Rick:
Yes, I had forgotten about SIO/HIO/TIO and was reminded of those by your
first post. I can't recall if I ever personally wrote a SIO instruction.
Most of the channel programming I ever did was at the EXCP level, so i
don't recall writing a SSCH instruction either.
As for the ISAM compatibility interface in VSAM, I think that went out
around the same time as ICF catalogs came along.
I agree that most vanilla application level programs written for S/360
would probably run on a z10 today. IBM took great pains to maintain
backward compatibility.
Mike Myers
Rick Fochtman wrote:
------------------------------<snip>------------------------------
The 360 instruction set is wholly contained in the z/Series
instruction set and many system constructs were extended in such a way
as to make them backward compatible.
----------------------------<unsnip>-----------------------------
Not strictly true; SIO/HIO/TIO are no more than fond memories today.
There might be a very few others, but these are the ones I remember most.
------------------------------<snip>--------------------------------------------
Some system functions (like the ISAM access method) no longer exist,
and some things you could get away with in the early days (think
OS/360) were closed as security or reliability loopholes in MVS.
----------------------------<unsnip>----------------------------------------
ISAM is no great loss, but I don't know if the ISAM Compatability
Interface is still available to convert ISAM calls to the equivalent
VSAM mechanisms.
---------------------------------<snip>------------------------------------
Most macros are backward compatible as well, although some may require
re-assembling to work correctly today (but offhand, I can't think of
any examples).
----------------------------------<unsnip>--------------------------------
AFAIK, only some macros that require a few specialized systems
services are incompatable. Just about everything that application are
expected to use are pretty much unchanged, or at least compatible.
-----------------------------------<snip>--------------------------------
Some ancient programs like DEBE and Ditto still run on a z/Series
machine under z/OS, although they may have been reworked to do so. I
don't still have any of my ancient programs to try out myself.
-------------------------------------<unsnip>-----------------------------
Any old stand-alone programs that do ANY I/O will need to be reworked,
because of the loss of SIO/TIO/HIO instructions and changes in the
overall architecture in this area. Also programs that expect to use
certain areas of the first 2K of storage.
In my experience, very few surviving OS/360 application programs will
fail on z/10 machines. Providing you have access to the correct
run-time libraries.
Rick
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