Hardware lines available on DECstation 3100 ?

[Bunpei Matoba]

I'm not familar with both ultrix and DECstation hardware.
However, I'm involved in a project making a real time control system
using a DECstation 3100 and I have to evaluate software performance
prior to designing the whole system.

My interests are;

1. How long does it take to send a message from a process to
 another process in the same machine using a socket inter-process
 communication mechanism?
   Does the message transfer mechanism require delay of micro-second order
 or millisecond order?

2. How long does it take to receive a single packet message from
 another machine via TCP connection on ethernet?

I measured those items before on Multibus-based computers using
a logic analyzer monitoring internal hardware signals.
For example, in order to measure the delay for a message exchange,
I inserted a simple code for changing voltage of a hardware line
just before a "send" system call and just after a "receive" system
call respectively.
By monitoring the H/L state change of the hardware line
connected to a external logic analyzer I could know the precise
delay time between two system calls.
I'd like to apply the simular method to the case of DECstion3100.

Is there any hardware lines which satisfy the following conditions?

 1. The lines are available on a DECstation 3100 machine of standard
   hardware configuration.
 2. The lines are easily found outside of the machine.
   (if it is impossible, inside of the machine OK)
 3. We can easily change a voltage of the lines in a test program by calling 
   c language level functions.  And the change takes place just after
   calling the function within a period shorter than 100 micro-seconds.

I know this question is too "hard" in this newsgroup. 
I would be very happy, however, if anyone could post a reply.
Thank you very much in advance.

                                   bm at sumikin.co.jp
                                   Bunpei Matoba
                                   Computer Engineer
                                   Sumitomo Metal Industries Control &
                                   Engineering Corporation,  JAPAN






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