Wang 5536 - Page 18

3402
Memory locations are sequentially displayed by addressing memory with
"column" (character) and "row" Cline) counters. Extended rows are
accommodated by indexing the column counter with an offset value supplied
by the CPU.
The display initially presents all 80 characters in the top row. When the
last character has been displayed, the row count is incremented and the
next row of 80 consecutive locations is displayed. When the last character
of the last row is reached, the cycle is repeated. Sixty screen displays
occur per second.
2.3.1.2 Dot Matrix Display (Figure 2-3)
The workstation CRT displays and emph.1s i.zes characters us 1ng a raster scan
display. The display is partitioned into a series of lOxll dot matrices.
Alphanumeric and special characters are created by illuminating a specific
pattern of dots within the matrix associated with each character position.
Specific characters are displayed in an 8x8 portion of the matrix; cursor
and underlines are displayed in the lower 10x2 portion of the matrix.
Most character information is contained in the first seven lines of the
matrix. The eighth 1 ine provides room for descenders, such as the tail of
a comma or the bottom portion of the letter "g." The ninth line, line 118,
may contain half of a blinking cursor. The tenth line, line 119, may
contain an underline or the bottom half of the cursor. The eleventh line,
line #10, provides vertical spacing.
A horizontal group of matrices form a character row. Information within a
matrix is displayed by illuminating an appropriate selection of dots for
each character in a raw during eight successive scan lines.
2
12345678901234~6789
COLUMN--- ... ~ 0-+
DOT-• D1 234~~J~D
"" l -.- ••• -. -+--.-.-.-.-.-~-:~·-+ ..
ROW 4 I . I • • • • CHARACTER
a 5 I , •
6 • : •
I
, • DESCENDER
ROW
,
7
8
9
10
0
,
2
3
4
5
6
7
8
9
10
0
• • • • • je
-.
•
I
•
•
I
•
• • 1
•
• • • • • • • • • UNDERLINE
SPACE
.-,-.__.
i
• •
• • •
• ••
••
I CURSOR
I IBLINKINGI
I I I I I
SPACE
Figure 2-3. Dot Matrix Display
2-4
•
•
•