Introduction 
to 
3278 Operation 
If 
possible, sit 
at 
a display station 
as 
you read thjs part 
of 
the manual 
so 
that 
you can use the switches and keys 
as 
you read about them. 
If 
your display station 
has a keyboard attached and 
if 
some point is 
not 
clear 
as 
you read, pause for a 
moment 
to 
press the key and watch the result.  Keep in mind, however, 
that 
the 
purpose 
of 
some 
of 
the keys 
is 
to 
notify the host system that your display station 
needs service 
by 
the program.  Pressing any 
of 
these keys when the host system 
is 
ready interrupts the program.  In case you do 
not 
have a keyboard provided with 
your display station, you will only be required 
to 
make initial adjustments to the 
display station (as explained in this section). 
The 
IBM 
3278 Display Station 
is 
shown in Figure 2-1. 
Your 3278 Display Station will have one 
of 
the following six screen formats: 
480 characters 
(12 
lines 
of 
40 characters each), 960 characters 
(I2 
lines 
of 
80 characters each), 1920 characters (24 lines 
of 
80 characters each), 2560 
characters (32 lines 
of 
80 characters each), 3440 characters (43 lines 
of 
80 
characters each), or 3564 characters (271ines 
of 
132 characters each). 
If 
your organization uses 
both 
3275/3277 and 3278 Display Stations, you may 
work with programs 
that 
use 
both 
groups 
of 
display stations.  These programs 
can format the screen 
of 
your 3278 in the same way that they format a 3275 or 
3277 screen.  The 3275 and the 3277, however, have 480- and 1920-character 
screen formats. 
To enable the 3275/3277 programs 
to 
use 
both 
groups 
of 
display stations, the 
960-character 3278 can be formatted as a 480-character display (12 lines 
of 
40 characters each) and the 2560-, 3440-, and 3564-character 3278s can be 
formatted as  1920-character displays (24 lines 
of 
80 characters each).  Some 
programs may use the large format, and other programs may use the smaller 
format.  Therefore, 
if 
you use a 960-, 2560-, 3440-, or 3564-character 3278, 
the display station may switch between the large format and the smaller 
format for different transactions. 
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