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CHAPTER 4: Operation
4.3.19 S
ET
K
EYBOARD
M
ODE
Keyboard “modes” are electrical signaling protocols that determine how a powered
CPU and keyboard interact. A CPU and keyboard must use the same mode in
order to work with each other. Of the three standard keyboard modes currently in
use, mode number 2 is the one used by the vast majority of CPUs. It is also the
default state of all 101-key and PS/2 keyboards. Mode 1 is used primarily by certain
PS/2 CPUs. Mode 3 is used by RS/6000
®
CPUs, some other UNIX
®
based
computers, and certain specialized servers.
The ServSwitch Professor supports all three of these modes: As it receives signals
from any of the station keyboards, it sends them to the corresponding CPU by
emulating a keyboard of the appropriate mode for that CPU; as it receives signals
for one of the keyboards from the CPU, it sends them to that keyboard by
emulating a CPU of the appropriate mode.
Most CPUs that use keyboard mode 1 or 3 send a “mode command” to the
keyboard at power-up, to put the keyboard in the proper mode. If your CPU is a
mode 1 or mode 3 type, the Professor can use these commands to automatically
detect the CPU’s keyboard mode when you turn on the CPU
after
it has been
cabled to the Professor. However, the Professor doesn’t automatically save this
value; unless you send it a Keep Settings command, it will forget the mode it has
detected when it is turned off or loses power, then default to the most recently
saved setting when it’s powered up again. (For this reason, if you’re using mode 1
or mode 3 CPUs at any of your Professor stations, you will probably want to change
the default keyboard mode of those stations at installation time.)
The ServSwitch Professor’s factory-default keyboard-mode setting is mode 2.
Send the Set Keyboard Mode command to change the keyboard mode if:
• the CPU uses mode 2, but the Professor’s default keyboard-mode setting was
changed previously, or
• you don’t know which mode the CPU uses or the station is set for, but the
keyboard’s behavior makes you suspect that the station’s setting is wrong.
To set the keyboard mode at a particular station, first select that station (see the
Note above
Section 4.3.17
), then press and release the left [Ctrl] key, type [M],
and press the numeral key of the mode number ([1], [2], or [3]). After you enter
this command, enter the Keep Settings command to save the mode setting in
NVRAM, so that the new setting becomes the default value (preserved during
power-down and reloaded at power-up).
