[Simh] VAX DZ terminal controller unit?

[Gary Lee Phillips]

On Thu, May 19, 2011 at 6:37 PM, David Holland
<david.w.holland at gmail.com> wrote:
> If all you're wanting to do is simply telnet into the VAX...
>
> Assuming a recent Linux kernel
>
> Bridge devices, and veth type devices will work wonders to get the VAX on
> the LAN.
>
> See:
>
> http://comments.gmane.org/gmane.comp.emulators.simh/420  (or search the
> archives)
>
> As a good starting point....  Obviously, I've used them at one point..
>

Thanks, but the VAX is already on the LAN. That isn't the issue. I
compiled with network support, and the XQ device is attached and
working. The thing is, the host machine has only one NIC. The VAX and
the Linux system share the NIC well enough, each with its own IP
address and MAC address. Connecting from an outside, independent
machine is fine and works for both systems just as if they were
separate, real machines. Both can also originate connections to other
points on the LAN or the Internet. The problem comes when I want to
connect to the virtual VAX from the host Linux system. That cannot be
accomplished by a normal LAN connection because they can't see each
other: when one has control of the NIC, the other does not. I thought
this was the main use of the DZ emulator, as I read the description.
It makes a telnet connection to a port on the host operating system
look like a serial port connection on the VAX side. Thus it allows
direct terminal access from the host machine to the virtualized guest
system. It also works even if the SIMH-VAX module was compiled WITHOUT
actual network support, and I've used it that way in the past.

--Gary