[Info-vax] Baremetal emulators, was: Re: Alpha emulator for OSX

[Johnny Billquist]

On 2016-02-08 17:13, Stephen Hoffman wrote:
> On 2016-02-08 14:21:55 +0000, lists at openmailbox.org said:
>
>> Very well said as usual. But is this an issue for OpenVMS users? Is
>> OpenVMS used for real-time applications?
>
> There are many applications with latent dependencies on timing; that
> will fail when calls operate too quickly or too slowly.  These
> applications are arguably poorly written, but they can and do exist.

All very true, but this is a different can of worms, Stephen.

Linux is not realtime. In fact, you have no idea how long time might 
pass between the execution of one instruction and the next in your 
application. Normally, it will be fast, but there is no bounded limit on 
it. If you depending on a reaction within a bounded time, you are 
playing russian roulette using a host OS like Linux.
And this of course also affect how long "interrupt" latencies your 
machine will appear to have. It might be super fast, and it might take a 
long long time to react to that interrupt. And it varies from time to time.
Because with "next instruction", we're now talking about the next 
instruction in the emulated machine. The actual host will be running and 
executing instructions normally, just that it might be in the bowels of 
Linux for a while...

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
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