HP 3000 Manuals HP 3000 Manuals
Migration Choices
Many programs and systems developed and written in SPL are difficult to
replace. To solve this problem, MPE XL offers a range of migration
options for SPL programs:
* Emulate the MPE V environment with Compatibility Mode.
* Convert the program code with the Object Code Translator.
* Convert source programs to a Native Mode language implemented on MPE
XL machines.
Compatibility Mode
SPL programs may be compiled and run on MPE XL machines immediately,
without code changes. They automatically run in Compatibility Mode,
which emulates the MPE V environment. However, emulation lowers
efficiency, sometimes dramatically.
CAUTION Applications running in Compatibility Mode must not execute
privileged instructions; they must call only documented,
callable MPE V/E or subsystem intrinsics. However, they may
enter Privileged Mode and may call MPE V/E privileged intrinsics
from Compatibility Mode.
Object Code Translation
The object code translation program, OCT, which is available on MPE XL
machines, translates many of the MPE V instructions in a compiled object
file into MPE XL instructions. While such a translated program must
still run in Compatibility Mode, it may run faster than an untranslated
program. In general, OCT provides higher performance at the expense of a
larger program size and greater difficulty in debugging. OCT may be
executed with the MPE XL :OCTCOMP command. See the MPE XL Commands
Reference Manual for details.
Conversion to Another Language
Compatibility Mode and object code translation may be sufficient for many
applications. However, any program that requires maximum efficiency or
is enhanced and upgraded regularly should be converted to a language that
generates Native Mode instructions on MPE XL machines. HP C/XL is the
recommended migration language. COBOL II/XL, HP FORTRAN 77/XL, and HP
Pascal/XL, are suitable alternatives.
This migration guide addresses the option of converting SPL source code
to HP C/XL.