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

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On Mon, 8 Feb 2016 13:27:29 -0000 (UTC)
Simon Clubley via Info-vax <info-vax at rbnsn.com> wrote:

> There is potentially a major difference from the end-user viewpoint if you
> are trying to run real-time applications.
> 
> Let's keep this simple for the benefit of those (_not_ you!) who try to
> confuse the issues here.
> 
> Does the part of the Alpha emulator which is concerned with doing the
> emulation directly talk to the device registers in the hardware on the
> host system ?
> 
> If yes, then it's bare metal. If no, and it talks to some intermediate
> OS's syscalls layer instead of the hardware then it's not bare metal.
> BTW, it doesn't matter if that OS layer is bundled with the emulator or
> not; it's still an intermediate OS layer either way.
> 
> However, if the underlying OS has real-time guarantees (say it's a RTOS
> for example) then you _might_ still be able to meet the real-time
> requirements of the application.
> 
> Don't forget that real-time doesn't mean fast; it means a _guaranteed_
> bounded response time. That's something which a surprising number of
> people don't seem to understand.

Very well said as usual. But is this an issue for OpenVMS users? Is OpenVMS
used for real-time applications?