TAL Programmer's Guide

TAL and C Guidelines
Mixed-Language Programming
096254 Tandem Computers Incorporated 17–11
Memory Models A C program can use the small-memory model or the large-memory model,
depending on the amount of data storage required. The large-memory model is
recommended and is the default setting. All examples in this subsection illustrate the
large-memory model unless otherwise noted.
A TAL program can use any of the following memory combinations, depending on the
application’s needs:
The user data segment
The user data segment and the automatic extended data segment
The user data segment and one or more explicit extended data segments
The user data segment, the automatic extended data segment, and one or more
explicit extended data segments
The following table describes some aspects of memory usage by C and TAL programs.
The rightmost column refers to the upper 32K-word area of the user data segment.
Language
Memory
Model Addressing Data Storage
Upper 32K-Word
Area
C Small 16-bit 32K words Reserved
C Large 32-bit 127.5 megabytes Reserved
TAL Not
applicable
16-bit or
32-bit
64K words (without the CRE), plus
127.5 megabytes in each extended
data segment that is allocated.
Reserved only if
you use the CRE
Any TAL module that uses the upper 32K-word area of the user data segment cannot
run within a C object file that contains the MAIN routine.