name} {_fmt_sdst(sdst, dst_cnt)}, {_fmt_ssrc(ssrc0, src0_cnt)}, {_fmt_ssrc(ssrc1, src1_cnt)}"
@@ -476,7 +477,8 @@ def parse_operand(op: str) -> tuple:
     v = -int(m.group(1), 16) if op.startswith('-') else int(m.group(1), 16)
     return (v, neg, abs_, hi_half)
   if op in SPECIAL_REGS: return (SPECIAL_REGS[op], neg, abs_, hi_half)
-  if m := re.match(r'^([svt](?:tmp)?)\[(\d+):(\d+)\]$', op): return (REG_MAP[m.group(1)][int(m.group(2)):int(m.group(3))+1], neg, abs_, hi_half)
+  if op == 'lit': return (RawImm(255), neg, abs_, hi_half)  # literal marker (actual value comes from literal word)
+  if m := re.match(r'^([svt](?:tmp)?)\[(\d+):(\d+)\]$', op): return (REG_MAP[m.group(1)][int(m.group(2)):int(m.group(3))], neg, abs_, hi_half)
   if m := re.match(r'^([svt](?:tmp)?)(\d+)$', op):
     reg = REG_MAP[m.group(1)][int(m.group(2))]
     reg.hi = hi_half
diff --git a/extra/assembly/rdna3/lib.py b/extra/assembly/rdna3/lib.py
index 103326f3a0..f93149eed0 100644
--- a/extra/assembly/rdna3/lib.py
+++ b/extra/assembly/rdna3/lib.py
@@ -51,7 +51,7 @@ class _RegFactory(Generic[T]):
   @overload
   def __getitem__(self, key: slice) -> Reg: ...
   def __getitem__(self, key: int | slice) -> Reg:
-    return self._cls(key.start, key.stop - key.start) if isinstance(key, slice) else self._cls(key)
+    return self._cls(key.start, key.stop - key.start + 1) if isinstance(key, slice) else self._cls(key)
   def __repr__(self): return f"<{self._name} factory>"
 
 class SGPR(Reg): pass
@@ -118,8 +118,30 @@ class Inst:
 
   def __init__(self, *args, literal: int | None = None, **kwargs):
     self._values, self._literal = dict(self._defaults), literal
-    self._values.update(zip([n for n in self._fields if n != 'encoding'], args))
-    self._values.update(kwargs)
+    # Map positional args to field names
+    field_names = [n for n in self._fields if n != 'encoding']
+    orig_args = dict(zip(field_names, args))
+    orig_args.update(kwargs)
+    self._values.update(orig_args)
+    # Validate register counts for SMEM instructions (before encoding)
+    if self.__class__.__name__ == 'SMEM':
+      op_val = orig_args.get(field_names[0]) if args else orig_args.get('op')
+      if op_val is not None:
+        if hasattr(op_val, 'value'): op_val = op_val.value
+        expected_cnt = {0:1, 1:2, 2:4, 3:8, 4:16, 8:1, 9:2, 10:4, 11:8, 12:16}.get(op_val)
+        sdata_val = orig_args.get('sdata')
+        if expected_cnt is not None and isinstance(sdata_val, Reg) and sdata_val.count != expected_cnt:
+          raise ValueError(f"SMEM op {op_val} expects {expected_cnt} registers, got {sdata_val.count}")
+    # Validate register counts for SOP1 instructions (b32 = 1 reg, b64 = 2 regs)
+    if self.__class__.__name__ == 'SOP1':
+      op_val = orig_args.get(field_names[0]) if args else orig_args.get('op')
+      if op_val is not None and hasattr(op_val, 'name'):
+        expected = 2 if op_val.name.endswith('_B64') else 1
+        sdst_val, ssrc0_val = orig_args.get('sdst'), orig_args.get('ssrc0')
+        if isinstance(sdst_val, Reg) and sdst_val.count != expected:
+          raise ValueError(f"SOP1 {op_val.name} expects {expected} destination register(s), got {sdst_val.count}")
+        if isinstance(ssrc0_val, Reg) and ssrc0_val.count != expected:
+          raise ValueError(f"SOP1 {op_val.name} expects {expected} source register(s), got {ssrc0_val.count}")
     # Type check and encode values
     for name, val in list(self._values.items()):
       if name == 'encoding': continue
@@ -143,6 +165,9 @@ class Inst:
         # Track literal value if needed (encoded as 255)
         if encoded == 255 and self._literal is None and isinstance(val, int) and not isinstance(val, IntEnum):
           self._literal = val
+        elif encoded == 255 and self._literal is None and isinstance(val, float):
+          import struct
+          self._literal = struct.unpack('<I', struct.pack('<f', val))[0]
       # Encode raw register fields for consistent repr
       elif name in RAW_FIELDS:
         if isinstance(val, Reg): self._values[name] = _encode_reg(val)
@@ -209,6 +234,12 @@ class Inst:
     lit = f", literal={hex(self._literal)}" if self._literal is not None else ""
     return f"{self.__class__.__name__}({', '.join(f'{k}={v}' for k, v in items)}{lit})"
 
