Re: [Simh] error

[Mark Pizzolato]

On Tuesday, February 9, 2016 at 2:16 PM, Johnny Billquist wrote:
> On 2016-02-09 22:58, Mark Pizzolato wrote:
> > You may recall that older computers didn’t have a way to
> > programmatically power themselves down.
> 
> Well, this isn't about powering down, but halting...

Well, not really.  The VAX has a HALT instruction and if that was all that was 
needed, it could be executed.  
However nothing defines HALT to do anything but stop executing instructions.  
Well sitting in an infinite loop is sort of like that, but to save power 
someone might want to turn the system off since none of the VAX model systems 
that simh simulators for has any way to programmatically influence power.

The original poster executed the operating command to shutdown the operating 
system.   That would imply that he didn't want it running anymore.  If he 
wanted it to continue running after shutting down, the operating system command 
to reboot the system could have been executed.

> Older and older... It's actually more of a trait of newer computers...
> Back when you had frontpanels and all that stuff, halting the computer were
> considered normal. With the disappearance of most meaningful ways to
> interact with computers at such low levels, halting the computer also went
> away, as it wasn't that useful, and the question the becomes, how would you
> restart it?
> 
> > VMS is one of those systems.
> 
> Er... VAX. VMS is an operating system. :-)
> 
> > When you shutdown a VMS system it closes all files and cleans up
> > everything going on in the operating system then it displays a message
> > which says something like “SYSTEM SHUTDOWN COMPLETE - USE THE
> CONSOLE
> > TO HALT THE SYSTEM” and then it goes into an infinite loop with
> > interrupts disabled.  The simulator detects this condition which will
> > never produce useful results from the simulated system again without
> > operator intervention and allows you to do that.
> 
> Right.
> 
> > Would you want it to behave differently?
> 
> I think simh does a reasonable thing, if you ask me. It was a mistake that the
> VAX didn't standardize how to halt or reboot the machine, but that is not
> simhs fault.

There are absolutely mechanisms to reboot each of the VAX systems which 
simh has simulators for and reboot does work fine on these simulators.

As it turns out, these mechanisms usually use the HALT instruction which 
interacts with some model specific features of the model specific console 
subsystem to effect the reboot.  So, clearly the message which VMS issues
"USE THE CONSOLE TO HALT THE SYSTEM" is actually using the word HALT 
to mean 'turn off' rather than anything which relates to the halt instruction.

> And some VAXen do have the ability to power themselves down as well...
> But it's all very model specific.

If we had a simulator for a VAX model system which had that functionality 
it would be supported.

- Mark

> >
> > *From:*Simh [mailto:simh-boun...@trailing-edge.com] *On Behalf Of
> > *Bill Cunningham
> > *Sent:* Tuesday, February 9, 2016 1:46 PM
> > *To:* simh@trailing-edge.com
> > *Subject:* [Simh] error
> >
> >  After using shutdown on my virtual VMS, it dropped to the simh
> > prompt and had this error.
> >
> > Infinite loop, PC833DC8D3 (BRB ...)
> >
> > and the same hex number were the ... is. What does that mean?
> >
> > Bill
> >
> >
> >
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> >
> 
> --
> Johnny Billquist  || "I'm on a bus
>||  on a psychedelic trip
> email: b...@softjar.se ||  Reading murder books
> pdp is alive! ||  tryin' to stay hip" - B. Idol
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[Simh] error

[Bill Cunningham]

After using shutdown on my virtual VMS, it dropped to the simh prompt and 
had this error.

Infinite loop, PC833DC8D3 (BRB ...) 
and the same hex number were the ... is. What does that mean?

Bill
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Re: [Simh] error

[Johnny Billquist]

On 2016-02-09 22:58, Mark Pizzolato wrote:

You may recall that older computers didn’t have a way to
programmatically power themselves down.


Well, this isn't about powering down, but halting...

Older and older... It's actually more of a trait of newer computers... 
Back when you had frontpanels and all that stuff, halting the computer 
were considered normal. With the disappearance of most meaningful ways 
to interact with computers at such low levels, halting the computer also 
went away, as it wasn't that useful, and the question the becomes, how 
would you restart it?



VMS is one of those systems.


Er... VAX. VMS is an operating system. :-)


When you shutdown a VMS system it closes all files and cleans up
everything going on in the operating system then it displays a message
which says something like “SYSTEM SHUTDOWN COMPLETE - USE THE CONSOLE TO
HALT THE SYSTEM” and then it goes into an infinite loop with interrupts
disabled.  The simulator detects this condition which will never produce
useful results from the simulated system again without operator
intervention and allows you to do that.


Right.


Would you want it to behave differently?


I think simh does a reasonable thing, if you ask me. It was a mistake 
that the VAX didn't standardize how to halt or reboot the machine, but 
that is not simhs fault.


And some VAXen do have the ability to power themselves down as well... 
But it's all very model specific.


