Setting
a filter
program
Advanced Programmer's Command
SET
phantom
devspec
[TOJ
filter
filespec
[USINGJ
[parameters
J
loads the driver or filter specified by filter filespec into memory and
connects it
to
phantom devspec
(a
non-existing device). You must
then use the FILTER command
to
connect the phantom device to a
real device.
The filter filespec can
be
the KSM/FLT program (listed
in
Appendix
I)
or one of your own filter programs.
Once you have
(1)
set a phantom device to a filter, and then (2)
filtered a device to the phantom device, the device is connected to
your filter program. All data input and output to the device is filtered
through your program.
The parameters are values sent
to
the filter program. These
parameters are totally independent of the SET command. They are
determined only by the needs of your filter program.
Example
Suppose you write a filter program named TRAP/FLT to change some
characters sent to *DO, the video display.
First, you need
to
load your TRAP/FLT program and set it to a
phantom device (this example uses *LC as the name of the phantom
device):
SET
*LC
TO
TRAP/FLT
This causes *LC to point to TRAP/FL
T.
Then, you need to use *LC (which points to the TRAP/FLT program)
to filter the data output to the video display:
FI L
TER
*00
*LC
(ENTER)
Now, all data output to the video display is filtered through your filter
program.
SET
*DU
KSM/FLT
USING
FILEDAT/KSM(ENTER)
FI L
TER
*K
I
*DU
(ENTER)
loads the Keystroke Multiply filter into memory and sets it to the
keyboard.
1-112
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