[Coco] signal/intercept routine in Basic09

[Robert Gault]

Aaron Wolfe wrote:
> It's probably worth noting that the "port closed" signal is not a part
> of standard OS-9, it is a feature of the DriveWire additions we're
> working on.  The signal's value is 4.  It is sent to a process when
> the remote end of a TCPIP connection closes.
>

For what it is worth, Basic09 would trap the error 4.
  ON ERROR GOTO 100
  ERROR 4
  END
100 PRINT"The error was caught."

When this is run, the message is printed. Now the manual indicates that 
there is no real difference between signals and errors. Errors are just 
specific signals. So, if the signal to be caught is coming from 
Drivewire, it does not seem to be getting through to Basic09. That's 
assuming error trapping as above is being used.

It may mean that using syscall to set up an intercept may not work either.