Johnny



*From:*Simh [mailto:simh-boun...@trailing-edge.com] *On Behalf Of *Bill
Cunningham
*Sent:* Tuesday, February 9, 2016 1:46 PM
*To:* simh@trailing-edge.com
*Subject:* [Simh] error

 After using shutdown on my virtual VMS, it dropped to the simh
prompt and had this error.

Infinite loop, PC833DC8D3 (BRB ...)

and the same hex number were the ... is. What does that mean?

Bill



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--
Johnny Billquist  || "I'm on a bus
  ||  on a psychedelic trip
email: b...@softjar.se ||  Reading murder books
pdp is alive! ||  tryin' to stay hip" - B. Idol
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Re: [Simh] error

[lists]

On Tue, 9 Feb 2016 13:58:59 -0800
Mark Pizzolato  wrote:

> You may recall that older computers didn't have a way to programmatically
> power themselves down.
> 
> VMS is one of those systems.
> 
> When you shutdown a VMS system it closes all files and cleans up
> everything going on in the operating system then it displays a message
> which says something like "SYSTEM SHUTDOWN COMPLETE - USE THE CONSOLE TO
> HALT THE SYSTEM" and then it goes into an infinite loop with interrupts
> disabled.  The simulator detects this condition which will never produce
> useful results from the simulated system again without operator
> intervention and allows you to do that.
> 
> Would you want it to behave differently?

Personally, no. When I shutdown VMS and I get back to a SIMH prompt that
tells me everything happened the way I wanted/expected. I quit from SIMH
and all is well.

> 
> From: Simh [mailto:simh-boun...@trailing-edge.com] On Behalf Of Bill
> Cunningham Sent: Tuesday, February 9, 2016 1:46 PM
> To: simh@trailing-edge.com
> Subject: [Simh] error
> 
> After using shutdown on my virtual VMS, it dropped to the simh prompt
> and had this error.
> 
> Infinite loop, PC833DC8D3 (BRB ...)
> and the same hex number were the ... is. What does that mean?
> 
> Bill
> 
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[Simh] SIMH and physical hardware

[Zachary Kline]

This is around 50% humorous, but it’s still a thing I’ve been thinking about 
lately. From a newbie’s perspective, all SIMH machines are very similar. The 
worst thing about emulation is that the “feel,” of the original hardware 
doesn’t seem to be there. Simh can emulate tons of hardware from different 
manufacturers, but none of that will tell me what it was like to actually use 
the devices in a physical sense.
As a blind user, I’m doubly interested in this kind of physicality because I 
experience the world through touch and sound. I have little conception of the 
shape or size of many of these notional machines, and they are all reduced to 
various abstractions at a console prompt. It’s hard to imagine a thing I was 
far too young to experience.
I was reminded of an Apple II emulator I saw once, sadly not accessible, which 
made the appropriate disk drive noises in use. Its kind of useless from a  
practical standpoint, but a lot of my interest in these machines isn’t 
practical to begin with. I want to explore an earlier kind of computing, but 
don’t expect to get a job with it or have anything beyond some entertainment. 
I really don’t know what, if anything, can be done to bridge this weird 
disconnect. Actual hardware is probably gradually fading out, and in any case 
probably wouldn’t be accessible from my perspective anyway.

Any thoughts? Apologies for the disjointed post, it’s rather late. ;)
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Re: [Simh] SIMH and physical hardware

[Larry Baker]

Zack,

On Feb 9, 2016, at 9:41 PM, Zachary Kline  wrote:

> Message: 6
> Date: Tue, 9 Feb 2016 21:41:03 -0800
> From: Zachary Kline 
> To: Simh 
> Subject: [Simh] SIMH and physical hardware
> Message-ID: <74262973-d9d8-4eea-98c7-7bb3763e8...@speedpost.net>
> Content-Type: text/plain; charset=utf-8
> 
> This is around 50% humorous, but it’s still a thing I’ve been thinking about 
> lately. From a newbie’s perspective, all SIMH machines are very similar. The 
> worst thing about emulation is that the “feel,” of the original hardware 
> doesn’t seem to be there. Simh can emulate tons of hardware from different 
> manufacturers, but none of that will tell me what it was like to actually use 
> the devices in a physical sense.
> As a blind user, I’m doubly interested in this kind of physicality because I 
> experience the world through touch and sound. I have little conception of the 
> shape or size of many of these notional machines, and they are all reduced to 
> various abstractions at a console prompt. It’s hard to imagine a thing I was 
> far too young to experience.
> I was reminded of an Apple II emulator I saw once, sadly not accessible, 
> which made the appropriate disk drive noises in use.

This reminds me of my early days using PDP-11/34s and RSX-11M.  One sat in the 
same room as the rack with the computer and the disk drives.  RK05s: a 2.4 MB 
14 inch single platter inside a cartridge.  When you went through the 
edit-compile-link steps over and over and over, you could always tell when the 
link step was getting close to finishing by the high pitch chattering of the 
disk drive.  Thanks for the memory.

