.TITLE;"GOT YA" - or what you don't know will hurt you
.p
This document describes some common 'features' of RSX (and some DECUS programs)
which frequently cause problems which are difficult to diagnose.
Who said RSX11 is a user friendly system?
.s 2
1. CVL - if the MXF (maximum number of files) of a volume is changed it must
be dismounted and remounted for the change to be effective.
.b
2. Once a database for a driver is loaded, it is never unloaded even though
the driver is unloaded and/or a different version of the driver is reloaded.
If the driver was loaded with VMR then the system must be VMRed from the virgin
RSX11M.TSK in order to load a new driver.
If the driver was not loaded with VMR
then the system may be rebooted to clear out the table and the new driver may
then be loaded.
.b
3. EDT - You must have a UFD (directory) on SY:[x,x] if the file to be edited
is on another device (eg. XX:[x,x]).
In most cases it is preferable to assign SY: to XX: before attempting the edit than
to create unnecessary UFDs on SY:.
.b
4. FMS-F77 - In using Fortran 77 with FMS-11 remember that FMS appends a null
byte to the end of each field in a FGET operation. F77 does not use a null byte
to terminate CHARACTER variables. This difference can cause variables to be
clobbered after an FGET. For example:
.lit

	CHARACTER*8 B,A

	... MISC CODE ...

	CALL FGET(A,ITERM,'FIELDA')	!user enters "12345678" for A
	CALL FGET(B,ITERM,'FIELDB')	!user enters "12345678" for B

.ELI
After execution of the second FGET, instead of variable A containing "12345678"
it will contain "<NULL>2345678" because FMS inserts a null byte after the 8
character field value for "FIELDA". The way we solved the problem is to create
a common block with the FMS field variables seperated by single byte variables.
For example:
.lit

	CHARACTER*8 A,B,C,D
	BYTE X1,X2,X3,X4
	COMMON /FMS/A,X1,B,X2,C,X3,D,X4

.ELI
Another solution is to create each character variable with one more byte than
the field width (in the case above: CHARACTER*9 B,A). This solution was not appropriate for out application.