[Info-vax] Whither VMS?

[glen herrmannsfeldt]

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 know the PDP-10 has XCT, and I thought VAX would have one,
but I don't see it in the book.

-- glen