Re: except what, is Vax addressing sane today

On 9/21/2024 3:14 PM, John Levine wrote:

According to MitchAlsup1 <mitchalsup@aol.com>:

In the days before <good> branch prediction having a conditional branch
after each instruction that could have an execution problem was an
extremely poor choice. Thus, exceptions were invented (circa 1958).

 Oh, it was worse than that.  There were instructions like "Divide or
Halt" which stopped the computer with an error light on a zero divide.
 

Many (most, nearly all) processor architectures have notoriously
bad exception delivery to a point of control that can deal with
the problem at hand.

 Some of us remember imprecise itnterrupts and the OS/360 S0C0
completion code.
 But you are in general right, it makes more sense to keep the computer
running in the normal case and provide slow ways to recover from
failures and do something else.

 From a programmer's perspective, VAX exception handling was very nice. It may have been high overhead, though.