diff --git a/kvmd/apps/kvmd/api/switch.py b/kvmd/apps/kvmd/api/switch.py
index bf91b83e..d89f1b84 100644
--- a/kvmd/apps/kvmd/api/switch.py
+++ b/kvmd/apps/kvmd/api/switch.py
@@ -79,6 +79,7 @@ class SwitchApi:
             param: validator(req.query.get(param))
             for (param, validator) in [
                 ("edid_id", (lambda arg: valid_switch_edid_id(arg, allow_default=True))),
+                ("dummy",   valid_bool),
                 ("name",    valid_switch_port_name),
                 ("atx_click_power_delay",      valid_switch_atx_click_delay),
                 ("atx_click_power_long_delay", valid_switch_atx_click_delay),
diff --git a/kvmd/apps/kvmd/switch/__init__.py b/kvmd/apps/kvmd/switch/__init__.py
index f0cc98f2..6f2337a4 100644
--- a/kvmd/apps/kvmd/switch/__init__.py
+++ b/kvmd/apps/kvmd/switch/__init__.py
@@ -32,6 +32,7 @@ from .lib import Inotify
 
 from .types import Edid
 from .types import Edids
+from .types import Dummies
 from .types import Color
 from .types import Colors
 from .types import PortNames
@@ -68,6 +69,7 @@ class SwitchUnknownEdidError(SwitchOperationError):
 # =====
 class Switch:  # pylint: disable=too-many-public-methods
     __X_EDIDS          = "edids"
+    __X_DUMMIES        = "dummies"
     __X_COLORS         = "colors"
     __X_PORT_NAMES     = "port_names"
     __X_ATX_CP_DELAYS  = "atx_cp_delays"
@@ -75,7 +77,7 @@ class Switch:  # pylint: disable=too-many-public-methods
     __X_ATX_CR_DELAYS  = "atx_cr_delays"
 
     __X_ALL = frozenset([
-        __X_EDIDS, __X_COLORS, __X_PORT_NAMES,
+        __X_EDIDS, __X_DUMMIES, __X_COLORS, __X_PORT_NAMES,
         __X_ATX_CP_DELAYS, __X_ATX_CPL_DELAYS, __X_ATX_CR_DELAYS,
     ])
 
@@ -105,6 +107,12 @@ class Switch:  # pylint: disable=too-many-public-methods
         if save:
             self.__save_notifier.notify()
 
+    def __x_set_dummies(self, dummies: Dummies, save: bool=True) -> None:
+        self.__chain.set_dummies(dummies)
+        self.__cache.set_dummies(dummies)
+        if save:
+            self.__save_notifier.notify()
+
     def __x_set_colors(self, colors: Colors, save: bool=True) -> None:
         self.__chain.set_colors(colors)
         self.__cache.set_colors(colors)
@@ -236,6 +244,7 @@ class Switch:  # pylint: disable=too-many-public-methods
         self,
         port: int,
         edid_id: (str | None)=None,
+        dummy: (bool | None)=None,
         name: (str | None)=None,
         atx_click_power_delay: (float | None)=None,
         atx_click_power_long_delay: (float | None)=None,
@@ -250,15 +259,16 @@ class Switch:  # pylint: disable=too-many-public-methods
                 edids.assign(port, edid_id)
                 self.__x_set_edids(edids)
 
-            for (key, value) in [
-                (self.__X_PORT_NAMES,     name),
-                (self.__X_ATX_CP_DELAYS,  atx_click_power_delay),
-                (self.__X_ATX_CPL_DELAYS, atx_click_power_long_delay),
-                (self.__X_ATX_CR_DELAYS,  atx_click_reset_delay),
+            for (reset, key, value) in [
+                (None, self.__X_DUMMIES,        dummy),  # None can't be used now
+                ("",   self.__X_PORT_NAMES,     name),
+                (0,    self.__X_ATX_CP_DELAYS,  atx_click_power_delay),
+                (0,    self.__X_ATX_CPL_DELAYS, atx_click_power_long_delay),
+                (0,    self.__X_ATX_CR_DELAYS,  atx_click_reset_delay),
             ]:
                 if value is not None:
                     new = getattr(self.__cache, f"get_{key}")()
-                    new[port] = (value or None)  # None == reset to default
+                    new[port] = (None if value == reset else value)  # Value or reset default
                     getattr(self, f"_Switch__x_set_{key}")(new)
 
