Sna Printer Control - IBM 3708 Description

SNA Printer Control
The following paragraphs describe the structure of the SNA session and the SNA
control for printer operations. Details and constraints of subsystem operation are
described under "Local Copy Function" on page 4-81.
Printers attached to the 3708 can
be
configured to operate in one of the three
following modes:
3-52
IBM 3708 Description
System Mode. The printer is logically coupled with a type 1 or 3 SLU as the
principal device; the SLU is in direct session with the PLU. The SLU type is
selected at the time the session is bound using the BIND command and remains
the same throughout the session. In this mode, the printer cannot be used for
local copy functions.
Local Mode. The printer may be used by one or more type 2 SLUs as a
subsidiary device for local copy functions. A copy request may be initiated by
the SLU's PLU (WCC with Start Print= 1) or by the operator using the Print
key. In this mode, the printer cannot
be
used by a type 1 or 3 SL U. An
ACTLU request for the SLU associated with the printer is rejected with sense
code X'0801'.
Shared Mode. Both the SLU type 2 and the SLU type 1 or 3 may compete for
use of the printer. The printer is used by the SLU type 1 or 3 as a principal
device and by the SLU type 2 as a subsidiary device.
When in shared mode, printer contention is allowed to occur between brackets.
When the printer's SLU enters BETB state (or if a session does not exist), the
printer is available for either a local copy from an SLU type 2 or an SLU type 1
or 3 bracket, whichever occurs first. If a local copy function is being performed
for either a single SLU type 2 or a queue of SLU type 2 requests, a BB request
for the type 1 or 3 SLU is rejected with sense code X'0814' (Bracket Reject,
RTR to Follow). When all local copies are completed, the type 1 or 3 SLU
acquires the printer and sends RTR to the PLU. If the type 1 or 3 SLU is in
bracket, the printer is not available for local copy functions. (See "Local Copy
Function" on page 4-81 for details.)