[HECnet] FW: More NRT --> VMS and others

From: R. Voorhorst [mailto:R.Voorhorst at swabhawat.com] Sent: Tuesday, 05 May, 2020 12:04 To: 'owner-hecnet at Update.UU.SE' <owner-hecnet at Update.UU.SE> Subject: RE: [HECnet] More NRT --> VMS and others Hi Thomas, I use NRT frequently on the older systems as CTERM does not work well with them; often bursty IO. On VAX/VMS, NRT usually works well, at least as host and cooperates well with Tops10/Tops20 Panda. Also on Rsx11M and Rsts 10.1. Sethost on Tops20 Panda to VMS however does not: sethost Escape character(^Y): Host name: swbv89 ? Communication with VMS not supported by SETHOST Even on OpenVms alpha 8.3 it works to vax, however with connection to tops10/20, the process crashes with an exception. Maybe it could be repaired on Alpha, but I doubt sufficient sources are around. You can test initial connect on Swbv55 on hecnet when it is up, as it is a VAX VMS 7.3 hecnet area router, though you cannot login on it (yet?). Best regards, R.V. From: owner-hecnet at Update.UU.SE <mailto:owner-hecnet at Update.UU.SE> [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Thomas DeBellis Sent: Tuesday, 05 May, 2020 07:14 To: hecnet at Update.UU.SE <mailto:hecnet at Update.UU.SE> Subject: [HECnet] More NRT What's fun about the Tops-20 NRT client (SETHOST) is that it doesn't do much aside from parsing for an escape character and node name. It builds a connection string and checks to make sure the remote system is either a 10 or a 20. Then it twiddles a few things on the terminal (a few more if you're running my changes to handle page mode). Finally, and this is the cool part, it issues an MTOPR% to directly connect the local user's terminal to the open DECnet connection (port 23). Thereafter, the client does nothing until the interrupt character is typed or the connection is broken. So response can be pretty snappy because you are never running in user space; no context switching. The CTERM client on the other hand is reading and writing data and otherwise handling the specifics of the protocol in user space. So, more overhead and more context switching. As an experiment, I removed the checks for Tops-10 and Tops-20 and tried connecting to a few hosts on HECnet. * Tops-20; TOMMYT and TWENEX worked (of course) * Tops-10; VENTI worked * RSX-11+; MIM accepted the connection and broke it as soon as I started typing. * VMS; LEGATO accepted the connection and broke it as soon as I started typing. * RSTS; TRON accepted the connection and then did nothing. It never broke the connection, but never displayed any banner or anything else. It appeared hung. So it would appear that NRT servers only exist on the 36 bit line. Perhaps it's possible to configure the service for other platforms? The first few RSTS systems I tried didn't appear to be online; MEZZO, PLUTO, RSTSE and BITXOT. The few Windows systems I checked didn't appear to be online, either; WXP, MISSY, KIBBEH and WATAN. I'm not sure if that means they refused the connection attempt outright.