     # =====
@@ -375,7 +385,7 @@ class Switch:  # pylint: disable=too-many-public-methods
         prevs = dict.fromkeys(self.__X_ALL)
         while True:
             await self.__save_notifier.wait()
-            while (await self.__save_notifier.wait(5)):
+            while not (await self.__save_notifier.wait(5)):
                 pass
             while True:
                 try:
diff --git a/kvmd/apps/kvmd/switch/chain.py b/kvmd/apps/kvmd/switch/chain.py
index 7137f5b9..4bd9b4eb 100644
--- a/kvmd/apps/kvmd/switch/chain.py
+++ b/kvmd/apps/kvmd/switch/chain.py
@@ -34,6 +34,7 @@ from .lib import aiotools
 from .lib import aioproc
 
 from .types import Edids
+from .types import Dummies
 from .types import Colors
 
 from .proto import Response
@@ -80,6 +81,11 @@ class _CmdSetEdids(_BaseCmd):
     edids: Edids
 
 
+@dataclasses.dataclass(frozen=True)
+class _CmdSetDummies(_BaseCmd):
+    dummies: Dummies
+
+
 @dataclasses.dataclass(frozen=True)
 class _CmdSetColors(_BaseCmd):
     colors: Colors
@@ -189,7 +195,7 @@ class Chain:  # pylint: disable=too-many-instance-attributes
         self.__actual = False
 
         self.__edids = Edids()
-
+        self.__dummies = Dummies({})
         self.__colors = Colors()
 
         self.__units: list[_UnitContext] = []
@@ -225,6 +231,9 @@ class Chain:  # pylint: disable=too-many-instance-attributes
     def set_edids(self, edids: Edids) -> None:
         self.__queue_cmd(_CmdSetEdids(edids))  # Will be copied because of multiprocessing.Queue()
 
+    def set_dummies(self, dummies: Dummies) -> None:
+        self.__queue_cmd(_CmdSetDummies(dummies))
+
     def set_colors(self, colors: Colors) -> None:
         self.__queue_cmd(_CmdSetColors(colors))
 
@@ -348,6 +357,9 @@ class Chain:  # pylint: disable=too-many-instance-attributes
                 case _CmdSetEdids():
                     self.__edids = cmd.edids
 
+                case _CmdSetDummies():
+                    self.__dummies = cmd.dummies
+
                 case _CmdSetColors():
                     self.__colors = cmd.colors
 
@@ -373,7 +385,7 @@ class Chain:  # pylint: disable=too-many-instance-attributes
 
     def __adjust_quirks(self) -> None:
         for (unit, ctx) in enumerate(self.__units):
-            if ctx.state is not None and (ctx.state.version.sw_dev or ctx.state.version.sw >= 7):
+            if ctx.state is not None and ctx.state.version.is_fresh(7):
                 ignore_hpd = (unit == 0 and self.__ignore_hpd_on_top)
                 if ctx.state.quirks.ignore_hpd != ignore_hpd:
                     get_logger().info("Applying quirk ignore_hpd=%s to [%d] ...",
@@ -403,6 +415,7 @@ class Chain:  # pylint: disable=too-many-instance-attributes
                 self.__ensure_config_port(unit, ctx)
                 if self.__actual:
                     self.__ensure_config_edids(unit, ctx)
+                    self.__ensure_config_dummies(unit, ctx)
                     self.__ensure_config_colors(unit, ctx)
 
     def __ensure_config_port(self, unit: int, ctx: _UnitContext) -> None:
@@ -429,6 +442,19 @@ class Chain:  # pylint: disable=too-many-instance-attributes
                     ctx.changing_rid = self.__device.request_set_edid(unit, ch, edid)
                     break  # Busy globally
 
