AM3270/TR3271 Reference Manual

Details of the CRT Protocol
TR3271 Subdevice Protocols
086705 Tandem Computers Incorporated 6–5
SETMODE Functions
The call to SETMODE is as follows:
CALL SETMODE (filenumber , function [, parameter 1 ]
[, parameter 1 ] [, last params ])
SETMODE functions applicable to this protocol are summarized below.
SETMODE 30
allows file-system requests to complete in any order. (Normally, file-system
requests are completed in the order in which they are issued on any particular file
number.) In TR3271, a READ (or CONTROL 22) request should be kept
outstanding at all times because the host may either select the subdevice at any
time or use conversational reply when responding to the text from a WRITE
request.
SETMODE 50
enable or disable COPY. This function allows COPY commands from the host to
be passed to the application process to complete a READ. This function is valid
only when the subdevice has an exclusive OPEN. Setting parameter 1 to a
nonzero value enables COPY commands. Setting parameter 1 to zero disables the
COPY commands. The default is “disable COPY.”
For a COPY command to be passed to the application, one of the following must
be true:
the sending subdevice is the same as the receiving subdevice. The subdevice
must have an exclusive OPEN and it must have COPY enabled.
the sending subdevice and the receiving subdevice have an exclusive OPEN
by the same process(pair), and both must have COPY enabled. Only those
subdevices on the same (logical) control unit as the receiving device will be
searched to find the sending device.
If the application process is acting in an application pass-through capacity, and, if
device addresses are different in TR3271 and AM3270, proper mapping of the
sending device address must be performed. The application process also must
handle the case where the control units of actual physical devices are different
from each other, even though the TR3271 emulated subdevices share a logical
control unit.
SETMODE 51
set-reset status. This function allows an application process to set or reset any or
all status bits for a subdevice. Parameter 2 is used as a control mask, that is, for
each valid status bit, the corresponding bit in TR3271’s status will be set or cleared
if the corresponding bit is set or cleared in parameter 1. If the parameter 2 bit is