IBM 3164 ASCII Manual page 157

Chapter 5. Programming considerations
Using the Keyboard Control commands
Using the Load Alternate Character command
5-70
You can create up to 94 symbols of your own choice and load them onto your
IBM 3164 using the Load Alternate Character command from the host system.
The symbols can include foreign language letters, mathematical and scientific
symbols. and special type of fonts such as bold and italic as shown below.
JI
rr
B
I
In addition, the user can also define shapes or patterns that, when combined
with other such shapes in adjoining character positions on the screen, will
create a graphic representation.
On the display station, each character is represented by a pattern of dots
selected from a matrix. Each dot within the matrix is known as a point.
Characters are normally represented by predefined patterns accessed by
character codes in the data stream that is sent to the display station.
The Alternate Character function allows you to define your own dot patterns
within the character matrices. This function provides storage and accessing
for one set containing 94 user-definable characters or symbols with a line
code value in the range of
X / 21
I
through X/7E/. Each symbol has 8 points
horizontally by 16 points vertically. Each horizontal 8-dot row is divided into
two 4-dot cells, and each character is composed of 32 cells. The following
figure illustrates this situation.
12345678
1
I
I
17
2
3
15
16
2
3
15
16
I
18
!
19
31
32
To display the symbol, just press the corresponding key on your keyboard, and
the Shift key if required. The storage space on your display station which
stores these symbols is erased when you switch the power off on the display
station, use Reset Initial State (RIS) command, or turn the Test/Normal switch
to Test.
(