+    def __ensure_config_dummies(self, unit: int, ctx: _UnitContext) -> None:
+        assert ctx.state is not None
+        if ctx.state.version.is_fresh(8) and ctx.can_be_changed():
+            for ch in range(4):
+                port = self.get_virtual_port(unit, ch)
+                dummy = self.__dummies[port]
+                if ctx.state.video_dummies[ch] != dummy:
+                    get_logger().info("Changing dummy flag on port %d on [%d:%d]: %d -> %d ...",
+                                      port, unit, ch,
+                                      ctx.state.video_dummies[ch], dummy)
+                    ctx.changing_rid = self.__device.request_set_dummy(unit, ch, dummy)
+                    break  # Busy globally (actually not but it can be changed in the firmware)
+
     def __ensure_config_colors(self, unit: int, ctx: _UnitContext) -> None:
         assert self.__actual
         assert ctx.state is not None
diff --git a/kvmd/apps/kvmd/switch/device.py b/kvmd/apps/kvmd/switch/device.py
index a057a50d..df532804 100644
--- a/kvmd/apps/kvmd/switch/device.py
+++ b/kvmd/apps/kvmd/switch/device.py
@@ -41,6 +41,7 @@ from .proto import BodySetBeacon
 from .proto import BodyAtxClick
 from .proto import BodySetEdid
 from .proto import BodyClearEdid
+from .proto import BodySetDummy
 from .proto import BodySetColors
 from .proto import BodySetQuirks
 
@@ -164,6 +165,9 @@ class Device:
             return self.__send_request(Header.SET_EDID, unit, BodySetEdid(ch, edid))
         return self.__send_request(Header.CLEAR_EDID, unit, BodyClearEdid(ch))
 
+    def request_set_dummy(self, unit: int, ch: int, on: bool) -> int:
+        return self.__send_request(Header.SET_DUMMY, unit, BodySetDummy(ch, on))
+
     def request_set_colors(self, unit: int, ch: int, colors: Colors) -> int:
         return self.__send_request(Header.SET_COLORS, unit, BodySetColors(ch, colors))
 
diff --git a/kvmd/apps/kvmd/switch/proto.py b/kvmd/apps/kvmd/switch/proto.py
index 2081a4b6..3c39d238 100644
--- a/kvmd/apps/kvmd/switch/proto.py
+++ b/kvmd/apps/kvmd/switch/proto.py
@@ -61,6 +61,7 @@ class Header(Packable, Unpackable):
     CLEAR_EDID = 10
     SET_COLORS = 12
     SET_QUIRKS = 13
+    SET_DUMMY  = 14
 
     __struct = struct.Struct("<BHBB")
 
@@ -96,6 +97,9 @@ class UnitVersion:
     sw:     int
     sw_dev: bool
 
+    def is_fresh(self, version: int) -> bool:
+        return (self.sw_dev or (self.sw >= version))
+
 
 @dataclasses.dataclass(frozen=True)
 class UnitFlags:
@@ -121,11 +125,12 @@ class UnitState(Unpackable):  # pylint: disable=too-many-instance-attributes
     video_hpd:     tuple[bool, bool, bool, bool, bool]
     video_edid:    tuple[bool, bool, bool, bool]
     video_crc:     tuple[int,  int,  int,  int]
+    video_dummies: tuple[bool, bool, bool, bool]
     usb_5v_sens:   tuple[bool, bool, bool, bool]
     atx_busy:      tuple[bool, bool, bool, bool]
     quirks:        UnitQuirks
 
-    __struct = struct.Struct("<HHHBBHHHHHHBBBHHHHBxBB29x")
+    __struct = struct.Struct("<HHHBBHHHHHHBBBHHHHBxBBB28x")
 
     def compare_edid(self, ch: int, edid: Optional["Edid"]) -> bool:
         if edid is None:
@@ -142,7 +147,7 @@ class UnitState(Unpackable):  # pylint: disable=too-many-instance-attributes
             sw_version, hw_version, flags, ch,
             beacons, nc0, nc1, nc2, nc3, nc4, nc5,
             video_5v_sens, video_hpd, video_edid, vc0, vc1, vc2, vc3,
-            usb_5v_sens, atx_busy, quirks,
+            usb_5v_sens, atx_busy, quirks, video_dummies,
         ) = cls.__struct.unpack_from(data, offset=offset)
         return UnitState(
             version=UnitVersion(
@@ -163,6 +168,7 @@ class UnitState(Unpackable):  # pylint: disable=too-many-instance-attributes
             video_hpd=cls.__make_flags5(video_hpd),
             video_edid=cls.__make_flags4(video_edid),
             video_crc=(vc0, vc1, vc2, vc3),
+            video_dummies=cls.__make_flags4(video_dummies),
             usb_5v_sens=cls.__make_flags4(usb_5v_sens),
             atx_busy=cls.__make_flags4(atx_busy),
             quirks=UnitQuirks(ignore_hpd=bool(quirks & 0x01)),
@@ -270,6 +276,18 @@ class BodyClearEdid(Packable):
         return self.ch.to_bytes()
 
