49
CHAPTER 4: Operation
4.3.25 S
END
N
ULL
B
YTE
(PS/2 T
YPE
M
ICE
O
NLY
)
Regular PS/2 type mice send control data to CPUs in three-byte increments.
Sometimes, because of electronic transients, unusual power-up effects, or plugging
and unplugging of cables from live equipment, an active CPU in a ServSwitch
Professor system can lose one or two bytes of this control information and get “out
of sync” with the mouse that’s controlling it. In this situation, the mouse might
seem to refuse to move the pointer or cursor, open windows for no reason, or
exhibit other strange behavior. To get the CPU back in sync, send this command
to tell the Professor to send a “null byte” to the CPU’s PS/2 mouse port (this has
no other effect than getting the CPU “caught up”). To issue the Send Null Byte
command, press and release the left [Ctrl] key, then type [N].
If the mouse still isn’t right after you issue this command, the CPU must have
been two bytes out of sync. Issuing the command again should do the trick.
The CPU will be thrown out of sync if it uses a PS/2 mouse and it’s in sync when
you issue this command. Issue this command two more times to get it back in sync
again. This command has no effect on serial mice, or on CPUs that are not
attached to your ServSwitch Professor system through a PS/2 mouse port.
If you have version 9.01 or higher of the Microsoft mouse driver, the CPU should
never get out of sync. Contact Microsoft if you are running DOS or any variety of
Windows and would like to upgrade your Microsoft mouse driver.
4.3.26 I
DENTIFY
ROM
Unfortunately, as with all complex equipment, problems might arise with your
ServSwitch Professor that require the assistance of technical-support personnel.
One of the things technicians might want to know when they attempt to diagnose
and correct your problem is the revision level of the ROM in each of your
ServSwitch Professors. This command causes the currently selected Professor
station to send the four-character “CV
xy
” ROM level—where “CV” is our factory
reference to the Professor,
x
is the major-revision number, and
y
is the minor-
revision number—to the attached CPU as ASCII keyboard data; these characters
will be echoed back to the shared monitor if you are at some type of prompt. (You
must
be at some kind of prompt or screen capable of displaying typed-in keyboard
characters, or you will not see the Professor’s response.) For example, if a station
responds with “CV35,” its ROM is programmed with version 3.5 of the ServSwitch
Professor firmware.
To issue the Identify ROM command, first select the station as described in the
Note above
Section 4.3.17
(although with this command you’re getting
information about the unit rather than configuring it), then press and release the
left [Ctrl] key, then type [I].
