[Simh] VAX PSI

[Robert G. Schaffrath]

At my firm, we used VAX 2780-3780 to perform dialup 2780 BISYNC 
emulation to a remote data provider (1989-1992 time-frame - 
pre-internet). I wrote a program that would send the dialing 
instructions to the modem over the X.25 port and then wait for the 
carrier signal to be detected. It would then switch to BISYNC and the 
data would start downloading. One thing that was very annoying about the 
2780-3780 software was a bug I hit in either the VAXBI X.25 port driver 
(name of the BI card escapes me) or the VAX 2780-3780 software. We were 
running on a VAX 6330 and anytime I shut the system down, as soon as the 
VAX 2780-3780 daemon process was terminated, the system would BUGCHECK 
on a SPINLOCK issue. I solved the issue by doing some kernel magic and 
marking the process NODELETE early in the shutdown phase. As such, the 
process stayed alive until VMS itself terminated and the BUGCHECK's went 
away.

We started migrating to HP/UX in May 1992 and it was never a priority to 
have DEC fix it. The workaround worked and that was fine with me.