 
+@dataclasses.dataclass(frozen=True)
+class BodySetDummy(Packable):
+    ch: int
+    on: bool
+
+    def __post_init__(self) -> None:
+        assert 0 <= self.ch <= 3
+
+    def pack(self) -> bytes:
+        return self.ch.to_bytes() + self.on.to_bytes()
+
+
 @dataclasses.dataclass(frozen=True)
 class BodySetColors(Packable):
     ch:     int
diff --git a/kvmd/apps/kvmd/switch/state.py b/kvmd/apps/kvmd/switch/state.py
index 84f01cfd..92231791 100644
--- a/kvmd/apps/kvmd/switch/state.py
+++ b/kvmd/apps/kvmd/switch/state.py
@@ -27,6 +27,7 @@ import time
 from typing import AsyncGenerator
 
 from .types import Edids
+from .types import Dummies
 from .types import Color
 from .types import Colors
 from .types import PortNames
@@ -48,8 +49,8 @@ class _UnitInfo:
 
 
 # =====
-class StateCache:  # pylint: disable=too-many-instance-attributes
-    __FW_VERSION = 7
+class StateCache:  # pylint: disable=too-many-instance-attributes,too-many-public-methods
+    __FW_VERSION = 8
 
     __FULL    = 0xFFFF
     __SUMMARY = 0x01
@@ -62,6 +63,7 @@ class StateCache:  # pylint: disable=too-many-instance-attributes
 
     def __init__(self) -> None:
         self.__edids = Edids()
+        self.__dummies = Dummies({})
         self.__colors = Colors()
         self.__port_names = PortNames({})
         self.__atx_cp_delays = AtxClickPowerDelays({})
@@ -77,6 +79,9 @@ class StateCache:  # pylint: disable=too-many-instance-attributes
     def get_edids(self) -> Edids:
         return self.__edids.copy()
 
+    def get_dummies(self) -> Dummies:
+        return self.__dummies.copy()
+
     def get_colors(self) -> Colors:
         return self.__colors
 
@@ -226,6 +231,9 @@ class StateCache:  # pylint: disable=too-many-instance-attributes
                                     "reset": self.__atx_cr_delays[port],
                                 },
                             },
+                            "video": {
+                                "dummy": self.__dummies[port],
+                            },
                         })
                     if x_edids:
                         state["edids"]["used"].append(self.__edids.get_id_for_port(port))
@@ -327,6 +335,12 @@ class StateCache:  # pylint: disable=too-many-instance-attributes
         if changed:
             self.__bump_state(self.__EDIDS)
 
+    def set_dummies(self, dummies: Dummies) -> None:
+        changed = (not self.__dummies.compare_on_ports(dummies, self.__get_ports()))
+        self.__dummies = dummies.copy()
+        if changed:
+            self.__bump_state(self.__FULL)
+
     def set_colors(self, colors: Colors) -> None:
         changed = (self.__colors != colors)
         self.__colors = colors
diff --git a/kvmd/apps/kvmd/switch/storage.py b/kvmd/apps/kvmd/switch/storage.py
index 6e3a0a76..f8348009 100644
--- a/kvmd/apps/kvmd/switch/storage.py
+++ b/kvmd/apps/kvmd/switch/storage.py
@@ -39,6 +39,7 @@ from .lib import get_logger
 
 from .types import Edid
 from .types import Edids
+from .types import Dummies
 from .types import Color
 from .types import Colors
 from .types import PortNames
@@ -52,6 +53,8 @@ class StorageContext:
     __F_EDIDS_ALL = "edids_all.json"
     __F_EDIDS_PORT = "edids_port.json"
 
+    __F_DUMMIES = "dummies.json"
+
     __F_COLORS = "colors.json"
 
