Am 05.02.2018 um 14:42 schrieb Gord Tomlin:
On 2018-02-05 00:54, Jon Perryman wrote:
C is NOT portable. Portable languages must be usable (acceptable) on
a platform's as it exists. zArch became a portable platform after
hardware changes added String (and other) instructions. These
instructions were not added for MVS because we lived without them for
several years.
This is the best example of "motivated reasoning" that I have seen in
this lengthy thread. The world is full of packages written in C (and
many other languages) that can be run on numerous different platforms;
in most cases, all that is required is running a build for that
platform. Conversely, you cannot run HLASM on a computer that does not
support z/Architecture or its ancestors, unless you have a legal or
illegal product that emulates said hardware architecture to run it on.
And, BTW, the historic facts are simply wrong:
IBM had a C compiler for MVS (and VM, I believe) long before there were
string instructions on z/Arch. The implementation of strcpy etc. was slow
in those early days, but some companies (including the ones I worked for)
anyway used C on the mainframe, to take some advantage of the fact that
business critical software like (in our case) insurance math had to be
developed
only once and could be deployed to different platforms (mainframe for
back office applications and servers and laptops for the insurance
agencies).
The strcpy etc. implementation by microcode came later, when customer
pressure on IBM to support C better on the mainframe became higher;
that at least was my impression of IBM's motivation behind that.
More history: Kernighan and Ritchie IMHO had a good knowledge of the
IBM platform and PL/1, for example; one of the first implementations of
C was on S/360. I agree that it is not nice to search for a string
terminator
using TRT, for example (given the length limitation of 256), but anyway:
it can be done, and there are other languages with similar "unfriendly"
concepts or problems that have to solved somehow by the compiler writers
...
You should not mix up language and hardware issues in your reasoning ...
better to keep the two topics separate.
Kind regards
Bernd
