EDA for the VMS operating system
EDA has been implemented for Digital's VMS operating system
(on VAX and Alpha type machines).
EDA is called by typing:
(This might be different on your system).
You may enter any valid DCL command
preceded by a '$' symbol in column 1 of a command line.
From within EDA DCL command lines are limited to 80
characters like any EDA command. After the DCL command has
been executed, control returns to EDA.
In fact EDA uses the
SPAWN mechanism to create a subprocess.
limitations applicable to the SPAWN command apply to this
interface (namely authorization). Initiating a sub-process
means also that you do not change the current user
environment; e.g. a $ SET DEFAULT xxxx changes the default
directory for the sub-process initiated by that command, but
not for the parent process which is running EDA. Therefore a $ SET
DEFAULT done this way does not make sense.
For this reason the facility below has been introduced.
You may change the current directory by typing:
where dirname is the name of the directory conforming to normal
DCL conventions. Note that the [ MUST be the second character on
the EDA command line. (See the previous paragraph for the reason
why SET DEF won't work).
If you enter $ without a command the execution of EDA is
temporarily suspended and may enter any number of DCL commands.
Whenever you wish to return to EDA type LOGOUT and execution
of EDA will resume. The same limitations as above apply.
This interface is not available when running EDA from a command
procedure or in batch mode (because the $ sign is taken as an end
of file condition).
If your process quota does not allow the creation of a sub-process,
the interface is not available.
other exceptions are intercepted by the program; the current
command is aborted and the program expects the next command.
The reason of the exception is explained. Most common
exceptions are divide by zero in program locations where it
is not checked, overflow or underflow. The program performs
checks at instances where division by zero is likely to
occur, however in unlikely locations this is not done,
because in many instances only bad shaped data (e.g. several
constant "variables" in a factor analysis etc) causes such
In batch mode exceptions are not trapped and cause therefore
abnormal termination. The same is true for ctrl/C when EDA is
run from a command procedure.
In interactive mode any interruption of a command either by
control-C keying or any arithmetic exception or other abnormal
conditions not handled bay EDA cause
the command to be aborted as is, no cleanup operation is
performed; therefore in some instances (e.g. while writing a
file etc) unwanted side-effects may occur.
E.g. files retain their current position, therefore a
subsequent operation continues at that point. Some EDA internal
flags may remain set.
As all exceptions are handled by EDA, one of them -
insufficient disk quota - causes a serious problem
if a print file is active; in that case every EDA command
aborts because it attempts to write to the print file, which
causes an exception, i.e. the command aborts. PRINT OFF will
turn printing off. (maybe try $ PURGE first, it often helps])
Append to files
When creating a new file, EDA ask you if an already existing file
may be overwritten (i.e. creating a new version). Under VMS
you may additionally ask to Append (answer A) the output to
the end of the already existing file.
Any EDA command can be interrupted using the ctrl/C key. The
current command is aborted, and the program waits for the
Note that this is a radical operation, i.e. its consequences
are similar to a system specific program interruption (see
above for an explanation).
Print file name
The print file name is time based and prefixed by 'E' and
a suffix .epr is added.
The E(dit) command within the print file post-processor is
active. The EDT editor is called with the current image.
(This is done via a sub-process, therefore the same limitations
apply as for the system interface).
Note the following restrictions, whenever EDA is executed
in non-interactive mode (i.e. commands are not read from
the interactive terminal):
On VMS external file names can be different from EDA internal file names.
System files are handled automatically,
as well as the print file. For all
other files the rules are as follows: if you specify a file name with an
extension that file name is looked up or created.
If no extension is supplied, e.g.
*READ RAWDATA "MYFILE" then the .DAT extension is used automatically, i.e
this command tries to read form a file named MYFILE.DAT.
Note that *READ RAW "MYFILE." (dot added) means a file called MYFILE.
(i.e. a file name without an extension).
VAX specific commands
The following VMS specific commands are available:
STAT SYSTEM CPU
shows machine performance statistics, e.g. CPU time, page
faults and so on. Each call to STAT SYSTEM time resets
the timer. Therefore you might check the performance of
Important: disk quota
EDA uses quite a number of scratch files, which
- depending upon the application - may need disk quota. Therefore
make sure that you have some room left, before calling EDA if
you wish to avoid nasty surprises.
Several VMS specific error messages have been added:
<VMS 1> Exception (illegal operation).
An illegal operation has been attempted the reason is
given by VMS in detail. If after careful examination
the reason cannot be found, it is likely that you have
found a bug in the program. Please report the error
causing command-sequence to the EDA system
administrator. The current command is aborted.
<VMS 2> command aborted.
The current command is aborted. The reason is given in
the preceding message. EDA now waits for a new
<VMS 3> process quota exceeded.
When using a DCL command from the system interface, an
error has occurred. The sub-process could not be created.
<VMS 4> error in directory name.
The directory name specified with $[dirnam] is not correct. This
means that the syntax is not correct. Note that this does
not mean that the directory does not exists (or similar
reasons; this is not checked at that level.