     __F_PORT_NAMES = "port_names.json"
@@ -74,6 +77,9 @@ class StorageContext:
         })
         await self.__write_json_keyvals(self.__F_EDIDS_PORT, edids.port)
 
+    async def write_dummies(self, dummies: Dummies) -> None:
+        await self.__write_json_keyvals(self.__F_DUMMIES, dummies.kvs)
+
     async def write_colors(self, colors: Colors) -> None:
         await self.__write_json_keyvals(self.__F_COLORS, {
             role: {
@@ -116,6 +122,10 @@ class StorageContext:
         port_edids = await self.__read_json_keyvals_int(self.__F_EDIDS_PORT)
         return Edids(all_edids, port_edids)
 
+    async def read_dummies(self) -> Dummies:
+        kvs = await self.__read_json_keyvals_int(self.__F_DUMMIES)
+        return Dummies({key: bool(value) for (key, value) in kvs.items()})
+
     async def read_colors(self) -> Colors:
         raw = await self.__read_json_keyvals(self.__F_COLORS)
         return Colors(**{  # type: ignore
diff --git a/kvmd/apps/kvmd/switch/types.py b/kvmd/apps/kvmd/switch/types.py
index 33a7f3ad..475ec30f 100644
--- a/kvmd/apps/kvmd/switch/types.py
+++ b/kvmd/apps/kvmd/switch/types.py
@@ -281,6 +281,19 @@ class _PortsDict(Generic[_T]):
         else:
             self.kvs[port] = value
 
+    def __eq__(self, other: "_PortsDict[_T]") -> bool:
+        if not isinstance(other, self.__class__):
+            return False
+        return (self.kvs == other.kvs)
+
+
+class Dummies(_PortsDict[bool]):
+    def __init__(self, kvs: dict[int, bool]) -> None:
+        super().__init__(True, kvs)
+
+    def copy(self) -> "Dummies":
+        return Dummies(self.kvs)
+
 
 class PortNames(_PortsDict[str]):
     def __init__(self, kvs: dict[int, str]) -> None:
diff --git a/switch/switch.uf2 b/switch/switch.uf2
index e5a1725e..6e1346ce 100644
Binary files a/switch/switch.uf2 and b/switch/switch.uf2 differ
diff --git a/web/share/js/kvm/switch.js b/web/share/js/kvm/switch.js
index a33e2fd0..9d261cc4 100644
--- a/web/share/js/kvm/switch.js
+++ b/web/share/js/kvm/switch.js
@@ -459,7 +459,7 @@ export function Switch() {
 
 		let create_content = function(el_parent) {
 			let html = `
-				<table>
+				<table style="width: 100%">
 					<tr>
 						<td>Port name:</td>
 						<td><input
@@ -473,9 +473,33 @@ export function Switch() {
 						<td><select id="__switch-port-edid-selector" style="width: 100%"></select></td>
 					</tr>
 				</table>
-				<hr>
-				<table>
 			`;
+
+			let fw = model.units[model.ports[port].unit].firmware;
+			if (fw.devbuild || fw.version >= 8) {
+				html += `
+					<hr>
+					<table style="width: 100%">
+						<tr>
+							<td>Simulate display on inactive port:</td>
+							<td align="right">
+								<div class="switch-box">
+									<input
+										type="checkbox" id="__switch-port-dummy-switch"
+										${model.ports[port].video.dummy ? 'checked' : ''}
+									/>
+									<label for="__switch-port-dummy-switch">
+										<span class="switch-inner"></span>
+										<span class="switch"></span>
+									</label>
+								</div>
+							</td>
+						</tr>
+					</table>
+				`;
+			}
+
+			html += "<hr><table style=\"width: 100%\">";
 			for (let kv of Object.entries(atx_actions)) {
 				html += `
 					<tr>
@@ -491,6 +515,7 @@ export function Switch() {
 				`;
 			}
 			html += "</table>";
+
 			el_parent.innerHTML = html;
 
 			let el_selector = $("__switch-port-edid-selector");
@@ -521,6 +546,7 @@ export function Switch() {
 				let params = {
 					"port": port,
 					"edid_id": $("__switch-port-edid-selector").value,
+					"dummy": $("__switch-port-dummy-switch").checked,
 					"name": $("__switch-port-name-input").value,
 				};
 				for (let action of Object.keys(atx_actions)) {