12 Mar
2024
12 Mar
'24
10:41 p.m.
On 3/11/24, Peter Yardley <peter.martin.yardley(a)gmail.com> wrote:
I used the DEC VMS C compiler extensively while I was
at NSWIT. I ported a
lot of Berkley (I think) C code to VMS. Some of their VLSI design suite, KIC
etc. There weren’t a lot of changes to make, the compiler and library was
pretty K&R from what I remember. The usual small header issues applied
The developers of the original DEC VMS C compiler took great pains to
be K&R-friendly by default. There was a strict ANSI C option
available.
There later was a later, C89 compiler produced by Dave Cutler's
DECwest engineering team in Seattle. I think it ran on Unix as well
as VMS. It enforced the C89 standard very strictly--no option for
relaxations or extensions and no K&R compatibility. One customer
described it as the Rush Limbaugh of C compilers--extremely
conservative and you can't argue with it.
VMS IO is a bit different from UNIX IO
Understatement of the century. :-)
but they had a mode (stream I think)
that meant minimal changes to UNIX code.
VMS's device-independent I/O layer is called Record Management
Services (RMS) and as its name implies it is record-oriented. They
did eventually add a stream mode to RMS, but that didn't happen until
well into the 1990s. When DEC C for VMS first came out (ca. 1980)
there was no stream mode in RMS. The C RTL had to implement stream
I/O as a layer on top of RMS. It's fairly easy to build
record-oriented I/O on top of stream I/O but it's very difficult to do
it the other way around. At first release the VMS C RTL's I/O had a
lot of buggy edge conditions. It took them several releases to get
the I/O working properly.
Circa 1985 there was a port of the Bourne shell to VAX/VMS. It of
course needed pipes, and I wrote a pipe pseudo-device driver for VMS.
It supported both stream and record read and write operations.
-Paul W.