4 Jan
2016
4 Jan
'16
7:29 a.m.
On Mon, Jan 04, 2016 at 02:08:17AM +0100, Johnny Billquist wrote:
On 2016-01-04 00:53, Tim Bradshaw <tfb(a)tfeb.org>
wrote:
I don't know if that is a really honest description of the VAX in
general, nor DEC. DEC thrived in the age of the VAX.
However, the CALLS/CALLG and RET instructions were really horrid for
performance. Any clever programmer started using JSB and RSB
instead. as they give you the plain straight forward call and return
semantics without all the extra stuff that the CALL instructions
give.
But, for assembler programmers, the architecture was nice. For
compilers, it's more difficult to do things optimal, and of course,
it took quite a while before hardware designers had the tools, skill
and knowledge how to implement complex instruction sets fast in
hardware. But nowadays, that is definitely not a problem, and it was
more or less already solved by the time of the NVAX chip as well,
which was actually really fast compared to a lot of stuff when it
came out.
Johnny
Yeah, I agree. The VAX was pretty pleasant. I never warmed up to it as
much as I warmed up to the PDP-11 (has to be the most pleasant working
CPU I've used - I say working because NS320xx seemed like it would be
pleasant). I wrote a user level thread library that ran on the VAX and
I had to write the assembler for swtch() and it was pretty easy.
>On 3
Jan 2016, at 23:35, Warren Toomey<wkt(a)tuhs.org> wrote:
>
>Does anybodu have a measure of the expense of function calls under Unix
>on either platform?
>
I don't have the reference to hand, but one of the things Lisp
implementations (probably Franz Lisp in particular) did on the VAX was not to use CALLS:
they could do this because they didn't need to interoperate with C except at known
points (where they would use the C calling conventions). This change made a really
significant difference to function call performance and meant that on call-heavy code Lisp
was often very competitive with C.
I can look up the reference (or, really, ask someone who remembers).
The VAX architecture and its performance horrors must have killed DEC, I guess.