> Its kind of useless from a  practical standpoint, but a lot of my interest in 
> these machines isn’t practical to begin with. I want to explore an earlier 
> kind of computing, but don’t expect to get a job with it or have anything 
> beyond some entertainment. 
> I really don’t know what, if anything, can be done to bridge this weird 
> disconnect. Actual hardware is probably gradually fading out, and in any case 
> probably wouldn’t be accessible from my perspective anyway.
> 
> Any thoughts? Apologies for the disjointed post, it’s rather late. ;)

Larry Baker
US Geological Survey
650-329-5608
ba...@usgs.gov

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Re: [Simh] SIMH and physical hardware

[lists]

Hi,

I felt a twinge of sorrow reading your post but I am glad you posted it.

There are certainly many people on this list who do or did own actual
hardware but you have to remember many people who used these machines back
in the day never saw the machine or came near it. In most universities and
businesses the machines were kept in what today would be called a server
room, along with air conditioning and cabling either on the floor or under
it (raised floor). The vast majority of users and programmers sat in
terminal rooms or at their desks in cubes or offices and were connected to
the machine by physical cabling. You typically never saw the blinkinlights
or heard the machine or felt the disk drives shaking the floor or the
heat coming off the CPU cabinet. One of the things I remember most is how
loud an IBM 1403 printer is with the hood raised. It's almost to the point
of being unbearable because of how shrill and loud it was.

Again, I'm not saying many people didn't have that experience or that it
isn't important on many levels. I'm just saying the majority of programmers
and end users didn't have that experience so you didn't miss anything
except the comeraderie of being in a terminal room with a bunch of your
friends when the system crashed and hearing everybody groan at the same
time. Or being there in the middle of something when the power failed in
the whole building and losing your work (maybe or maybe not, depending on
what machine you were using). A lot of PDP gear was in small labs where
most students didn't go. At least that's the way it was in the universities
and schools I visited.

The same was true in big companies that used mainframes. The programmers
typically were not allowed in the machine room. The doors had combination
locks and only authorized personnel like operators and IBM's support staff
were allowed in there. Slipping into the machine room with an operator
buddy was grounds for dismissal in some of the places I have worked. Some
data centers in universities and business did have glass walls onto the
floor. But most did not.

The main way that we get the sense today of "wow this is great" is seeing
the terminal displays with the same layouts and prompts as we did in the old
days. For that I am truly sorry you don't have a way you can relate to it.
Imagining what that must be like is painful. On the other hand since you
said you were not around in those days it isn't as bad as it could be.

Bottom line these emulators are keeping old systems and software alive far
past the time that most people can longer use them. You still get a chance
to use old OS, software, and tools and "see" how things worked from that
point of view. You get to use some great quality code the likes of which we
haven't seen in a long time.

Thanks for your post and best regards. Happy vintage computing!


On Tue, 9 Feb 2016 21:41:03 -0800
Zachary Kline  wrote:

> This is around 50% humorous, but it’s still a thing I’ve been thinking
> about lately. From a newbie’s perspective, all SIMH machines are very
> similar. The worst thing about emulation is that the “feel,” of the
> original hardware doesn’t seem to be there. Simh can emulate tons of
> hardware from different manufacturers, but none of that will tell me what
> it was like to actually use the devices in a physical sense. As a blind
> user, I’m doubly interested in this kind of physicality because I
> experience the world through touch and sound. I have little conception of
> the shape or size of many of these notional machines, and they are all
> reduced to various abstractions at a console prompt. It’s hard to imagine
> a thing I was far too young to experience. I was reminded of an Apple II
> emulator I saw once, sadly not accessible, which made the appropriate
> disk drive noises in use. Its kind of useless from a  practical
> standpoint, but a lot of my interest in these machines isn’t practical to
> begin with. I want to explore an earlier kind of computing, but don’t
> expect to get a job with it or have anything beyond some entertainment. I
> really don’t know what, if anything, can be done to bridge this weird
> disconnect. Actual hardware is probably gradually fading out, and in any
> case probably wouldn’t be accessible from my perspective anyway.
> 
> Any thoughts? Apologies for the disjointed post, it’s rather late. ;)
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Re: [Simh] SIMH and physical hardware

[Pontus Pihlgren]

On Tue, Feb 09, 2016 at 09:41:03PM -0800, Zachary Kline wrote:
> 
> Any thoughts? Apologies for the disjointed post, it’s rather late. ;)

To some it is very important. I have a gadget that replaces the floppy 
drive for my Commodore 64. It has an audio jack that plays the sound of 
a real floppy drive! I don't use it, but it shows the effort put in to 
get the right "feeling".

It also emulates the original loading speed if you want :-)

Anyway, I think the best thing you can do is go to see a real machine, 
perhaps at the LCM. It aught to give you a sense of the size, noise and 
smell of old gear.

Keeping a hand on a big old disk when it spins up is a rather nice thing 
:)

/P
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