2.
Link the printer to *DU, which
in
turn is routed to PRINT/TXT by
issuing the command:
LINK
*PR
*DU
(ENTER)
the device table shows:
*PR
=}
*L0 :
*DU
&
=}
X'0DE3'
*DU
{=}
PRINT/TXT:0
The following link now exists:
*PR
-}
Printer
Driver
(at
X'0DE3')
*PR
-}
*DU
{-}
PRINT/TXT
Everything that TRSDOS sends to
*PR
is also sent to
*DU
and
from there to PRINT/TXT on Drive
0.
Creating
a
Filtered
Link
Creating a filtered link involves the SET and FILTER commands. A
filtered link involves a devices and a filter program which affects the
data that flows to or from the device.
SET prepares a user-created device for the filter connection.
FILTER creates the "logical link" between two devices. The first
device is usually a system device, and the second device is always a
user-created filter device.
~.
Example
To create a filter link you need a filter program.
In
this example we
use the system filter program KSM/FL
T.
Before you issue a SET or FILTER command, be sure to issue a
DEVICE command to see the start-up conditions of the system
devices.
In
this example, we are going to filter the keyboard device.
On start-up, the keyboard is shown
in
the device table as:
*KI
{=
>('0883'
The device table entry shows the place
in
memory (X'0893') where
the driver program that controls the keyboard is located. This memory
address may vary.
To create a KSM filter link between *KI and a user-created device
*DU:
1.
Set *DU to the KSM filter by issuing the command:
5ET *DU K5M/ FLT PRI
NT
/ DAT
(ENTER)
The device table shows:
*KI
<=
>';'0883'
*DU
{#
[Inactive]
X'FF67'
Options:
Type,
KSM
A-104
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