Mozilla v Firefox 406
it used to be when JES crashed it would cause the whole system to crash ... including MVS.
one of the early JES networking problems was that it had jumbled up the design of the JES networking header fields ... and slight changes in JES networking fields could cause the system to crash.
one of the issues on the internal network (larger than the arpanet-internet until about mid-85)
was JES boundary nodes that could crash each other ... different JES releases might have slight variation in networking header fields, sufficient to cause other JES nodes (on the internal network) at slightly different releases to crash.
one of the other early JES networking design problems was that it built its networking node definitions using the old time hasp psuedo device table ... which had 255 entries (one byte index). a typical installation might have 60-80 psuedo devices defined ... leaving something like 160-190 entries for networking node definitions. further exaserbating the problem was that JES would discard all traffice where it didn't recognize either the destination or the origin node.
the internal network had quickly pbutted 255 nodes in the mid-70s (something that the arpanet-internet didn't do until after the great 1-1-83 switch over to internworking protocol) ... and so JES was unuseable on the internal network for other edge-boundary nodes. Eeven as an edge-boundary node, it still had the habit of discarding traffic where it didn't recognize the origin (a MVS system with a large and varied user population found it impossible to juggle the 160 or so network node definitions to keep all the users happy all the time).
the tendency for different JES releases to crash each other resulted in a body of canonicalizing gateway code in the internal network mainstay nodes. This gateway code directly talking to a JES node would be setup with JES header rewrite code specific for that JES release. (in order to prevent one JES node from crashing other JES nodes).
Mozilla v Firefox 407
Touch typing was pretty much the only useful thing I got out of high school, and it would have been useful even if computers hadn't come along. It...
there was an early-on infamous case where JES systems in San Jose (cal.) was causing MVS systems in Hursley (uk) to crash ... and they blaimed it on the gateway code not keeping one JES system from crashing another JES system.