[Info-vax] Whither VMS?

[Bob Eager]

On Mon, 05 Oct 2009 20:15:13 +0000, glen herrmannsfeldt wrote:

> Bob Eager <rde42 at spamcop.net> wrote:
> < On Mon, 05 Oct 2009 15:00:20 -0400, Richard B. Gilbert wrote:
>  
> <> It's not SUPPOSED to happen but Murphy says if it can it will!
> 
> A good rule for computing hardware in general.
>  
> < Yes...in that case, the manufacturer insisted there was no fault. < So
> I wrote a microprogram patch....!
> 
> Reminds me of the story of one IBM computer sometime before S/360.
> 
> For S/360, the EX (execute) instruction is not allowed to execute
> another EX.  An earlier machine allowed it with a loop so tight that
> power cycling the machine wouldn't get out of it. (Core memory including
> the address of the next instruction.) The only way out involved magnets
> and opening the memory box.

I heard that on the Honeywell 516, a very tight loop (single instruction) 
would burn out core. Never tried it though!
> 
> I know the PDP-10 has XCT, and I thought VAX would have one, but I don't
> see it in the book.

No, I don't see it, and I think I would have remembered it since I pretty 
well immersed myself in the VAX instruction set when writing a compiler...




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