Radio Shack TRS-80, Руководство по обслуживанию, Страница: 18 / 44

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Table 2. VDG Control Register
Table 3
Table 4. AVAILABLE CHARACTERS (00 - 7F)
Control Register Bits DMA Bits Mode Selected
D6 D5 D4 D3 D2 D6 D7
CSS A*/G GMD GM1 GM2
(INT*/EXT)
INV A*/S
0 0 X X 0 0 0 Alphanumerical green
0 0 X X 0 1 0 Alphanumerical inverted green
1 0 X X 0 0 0 Alphanumerical orange
1 0 X X 0 1 0 Alphanumerical inverted orange
X 0 X X 0 X 1 Semigraphics Four
0 1 2 3 4 5 6 7 8 9 A B C D E F
0 - - - - - - - - - - - - - - - -
1 - - - - - - - - - - - - - - - -
2
SPACE
BAR
! “ # $ % & ‘ ( ) * + , - . /
3 0 1 2 3 4 5 6 7 8 9 : ; < = > ?
4 @ A B C D E F G H I J K L M N O
5 P Q R S T U V W X Y Z [ \ ]
➡ ➟
6
7
VDG
PINS
CSS INV Character Color Background Border Display Mode Detail
COLOR
TV SCREEN
VDG DATA BUS COMMENTS
0
0 Green Black 32 Characters
1 Black Green in columns
Black
0
0 Orange Black 16 Characters
1 Black Orange in rows
Black
64 Display elements
in columns
32 Display elements
in rows
Black
x
x
Lx C2 C1 C0 Color
0 x x x Black
1 0 0 0 Green
1 0 0 1 Yellow
1 0 1 0 Blue
1 0 1 1 Red
1 1 0 0 Buff
1 1 0 1 Cyan
1 1 1 0 Magenta
1 1 1 1 Orange
L L
3 2
L L
1 0
one
element
12 dots
8 dots
5
7
1 C C C L L L L
2 1 0 3 2 1 0
0
ASCII code
IN
V
The ALPHANUMERIC INTERNAL mode
uses an internal character generator which
contains the following five dot by seven
dot characters @ A B C D E F G H I J K L
M N O P Q R S T U V W X Y Z [ \ ]
➡ ➟
SP ! ” # $ % & ‘ ( ) * + , - . / 0 1 2 3 4 5 6 7 8
9 : ; < = > ?
The SEMIGRAPHICS FOUR mode uses
an internal “coarse graphics” generator
in which a rectangle (eight dots by twelve
dots) is divided into four equal parts. The
luminance of each part is determined by
a corresponding bit on the VDG data bus.
The color of illummated parts is determined
by three bits. It requires 512 bytes of
display memory.
@
A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z
[
\
]
➡
➟
= INVERTED CHARACTER
- = UNDEFINED