[HECnet] DECnet performance problems (on TOPS-10)

[Paul_Koning at Dell.com]

The pre-cterm remote terminal protocol is not actually a single protocol, but rather a set of protocols specific to the destination OS.   That's why it works well: instead of trying to fit the OS native terminal behavior into a VMS-centric model as is done in Cterm, the rterm protocols simply express a terminal behavior that matches what the OS wants.   The reason Cterm is so bad for TOPS-10 is that there is really nothing that matches -- just for starters, TOPS-10 echoes differently.

The reason you may see failure for one destination OS type and not others is that you're going through completely different code, because you have a different rterm flavor.   There are four flavors (according to the RSTS code I have that implements them): VMS, RSX, RSTS, and TOPS-20.   If I remember right, TOPS-10 uses the RSTS flavor, and RT-11 perhaps does as well.   The RSTS flavor is line oriented (as is Cterm) but echoes TOPS-10 style (which is also RSTS style) not VMS/RSX style.   The VMS and RSX ones are somewhat like Cterm except that they more closely copy the actual set of I/O operations implemented in the terminal drivers of those two.   

You can find implementations of several of these in DECnet/Linux -- if you're having trouble with the standard one on VMS, you might be able to lift the Linux one and port it to VMS... 

	paul

-----Original Message-----
From: owner-hecnet at Update.UU.SE [mailto:owner-hecnet at Update.UU.SE] On Behalf Of gerry77 at mail.com
Sent: Wednesday, August 31, 2011 10:13 PM
To: hecnet at Update.UU.SE
Subject: Re: [HECnet] DECnet performance problems (on TOPS-10)

On Wed, 31 Aug 2011 15:18:25 +0200, you wrote:

SET HOST from a VMS system implies you use CTERM. CTERM is a horrible 
protocol, and only really works fine between VMS systems. Using it to 
connect to anything else usually means you can expect all kind of 
behavior and performance problems.

It might be something else, but I would suspect CTERM as such first 
and foremost.

I think you are quite right: I've just tried a connection using the old RTERM protocol (SET HOST/APP=R) and it works very fine! :-O I'll try anyway to fiddle with a couple of emulator parameters, but...

BTW, since here there are many people that run things like RSX and such, I'll take advantage of this message to ask: did you ever had problems using RTERM? I ask this because I've noticed that SET HOST/APP=R on OpenVMS Alpha
V8.3 bombs with an ACCVIO whenever I try to connect to RSTS or TOPS-10, but not when I use it with VAX/VMS V4.7 (or OpenVMS V7.2 VAX, for that matter).

In other words, I have not so much different versions to try with, but it seems that RTPAD.EXE does not like very old RTERM implementations like ones found in OSes different from VMS, no matter how much vintage it can be.

The system showing this problem is not mine, but at a quick check it appears to have every possible patch kit installed.

This is the relevant image data:

                              image name: "RTPAD"
                              image file identification: "X-10"
                              image file build identification: "XBC4-0080060000"
                              link date/time: 29-JUN-2006 18:18:54.69
                              linker identification: "A13-03"

And this is the error:

%SYSTEM-F-ACCVIO, access violation, reason mask=00, virtual address=0000517000008AA4, PC=0000517000008AA4, PS=0000001B

  Improperly handled condition, image exit forced.
      Signal arguments:     Number = 0000000000000005
                                              Name     = 000000000000000C
                                                                0000000000010000
                                                                0000517000008AA4
                                                                0000517000008AA4
                                                                000000000000001B

      Register dump:
      R0   = 0000000000000003   R1   = 0000000000008F50   R2   = 0000000000008134
      R3   = 0000000000034804   R4   = 000000007FFCF814   R5   = 0000000000009AEF
      R6   = 0000000000000000   R7   = 0000000000000001   R8   = 000000000003481B
      R9   = 000000007FF9DDF0   R10 = 000000007FFA4F28   R11 = 000000007FFCDC18
      R12 = 000000007FFCDA98   R13 = 0000000000005170   R14 = 0000000000008E28
      R15 = 0000000000008E28   R16 = 0000000002A83089   R17 = 0000000000200000
      R18 = FFFFFFFF80903360   R19 = FFFFFFFF820EFA56   R20 = 0000000000000002
      R21 = 0000000000000000   R22 = 000000007AD69A54   R23 = FFFFFFFF801877D0
      R24 = 0000000000000001   R25 = 0000000000000003   R26 = FFFFFFFF8018780C
      R27 = 000000007AD69A54   R28 = 0000000000000006   R29 = 000000007AD69A60
      SP   = 000000007AD69A30   PC   = 0000517000008AA4   PS   = 300000000000001B

Any info about it?

Thanks,
G.