AM3270/TR3271 Reference Manual

Details of the CRT Protocol
TR3271 Subdevice Protocols
6–6 086705 Tandem Computers Incorporated
clear, that status bit will remain as whatever TR3271 currently has as status (see
the status parameters below).
Manipulation of status bits by the application must be performed carefully
because arbitrary changes may cause problems at the host, for example, an
unknown combination of status bits or loss of status when status is expected. For
use in conjunction with status receipt from AM3270, parameter 2 should be set to
%177777 (non-status bits will be ignored) and parameter 1 set to the status bit
pattern received from AM3270 (non-status bits are ignored).
If last params is supplied, last params[0] is set to the count status bit pattern held
by TR3271. In addition, TR3271 returns an indication that it has been sending
WACKs to the host on behalf of a subdevice that does not have a READ (or
CONTROL 22) outstanding (bit 15, the least significant bit, of last params[1]).
The following shows the affect on status by combination of parameter bits for
SETMODE 51:
Current Value Param1 Param2 Result
0-> X-> 0= 0
1-> X-> 0= 1
X -> 0 -> 1 = 0
X -> 1 -> 1 = 1
Current Value
is the value held by TR3271 when the SETMODE is initiated.
Result
is the value held by TR3271 when the SETMODE is complete.
X
value is of no concern.
If TR3271 is selected by the host for a subdevice that is reading and cannot obtain
IOPOOL space to accept the text block(s), TR3271 will send an RVI. When the host
issues a specific poll for status in this instance, “intervention required” status will
be returned.
SETMODE 59
returns the actual count of bytes read as a result of a CONTROL 22 (two-step
READ) completion. See “SETMODE 59 Detail,” below.