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

[Jan-Erik Soderholm]

Den 2016-02-09 kl. 04:26, skrev David Froble:
> 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?
>>
>>
>>
>
> If you look around enough, I'd bet you'd find this happening.  Could depend
> on one's definition of real-time.

Very true. Some (not saying here) thinks that "real-time" is something
defined by "reply in under x milliseconds" or somerthing.

Is is very diffrent to run a steel-mill in "real-time" and to
update the local timetable display at the local buss-stop.

Both are "real-time" but with very different requirements when you
come down to actual (milli-) seconds...



>
> But for others, probably not such an issue.
>
> For hobbyists, I'd say no issue at all.