ALXD800EEXJ2VD AMD (ADVANCED MICRO DEVICES), ALXD800EEXJ2VD Datasheet - Page 286

• Manufacturer Part Number: ALXD800EEXJ2VD
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of ALXD800EEXJ2VD

• Operating Temperature (min): 0C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

6.5.4
The VGA block provides full hardware support for a VGA
graphics subsystem. It is compatible with the IBM VGA as
defined in the IBM Video Subsystem Technical Reference
manual. This section provides an overview of VGA features
and functions.
6.5.4.1
A VGA “mode” is a programmed VGA configuration defined
by the VGA BIOS that produces a graphics frame buffer
format and a screen image with specific characteristics.
The base VGA function provides coded text modes for text-
based applications, and graphics modes for graphics-
based applications. Many of these modes are compatible
with older graphics adapter standards, such as mono-
chrome display adapter, color graphics adapter, and
enhanced graphics adapter.
Text Modes
There are five text modes defined by VGA BIOS as shown
Table 6-39.
Each of the text modes provides a coded frame buffer con-
sisting of a 16-bit value for each character. The low byte is
the ASCII character code for the character to display, and
the high byte is an attribute byte that determines how the
character is displayed (foreground, background colors,
blink, underline, etc.). There are two formats defined by
BIOS for the attribute byte: color and monochrome as
shown in Table 6-40.
286
BIOS Mode #
0x10
0x11
0x12
0x13
VGA Block Functional Overview
0xD
4, 5
0xE
0xF
6
VGA Modes
33234C
Screen Size in
DWORDs
320 x 200
640 x 200
320 x 200
640 x 200
640 x 400
640 x 350
640 x 480
640 x 480
320 x 200
64 KB
Pixels
Figure 6-15. VGA Frame Buffer Organization
Table 6-41. VGA Graphics Modes
Byte
3
# of Colors
256
16
16
16
16
Byte
4
2
4
2
2
Graphics Modes
The graphics modes defined by VGA BIOS are shown in
Table 6-41.
Mode
BIOS
0, 1
2, 3
Bit
Table 6-40. Text Mode Attribute Byte Format
7
6
5
4
3
2
1
#
7
Byte
Color Definition
Blink
Background Color (R)
Background Color (G)
Background Color (B)
Foreground Intensity/Font
Select
Foreground Color (R)
Foreground Color (G)
Characters
1
Screen
40 x 25
80 x 25
80 x 25
Size in
Table 6-39. VGA Text Modes
Frame Buffer
Packed Pixel
Packed Pixel
Packed Pixel
Format
Planar
Planar
Planar
Planar
Planar
Planar
Byte
AMD Geode™ LX Processors Data Book
0
Attribute
chrome
Mono-
Color
Color
Type
Address
B8000h-
BFFFFh
B8000h-
BFFFFh
B0000h-
B7FFFh
Monochrome Definition
Blink
Background
Background
Background
Foreground Intensity/Font
Select
Foreground
Foreground
Buffer
B8000h-BFFFFh
B8000h-BFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
A0000h-AFFFFh
Buffer Address
Display Controller
Compatibility
CGA
EGA, VGA
MDA