43
CHAPTER 5: Operation
5.5 Contending for Control of the Primary CPU
If you have the optional local control station connected to Unit A as well as the
primary control station connected to Unit B, the users at these stations contend for
keyboard and mouse control of the primary CPU (the one attached to Unit A).
While a user at one station is in control, no keyboard or mouse data from the other
station is accepted. The Num Lock, Caps Lock, and Scroll Lock LEDs on the
keyboard of the station that’s “locked out” will flash in unison (as shown in
Figure 5-2) to show users at that station that they’ll have to wait to access the
primary CPU until the other station’s finished.
Also, depending on which station is controlling the primary CPU, only the
corresponding pair of Unit A’s LEDs will be lit: either the “Primary Control” LEDs
for the station attached to Unit B, or the “Local Control” LEDs for the station
attached to Unit A. (These LEDs are red. The main LED of each pair is labeled
and is on Unit A’s top panel. The auxiliary LED of each pair is unlabeled and is on
the Unit’s right side: The auxiliary “Primary Control” LED is the left-hand one,
while the auxiliary “Local Control” LED is the right-hand one.)
Users at the primary station can try to take keyboard and mouse control of the
primary CPU (and gain audio access to it as well) by selecting it with a hotkey
command (see
Section 5.7
) or—if you enable mouse switching—with their three-
button mouse or wheel mouse (see
Section 5.8
):
• If the primary CPU is being controlled by a user at the local station, these
attempts will fail, although the users at the primary station might be able to see
the primary CPU’s video. This will depend on the setting of position 6 of Unit
A’s DIP switch: If position 6 is OFF (the default setting), the primary CPU’s
video will be broadcast to the primary monitor. But if position 6 is ON, the
Extender will
not
send the primary CPU’s video to the primary monitor if a
user at the local station is controlling the primary CPU (see
Section 4.2.1
).
• If the primary CPU is available (the user at the local station isn’t controlling
it), these attempts will succeed. The Extender will display the primary CPU’s
video on the primary monitor, and will give the users at the primary station
keyboard and mouse control (as well as audio access). They will keep control
until they stop using the keyboard and mouse or select the local CPU or the
nonexistent “CPU zero.” At that point, the Extender will begin counting down
toward its inactivity timeout. (This timeout can be set to 2, 10, 30, or 120
seconds with positions 7 and 8 of Unit A’s DIP switch. The default setting is 2
seconds. See
Section 4.2.1
.) Until the timeout expires, the primary station’s
users can reset it by reselecting the primary CPU or by resuming activity at
their idle keyboard and mouse. Even after the timeout expires, the primary
