diff --git a/erlang/apps/sim/src/sim_core.erl b/erlang/apps/sim/src/sim_core.erl
index 946a4de..736e243 100644
--- a/erlang/apps/sim/src/sim_core.erl
+++ b/erlang/apps/sim/src/sim_core.erl
@@ -357,6 +357,10 @@ dispatch(Core, Mem, IR, EA) ->
     8#551 -> sim_moves:handle_MOVEI(Core, Mem, IR, EA); % HRRZI = MOVEI
     8#552 -> sim_halfword:handle_HRRZM(Core, Mem, IR, EA);
     8#553 -> sim_halfword:handle_HRRZS(Core, Mem, IR, EA);
+    8#560 -> sim_halfword:handle_HRRO(Core, Mem, IR, EA);
+    8#561 -> sim_halfword:handle_HRROI(Core, Mem, IR, EA);
+    8#562 -> sim_halfword:handle_HRROM(Core, Mem, IR, EA);
+    8#563 -> sim_halfword:handle_HRROS(Core, Mem, IR, EA);
     _ ->
       PC = (Core#core.pc_section bsl 18) bor Core#core.pc_offset,
       {Core, Mem, {error, {?MODULE, {dispatch, PC, IR, EA}}}}
diff --git a/erlang/apps/sim/src/sim_halfword.erl b/erlang/apps/sim/src/sim_halfword.erl
index 0ddf8b4..9d4f5c6 100644
--- a/erlang/apps/sim/src/sim_halfword.erl
+++ b/erlang/apps/sim/src/sim_halfword.erl
@@ -56,6 +56,10 @@
         , handle_HRR/4
         , handle_HRRI/4
         , handle_HRRM/4
+        , handle_HRRO/4
+        , handle_HRROI/4
+        , handle_HRROM/4
+        , handle_HRROS/4
         , handle_HRRS/4
         , handle_HRRZ/4
         , handle_HRRZM/4
@@ -500,6 +504,49 @@ handle_HRRZS(Core, Mem, IR, EA) ->
                           fun(Core1, Mem1) -> ?FUNCTION_NAME(Core1, Mem1, IR, EA) end)
   end.
 
+%% HRRO - Half Word Right to Right, Ones
+
+-spec handle_HRRO(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_HRRO(Core, Mem, IR, EA) ->
+  case sim_core:c(Core, Mem, EA) of
+    {ok, CE} ->
+      AC = IR band 8#17,
+      Word = set_right_ones(get_right(CE)),
+      sim_core:next_pc(sim_core:set_ac(Core, AC, Word), Mem);
+    {error, Reason} ->
+      sim_core:page_fault(Core, Mem, ea_address(EA), read, Reason,
+                          fun(Core1, Mem1) -> ?FUNCTION_NAME(Core1, Mem1, IR, EA) end)
+  end.
+
+-spec handle_HRROI(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_HRROI(Core, Mem, IR, EA) ->
+  AC = IR band 8#17,
+  Word = set_right_ones(EA#ea.offset),
+  sim_core:next_pc(sim_core:set_ac(Core, AC, Word), Mem).
+
+-spec handle_HRROM(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_HRROM(Core, Mem, IR, EA) ->
+  AC = IR band 8#17,
+  CA = sim_core:get_ac(Core, AC),
+  Word = set_right_ones(get_right(CA)),
+  handle_writeback(Core, Mem, EA, Word).
+
+-spec handle_HRROS(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_HRROS(Core, Mem, IR, EA) ->
+  case sim_core:c(Core, Mem, EA) of
+    {ok, CE} ->
+      AC = IR band 8#17,
+      Word = set_right_ones(get_right(CE)),
+      handle_writeback(Core, Mem, AC, EA, Word);
+    {error, Reason} ->
+      sim_core:page_fault(Core, Mem, ea_address(EA), read, Reason,
+                          fun(Core1, Mem1) -> ?FUNCTION_NAME(Core1, Mem1, IR, EA) end)
+  end.
+
 %% Miscellaneous ===============================================================
 
 handle_writeback(Core, Mem, EA, Word) ->
@@ -539,3 +586,5 @@ set_left_ones(Left) -> (Left bsl 18) bor ((1 bsl 18) - 1).
 set_left_zeros(Left) -> Left bsl 18.
 
