[Info-vax] SimH with framebuffer and hobbyist kit?

Tue Apr 2 19:59:15 EDT 2013

On 2013-04-02, John E. Malmberg <wb8tyw at qsl.network> wrote:
> On 4/2/2013 4:59 PM, Vertis Sidus wrote:
>> On 2013-04-02, Bob Koehler <koehler at eisner.nospam.encompasserve.org> wrote:
>>> In article <slrn3vfsklkdre.pc1.vrtsds at sdf.lonestar.org>, Vertis Sidus <vrtsds at sdf.org> writes:
>>>> I'd like to use DECwindows in an emulated framebuffer, but the only option I
>>>> can find for that is the VAXstation 2000 emulator at
>>>>
>>>>    http://www.9track.net/simh/vax410
>>>>
>>>> This is a rather limited system! From what I've read, it really wants VMS
>>>> 4.x or so, but unfortunately all I have is the current 7.3 hobbyist kit. Is
>>>> it at all possible for VMS 7.3, with DECwindows, to run in this emulator? Or,
>>>> is there another framebuffer emulator option that I don't know about?
>
> The author of that variant of SimH has posted on this forum about it, 
> and you might contact him to get the source.

I may do that, but I'd like to at least try to get it
running as-is first. I haven't done any real programming in
years, so I wouldn't be surprised if it's completely beyond
my ken.

>> Not so lucky in the case of this particular emulator. As
>> near as I can tell, the memory won't go above 16MB, and the
>> only supported storage is two hard drives (RD31, RD32,
>> RD53, or RD54) and a floppy drive. No CD-ROM, of course. I
>> don't even get a tape drive.
>
> Even with those limitations, I think I could get VMS 7.3 to run on it as 
> a LAVC client.

I tried that once, months ago. It died horribly on startup,
because I don't know what I'm doing. :)

That's something I plan to try again, later, after a lot of
research.

> I used to run a farm of VS2000s for a display only application.  The 
> VS2000s network booted VMS.  Oh, and I only had 4 to 6 MB of ram on 
> them.  The actual application being displayed on them ran on a VAX 
> 4000-500.  A fake keyboard plug on them allowed unattended booting.
>
> Way below supported specification, but ran for years.

That's encouraging to hear!

> The problem is that the framebuffer in the emulator is too primitive for 
> DecWindows Motif to support.  You need at least 8 bit graphics.

That's fine. I never really liked Motif anyway. :)

I guess that may be another reason I need an old kit,
though...

> But that still is not good enough.  GTK+ needs at least 24 bit color.
> And your performance will be probably slow.

It hadn't even occurred to me to try to get GTK+ working in
this thing.

> Now some answers to issues raised on your previous posts.
>
> 1. A modern Linux running in a VM using paravirtualized I/O drivers has 
> negligible overhead.
>
> So it is cheap to create a Linux VM to dedicate to running Simh.  Set up 
> for emulated NICs on the VM.  2 for the Linux host, 2 for SimH.
> On the host and the emulated system, you have one NIC each for a private 
> LAN and one for access to the external network.  Using a VM makes this 
> trivial to set up.
>
> You can set up VMs to cause performance loads, but the current Linux 
> kernels detect that they are running in an emulator and just turn many 
> operations over to the host instead of simulating them like was done in 
> ancient times.

Actually, I only mentioned the challenge of getting VMS to
network with the host as a general response to the "why do
you want a framebuffer? just use X!" meme. I've noticed
that when novices try to actually get help with setting X
up, they quite often get a response of "why are you trying
to do something that hard when you've only just gotten
started?"

Networking between VMS and the host is a problem that, for
myself, I've pretty much solved - either with VMs or with
taptap and bridging, depending on the circumstances.

> 2. SimH built with netorking support can handle 512 MB of emulated ram, 
> access to a CD-ROM image controlled by the emulator, and emulated disks, 
> probably up to a terabyte.  I have only used about 10 GB disks myself.

These are beautiful and useful features and I deeply wish
the VS2000 version of SimH had them.

In particular, extending the system memory past 64M (I
think) depends on using the ka655x.bin that comes with
SimH - it's a specially modified version of ka655.bin for
that specific version. I don't think any similar
modification of ka410.bin exists.

And the VS2000 emulator seems to only support four models
of hard drive and two models of floppy drive. There's no
RAanything, much less RAUSER, and the SCSI controller
needed for tape is listed as unimplemented.

Entering anything else gets a "Non-existent parameter"
error.

> 3. For X11, HP TCP/IP does not support SSH tunneling, so you have to 
> lower the security of the X server.  But you only have to do it on your 
> private internal network that is local to your system running a VM.  Or 
> it may be that of the Process Software TCP/IP products can be used to 
> provide SSH tunneling, and they have a hobbyist program.

Is that MultiNet? I actually have that, but I haven't quite
got round to installing it yet. (The kit is huge!)

> 4. You will need to get VMS specific fonts on the X-Server.  The VAX X11 
> software does not have a compatible font server.  The Alpha and IA64 
> versions can serve fonts.  So consider an Alpha emulator.  A Windows VM 
> will use a bit more resources than Linux.  I have not tried running an 
> Alpha emulator on Linux yet.

I've had some success with Alpha emulation on Linux. The
hardest part of setting it up was connecting to the
console. I don't quite remember how I solved that, but
I'm pretty sure I mentioned it here at the time.

As for fonts.. wow. I just don't know. I'll get to that
later, I guess.

>
> Regards,
> -John
> wb8tyw at qsl.network
> Personal Opinion Only
>

Thank you for your insight.

-- 
vrtsds at sdf.org
SDF Public Access UNIX System - http://sdf.org