[Info-vax] CentOS has been effectively killed for production use

[Bob Eager]

On Fri, 11 Dec 2020 08:29:30 +0000, David Wade wrote:

> Disabling "one or two" instructions would also be fairly pointless. Its
> relativity simple to fix. When a "z" box (or any of its predecessors)
> executes an undefined instruction a particular behaviours occurs and a
> fault handler is loaded. The fault handler can then simulate the missing
> instructions.
> 
> This was used back in the day to simulate floating point or commercial
> instructions that were options. It still works to this day.

The same was true on some British machines I have used. Lower end 
machines used software floating point (and other stuff) and higher end 
ones did it in hardware.

Such instructions were often known as 'extracodes'.



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