HP 24SII - Manual (Page 64)

In Port Select Mode B (printer selection at beginning of printing), a
print job is ended only when no characters are received by the Model
24SII DES from the computer for the specified Input Inactivity Timeout
period only.
CAUTION: The Input Inactivity Timeout should not be set to 0 (zero)
seconds (disabled) in Port Select Mode B. Mode B operation cannot
recognize a manual disconnect or clear buffer command until the
current print job is ended via the inactivity timeout period.
If the buffer of the Model 24SII DES is filled to capacity, the unit will
drop the DTR line or send an XOFF to the computer, causing the
computer to stop sending characters until the buffer can accept more
data. In this case, the time that the computer is not sending
characters is not counted as part of the Input Inactivity Timeout.
When a user makes a request to print, the data is sent to the Model
24SII DES and stored in the spooling buffer (standard 1MB, optional
up to 16MB). All users may simultaneously input data to this
dynamically allocated buffer. Therefore, the entire buffer could be
occupied by data from one user, if only one is active, or the buffer
could be simultaneously distributed to all users, maximizing buffer
utilization.
Print jobs are buffered and put into a queue in the same order in
which they were sent to the Model 24SII DES. These print jobs are
then sent to the printer in the same order in which they were queued.
When a computer port LED illuminates, this indicates a connection
between the computer on that port and the buffer of the Model 24SII
DES. When a printer port LED illuminates, this indicates the buffer of
the Model 24SII DES has connected to the printer on that port.