Guardian Application Conversion Guide

General Considerations

Converting to TNS/R Systems

9–2 096047 Tandem Computers Incorporated

Page

00080000 – 00080FFF

00081000 – 00081FFF

00082000 – 00082FFF

00083000 – 000837FF

00083800 – 00083FFF

Addresses (%h)

901

Overflow Results Multiplication and division overflow results are undefined on all Tandem systems.

Furthermore, overflow results of integer multiplication and division instructions

(except LMPY) are incompatible between the TNS and TNS/R systems. The

incompatible instructions are:

IDIV DDIV QDIV LDIV

IMPY DMPY QMPY

Overflow results of addition and subtraction instructions (and LMPY) are compatible

on both systems. The compatible instructions are:

IADD DADD QADD LMPY

ISUB DSUB QSUB

INEG DNEG QNEG

You must test for overflow if your program expects multiplication or division

overflow. Use $OVERFLOW in an IF statement immediately after the operation that

might overflow:

FIXED(0) count, time, result;

CODE (RDE; ANRI %577; SETE); !Disable overflow traps

result := count * time;

IF $OVERFLOW THEN !Test for overflow

result := 0D; !Fix the overflow result