+  def __eq__(self, other):
+    if not isinstance(other, Inst): return NotImplemented
+    return self.__class__ == other.__class__ and self._values == other._values and self._literal == other._literal
+
+  def __hash__(self): return hash((self.__class__.__name__, tuple(sorted((k, repr(v)) for k, v in self._values.items())), self._literal))
+
   def disasm(self) -> str:
     from extra.assembly.rdna3.asm import disasm
     return disasm(self)
diff --git a/extra/assembly/rdna3/test/test_handwritten.py b/extra/assembly/rdna3/test/test_handwritten.py
index 2a0d17c44b..fc0c16a05f 100644
--- a/extra/assembly/rdna3/test/test_handwritten.py
+++ b/extra/assembly/rdna3/test/test_handwritten.py
@@ -1,7 +1,7 @@
 # do not change these tests. we need to fix bugs to make them pass
 # the Inst constructor should be looking at the types of the fields to correctly set the value
 
-import unittest
+import unittest, struct
 from extra.assembly.rdna3.autogen import *
 from extra.assembly.rdna3.lib import Inst
 from extra.assembly.rdna3.asm import asm
@@ -24,6 +24,33 @@ class TestIntegration(unittest.TestCase):
   def test_load_b128(self):
     self.inst = s_load_b128(s[4:7], s[0:1], NULL, 0)
 
+  def test_load_b128_wrong_size(self):
+    # this should have to be 4 regs on the loaded to
+    with self.assertRaises(Exception):
+      self.inst = s_load_b128(s[4:6], s[0:1], NULL, 0)
+
+  def test_mov_b32(self):
+    self.inst = s_mov_b32(s[80], s[0])
+
+  def test_mov_b64(self):
+    self.inst = s_mov_b64(s[80:81], s[0:1])
+
+  def test_mov_b32_wrong(self):
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b32(s[80:81], s[0:1])
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b32(s[80:81], s[0])
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b32(s[80], s[0:1])
+
+  def test_mov_b64_wrong(self):
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b64(s[80], s[0])
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b64(s[80], s[0:1])
+    with self.assertRaises(Exception):
+      self.inst = s_mov_b64(s[80:81], s[0])
+
   def test_load_b128_no_0(self):
     self.inst = s_load_b128(s[4:7], s[0:1], NULL)
 
@@ -84,5 +111,68 @@ class TestIntegration(unittest.TestCase):
   def test_dual_mul(self):
     self.inst = v_dual_mul_f32(VOPDOp.V_DUAL_MUL_F32, vdstx=v[0], vdsty=v[1], srcx0=v[2], vsrcx1=v[3], srcy0=v[4], vsrcy1=v[5])
 
