diff --git a/erlang/apps/sim/src/sim_boolean.erl b/erlang/apps/sim/src/sim_boolean.erl
index dd487c3..b77c8cc 100644
--- a/erlang/apps/sim/src/sim_boolean.erl
+++ b/erlang/apps/sim/src/sim_boolean.erl
@@ -32,6 +32,7 @@
         , handle_ANDCAM/4
         , handle_ANDI/4
         , handle_ANDM/4
+        , handle_SETMB/4
         , handle_SETMI/4
         , handle_SETMM/4
         , handle_SETZ/4
@@ -219,6 +220,19 @@ handle_SETMM(Core, Mem, IR, EA) ->
                           fun(Core1, Mem1) -> handle_SETMM(Core1, Mem1, IR, EA) end)
   end.
 
+-spec handle_SETMB(#core{}, sim_mem:mem(), IR :: word(), #ea{})
+      -> {#core{}, sim_mem:mem(), {ok, integer()} | {error, {module(), term()}}}.
+handle_SETMB(Core, Mem, IR, EA) ->
+  %% Like MOVES, but writes also to AC 0.
+  case sim_core:c(Core, Mem, EA) of
+    {ok, CE} ->
+      AC = IR band 8#17,
+      handle_ANDB(Core, Mem, AC, EA, CE);
+    {error, Reason} ->
+      sim_core:page_fault(Core, Mem, ea_address(EA), read, Reason,
+                          fun(Core1, Mem1) -> handle_SETMB(Core1, Mem1, IR, EA) end)
+  end.
+
 %% Miscellaneous ===============================================================
 
 ea_address(#ea{section = Section, offset = Offset}) ->
diff --git a/erlang/apps/sim/src/sim_core.erl b/erlang/apps/sim/src/sim_core.erl
index ea1f9fd..cdecb64 100644
--- a/erlang/apps/sim/src/sim_core.erl
+++ b/erlang/apps/sim/src/sim_core.erl
@@ -268,6 +268,7 @@ dispatch(Core, Mem, IR, EA) ->
     8#414 -> sim_moves:handle_MOVE(Core, Mem, IR, EA); % SETM = MOVE
     8#415 -> sim_boolean:handle_SETMI(Core, Mem, IR, EA); % SETMI = MOVEI in section 0, XMOVEI elsewhere
     8#416 -> sim_boolean:handle_SETMM(Core, Mem, IR, EA);
+    8#417 -> sim_boolean:handle_SETMB(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/test/sim_boolean_tests.erl b/erlang/apps/sim/test/sim_boolean_tests.erl
index d14cff2..1909979 100644
--- a/erlang/apps/sim/test/sim_boolean_tests.erl
+++ b/erlang/apps/sim/test/sim_boolean_tests.erl
@@ -59,6 +59,7 @@
 -define(OP_SETMI, 8#415).
 -define(OP_XMOVEI, ?OP_SETMI).
 -define(OP_SETMM, 8#416).
+-define(OP_SETMB, 8#417).
 
 %% 2.4 Boolean Functions =======================================================
 
@@ -271,6 +272,18 @@ setmm_test() ->
          , {#ea{section = 1, offset = 1, islocal = false}, 3}
          ]).
 
+setmb_test() ->
+  Prog =
+    [ {1, 8#100, ?INSN(?OP_MOVEI, 0, 0, 0, 8#27)}   % 1,,100/ MOVEI 0,27
+    , {1, 8#101, ?INSN(?OP_SETMB, 0, 0, 0, 8#150)}  % 1,,101/ SETMB 0,150
+    , {1, 8#102, ?INSN_INVALID}                     % 1,,102/ <invalid>
+    , {1, 8#150, 8#42}                              % 1,,150/ 0,,42
+    ],
+  expect(Prog, [], {1, 8#102}, ?DEFAULT_FLAGS,
+         [ {#ea{section = 1, offset = 8#150, islocal = false}, 8#42} % C(1,,150) = 42
+         , {#ea{section = 1, offset = 0, islocal = false}, 8#42} % AC0 = 42
+         ]).
+
 %% Common code to run short sequences ==========================================
 
 expect(Prog, ACs, ExpectedPC, ExpectedFlags, ExpectedEs) ->