Guardian Application Conversion Guide

TMF Transactions Not Propagated to Device Simulator Process Automatically
Considerations for Migrating Any Application
096047 Tandem Computers Incorporated D–7
Nowait Write Buffer
Integrity
A program using nowait write operations with Guardian procedures might incorrectly
allow the contents of the buffer being written to be altered before completion of the
operation (with an AWAITIO[X] procedure call).
For both C-series systems and D-series systems, it is possible for data to be moved
from a write buffer after a write procedure call finishes executing but before the
AWAITIO procedure finishes executing (thereby completing the operation). If an
application alters the contents of such a buffer before the data is moved, the altered
data might be moved instead of the original data (or the data that is moved might be a
combination of the original data and the altered data).
It is more important for D-series systems than for C-series systems to be certain that
buffers containing data to be written remain unaltered until the write operation is
completed by the AWAITIO[X] procedure.
Note SETMODE 72 does not solve this problem. SETMODE 72 controls the use of buffers for read operations
but not for write operations.
To ensure that your C-series application runs successfully on a D-series system,
modify your application so that buffers containing data to be written remain unaltered
until the AWAITIO procedure completes the write operation.
TMF Transactions Not
Propagated to Device
Simulator Process
Automatically
In D-series systems, unlike C-series systems, device simulator processes (processes
with device subtype 30) no longer have TMF transactions propagated to them as the
default interprocess-message transfer mode. This change makes device simulator
more correct because real devices do not have TMF transactions propagated to them.
Note This change also applies to spooler collectors (subtype 31) and tape simulators, although these two kinds
of processes are not usually user-written.
To ensure that your C-series application runs successfully on a D-series system if it
requires TMF transactions to be propagated to a device simulation process (subtype
30), modify your application to use SETMODE 117 with parameter 1 equal to 0.