Specifications

12 AMD Geode™ GeodeROM Functional Specification
Overview
32087C
1.3 Features
GeodeROM provides support to Geode solutions and provides the following initialization and runtime API (application pro-
gramming interface) support:
Legacy Power Management
GeodeROM provides operating system transparent power management.
APM (Advanced Power Management) Real Mode/Protected Mode APIs
The GeodeROM INT 15h API supports the APM 1.2 functions listed in the “Advanced Power Management (APM)
BIOS Interface Specification” available from Microsoft
®
, Intel, and other sources.
ACPI (Advanced Configuration and Power Interface)
GeodeROM provides configuration tables and methods necessary to support the ACPI 1.0b specification available
from Microsoft, Intel, and other sources.
Boot Menu
The system designer can install a menu to activate at POST. The menu provides a list of devices or embedded option
ROMs from which to load potential operating systems. It can be especially useful for systems requiring a recovery
mechanism, or may be used for demonstrating various bootstrap options.
Build Environment is Embedded in ROM Image
The GeodeROM Flash image contains an encoded list of all the user-defined options. Additionally, any overridden file
name and version number is also embedded into the ROM image. This provides a means to determine how the
image was created and makes the debugging process easier.
Enhanced/Large IDE Detection and Configuration
Provides a mechanism that identifies and configures ATA devices, such as IDE drives and CompactFlash devices.
During a power-on or reset sequence, GeodeROM scans the primary and secondary IDE channels for ATA compliant
devices. For each ATA device that is present, GeodeROM performs the ATA “Identify” command to determine the
drive’s geometry, capability, and vendor-specific information. The drive and controller timing registers are configured
for optimal performance based on the combination of drives attached to the system. If a drive’s geometry exceeds the
capability of the standard INT 13h interface, GeodeROM performs CHS (Cylinder/Head/Sector) translation to enable
the legacy operating system to utilize the full capacity of the IDE device.
Bootable CD-ROM Support:
Supports bootable CD-ROM drives off of the IDE interface. Floppy emulation formats are supported.
INT 11h (Equipment List)
Provides a traditional INT 11h service (for operating systems) that determines the number and type of installed IBM
PC/AT-style peripherals.
INT 12h (Get Memory Size)
This GeodeROM interrupt reports to drivers, applications, and operating systems, the amount of base (< 640 KB)
memory available in the system. Typically, this interrupt returns the value 639 (KB), representing the lower ten
segments of real mode RAM minus 1 KB that is allocated to an EBDA (Extended BIOS Data Area).
INT 13h (1.44 MB Floppy Disk Support)
Provides support for a 3.5”/1.44 MB floppy disk drive. The GeodeROM INT 13h floppy disk services enable the user
to read, write, format, verify, and boot from a 1.44 MB floppy diskette. Additionally, GeodeROM provides disk change
line support for the floppy disk drive.
INT 13h (Fixed Disk Services w/IBM Extensions)
In addition to the standard IBM PC/AT-style INT 13h interface, GeodeROM implements the fixed-disk subset of those
INT 13h extensions, defined by the “INT 13h Extensions API” IBM document. These extensions enable GeodeROM,
in conjunction with certain operating systems, to support drives whose capacity exceeds 8.4 GB. GeodeROM also
supports LBA (Logical Block Addressing) for devices larger than 8.4 GB.
INT 14h (Serial Port BIOS Support)
Supports the standard INT 14h interface for initializing, reading and writing data from, and checking the status of the
serial port.