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

[Johnny Billquist]

On 2016-02-08 15:21, lists at openmailbox.org wrote:
> 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?

I don't know how much it might be used in real-time nowadays, but VMS 
certainly have realtime properties and capabilities in a way that Unix 
systems do not.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol