Specifications

AMD Geode™ GeodeROM Functional Specification 31

Removable Media 32087C

5.0Removable Media

This chapter discusses the support GeodeROM provides for removable media devices, such as floppy disk drives.

5.1 Floppy Disk Drive Support

GeodeROM provides INT 40h and boot support for one 1.44 MB, 3.5” floppy disk drive. As in a traditional boot ROM, only

device 0 (A: drive) is bootable. The proper access method for the INT 40h functions is through the INT 13h service routines.

GeodeROM supports the INT 40h functions listed in Table 5-1 for the floppy drive:

The format of the caller-supplied parameters and return values adheres to standard industry descriptions of the INT 13h

API for floppy drives as outlined in many references, such as the “IBM PC/AT Technical Reference Manual”, and “PC Inter-

rupts”.

5.2 INT 13h Functions Descriptions

This section describes the parameters and return values for each floppy disk-specific INT 13h function in the GeodeROM

device. This section is intended as a guide. Developers interested in extending and/or debugging the GeodeROM INT 13h

interface should consult the documentation listed on the AMD Geode™ Developer Support site.

INT 13h provides the operating system with a series of functions for communicating with the system’s fixed and floppy disk

drives. The INT 13h interface is a cornerstone of PC/AT compatibility because it ensures that software applications such as

DOS and Microsoft

Windows

can read and write disk-based data in a uniform fashion, across a broad variety of architec-

tures.

Table 5-1. INT 40h Functions

Function Number/Name Page Number

Function 00h - Reset Disk Subsystem 32

Function 01h - Get Disk Subsystem Status 33

Function 02h - Read Sectors 34

Function 03h - Write Sectors 35

Function 04h - Verify Sectors 36

Function 05h - Format Track (Floppy Disk) 37

Function 08h - Get Drive Parameters 38

Function 0Dh - Alternate Disk Subsystem Reset 39

Function 15h - Get Disk Type 39

Function 16h - Get Disk Change Status 40

Function 17h - Set Disk Type 41

Function 18h - Set Media Type 42