Справочник Пользователя для AMD LX 900@1.5W

AMD Geode™ LX Processors Data Book

361

Display Controller Register Descriptions

33234H

6.6.19

VGA CRT Controller Registers

The CRTC registers are accessed by writing an index value to the CRTC Index register (3B4h or 3D4h) and reading or writ-
ing the register using the CRTC Data register (3B5h or 3D5h). See the description of the I/O Address Select bit in the Mis-
cellaneous Output register (Section 6.6.17.1 on page 356) for more information on the I/O address of the CRTC registers.
The CRT timings are controlled by the CRT Controller registers when the VGA is active. Various third-party VGA adapters
implement these registers differently, and so different cards can produce different timings with the same settings. The set-
tings shown in Table 6-53 are recommended for various VGA modes when programming the CRTC registers.

Note:

The Extended VGA Registers are accessed through the CRTC interface. This section only discusses the base VGA
registers, however. See Section 6.6.23 "VGA Block Extended Registers" on page 384 for more information on the
extended registers.

Table 6-53. CRTC Register Settings

VGA Mode

Index