 set_right(Word, Right) -> (Word band (((1 bsl 18) - 1) bsl 18)) bor Right.
+
+set_right_ones(Right) -> (((1 bsl 18) - 1) bsl 18) bor Right.
diff --git a/erlang/apps/sim/test/sim_halfword_tests.erl b/erlang/apps/sim/test/sim_halfword_tests.erl
index 6b6c57d..9888d41 100644
--- a/erlang/apps/sim/test/sim_halfword_tests.erl
+++ b/erlang/apps/sim/test/sim_halfword_tests.erl
@@ -85,6 +85,10 @@
 -define(OP_HRRZI, 8#551).
 -define(OP_HRRZM, 8#552).
 -define(OP_HRRZS, 8#553).
+-define(OP_HRRO,  8#560).
+-define(OP_HRROI, 8#561).
+-define(OP_HRROM, 8#562).
+-define(OP_HRROS, 8#563).
 
 %% 2.8 Half-Word Data Transmission =============================================
 
@@ -689,6 +693,64 @@ hrrzs_no_ac_test() ->
          , {#ea{section = 1, offset = 0, islocal = false}, ?COMMA2(1, 0)} % AC0 = 1,,0
          ]).
 
+%% HRRO - Half Word Right to Right, Ones
+
+hrro_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 1, 0, 0, 1)}     % 1,,100/ MOVEI 1,1
+    , {1, 8#101, ?INSN(?OP_HRRO, 1, 0, 0, 8#200)}  % 1,,101/ HRRO 1,200
+    , {1, 8#102, ?INSN_INVALID}                    % 1,,102/ <invalid>
+    , {1, 8#200, ?COMMA2(0, 2)}                    % 1,,200/ 0,,2
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 1, islocal = false}, ?COMMA2(-1, 2)} % AC1 = -1,,2
+         ]).
+
+hrroi_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 1, 0, 0, 1)}     % 1,,100/ MOVEI 1,1
+    , {1, 8#101, ?INSN(?OP_HRROI, 1, 0, 0, 2)}     % 1,,101/ HRROI 1,2
+    , {1, 8#102, ?INSN_INVALID}                    % 1,,102/ <invalid>
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 1, islocal = false}, ?COMMA2(-1, 2)} % AC1 = -1,,2
+         ]).
+
+hrrom_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 1, 0, 0, 2)}     % 1,,100/ MOVEI 1,2
+    , {1, 8#101, ?INSN(?OP_HRROM, 1, 0, 0, 8#200)} % 1,,101/ HRROM 1,200
+    , {1, 8#102, ?INSN_INVALID}                    % 1,,102/ <invalid>
+    , {1, 8#200, ?COMMA2(0, 1)}                    % 1,,200/ 0,,1
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 8#200, islocal = false}, ?COMMA2(-1, 2)} % C(1,,200) = -1,,2
+         ]).
+
+hrros_ac_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 1, 0, 0, 1)}     % 1,,100/ MOVEI 1,1
+    , {1, 8#101, ?INSN(?OP_HRROS, 1, 0, 0, 8#200)} % 1,,101/ HRROS 1,200
+    , {1, 8#102, ?INSN_INVALID}                    % 1,,102/ <invalid>
+    , {1, 8#200, ?COMMA2(0, 2)}                    % 1,,200/ 0,,2
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 8#200, islocal = false}, ?COMMA2(-1, 2)} % C(1,,200) = -1,,2
+         , {#ea{section = 1, offset = 1, islocal = false}, ?COMMA2(-1, 2)} % AC1 = -1,,2
+         ]).
+
+hrros_no_ac_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 0, 0, 0, 1)}     % 1,,100/ MOVEI 0,1
+    , {1, 8#101, ?INSN(?OP_HRROS, 1, 0, 0, 8#200)} % 1,,101/ HRROS 1,200
+    , {1, 8#102, ?INSN_INVALID}                    % 1,,102/ <invalid>
+    , {1, 8#200, ?COMMA2(0, 2)}                    % 1,,200/ 0,,2
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 8#200, islocal = false}, ?COMMA2(-1, 2)} % C(1,,200) = -1,,2
+         , {#ea{section = 1, offset = 0, islocal = false}, ?COMMA2(0, 1)} % AC0 = 0,,1
+         ]).
+
 %% Common code to run short sequences ==========================================
 
 expect(Prog, ACs, ExpectedPC, ExpectedFlags, ExpectedEs) ->