+  def test_simple_int_to_s(self):
+    self.inst = s_mov_b32(s[0], 3)
+
+  def test_complex_int_to_s(self):
+    self.inst = s_mov_b32(s[0], 0x235646)
+
+  def test_simple_float_to_s(self):
+    self.inst = s_mov_b32(s[0], 1.0)
+
+  def test_complex_float_to_s(self):
+    self.inst = s_mov_b32(s[0], 1337.0)
+    int_inst = s_mov_b32(s[0], struct.unpack("I", struct.pack("f", 1337.0))[0])
+    self.assertEqual(self.inst, int_inst)
+
+class TestRegisterSliceSyntax(unittest.TestCase):
+  """
+  Issue: Register slice syntax should use AMD assembly convention (inclusive end).
+
+  In AMD assembly, s[4:7] means registers s4, s5, s6, s7 (4 registers, inclusive).
+  The DSL should match this convention so that:
+  - s[4:7] gives 4 registers
+  - Disassembler output can be copied directly back into DSL code
+
+  Fix: Change _RegFactory.__getitem__ to use inclusive end:
+    key.stop - key.start + 1  (instead of key.stop - key.start)
+  """
+  def test_register_slice_count(self):
+    # s[4:7] should give 4 registers: s4, s5, s6, s7 (AMD convention, inclusive)
+    reg = s[4:7]
+    self.assertEqual(reg.count, 4, "s[4:7] should give 4 registers (s4, s5, s6, s7)")
+
+  def test_register_slice_roundtrip(self):
+    # Round-trip: DSL -> disasm -> DSL should preserve register count
+    reg = s[4:7]  # 4 registers in AMD convention
+    inst = s_load_b128(reg, s[0:1], NULL, 0)
+    disasm = inst.disasm()
+    # Disasm shows s[4:7] - user should be able to copy this back
+    self.assertIn("s[4:7]", disasm)
+    # And s[4:7] in DSL should give the same 4 registers
+    reg_from_disasm = s[4:7]
+    self.assertEqual(reg_from_disasm.count, 4, "s[4:7] from disasm should give 4 registers")
+
+class TestInstructionEquality(unittest.TestCase):
+  """
+  Issue: No __eq__ method - instruction comparison requires repr() workaround.
+
+  Two identical instructions should compare equal with ==, but currently:
+    inst1 == inst2 returns False
+
+  The test_handwritten.py works around this with:
+    self.assertEqual(repr(self.inst), repr(reasm))
+  """
+  def test_identical_instructions_equal(self):
+    inst1 = v_mov_b32_e32(v[0], v[1])
+    inst2 = v_mov_b32_e32(v[0], v[1])
+    self.assertEqual(inst1, inst2, "identical instructions should be equal")
+
+  def test_different_instructions_not_equal(self):
+    inst1 = v_mov_b32_e32(v[0], v[1])
+    inst2 = v_mov_b32_e32(v[0], v[2])
+    self.assertNotEqual(inst1, inst2, "different instructions should not be equal")
+
+
 if __name__ == "__main__":
   unittest.main()
diff --git a/extra/assembly/rdna3/test/test_integration.py b/extra/assembly/rdna3/test/test_integration.py
index 39f9a272df..0d22640ba4 100644
--- a/extra/assembly/rdna3/test/test_integration.py
+++ b/extra/assembly/rdna3/test/test_integration.py
@@ -189,7 +189,7 @@ class TestAsm(unittest.TestCase):
   def test_asm_register_range(self):
     """Test parsing register ranges."""
     inst = asm('s_load_b128 s[4:7], s[0:1], null')
-    self.assertEqual(inst.to_bytes(), s_load_b128(s[4:8], s[0:2], NULL).to_bytes())
+    self.assertEqual(inst.to_bytes(), s_load_b128(s[4:7], s[0:1], NULL).to_bytes())
 
   def test_asm_matches_llvm(self):
     """Test asm() output matches LLVM assembler."""