Specifications

70 AMD Geode™ GeodeROM Functional Specification
Non-Removable Media
32087C
Figure 6-1 on page 71 shows the presence of all tables in a system supporting INT 41h, INT 46h, EDD, ROM-based and
FDPT Extensions.
0Ah BYTE Drive Description Byte:
Bit 7 = If set, the system has been configured to perform DWORD-wide transfers for this drive.
Otherwise, the system performs WORD-wide transfers to and from the drive.
Bit 6 = If set, the drive is a CD-ROM device.
Bit 5 = If set, the drive supports removable media.
Bit 4 = If set, the system has configured the drive to operate in LBA mode.
Bit 3 = If set, the BIOS is currently configured to perform logical to physical translation of the
drive's CHS parameters.
Bit 2 = If set, the BIOS is configured to transfer data to and from the drive in multi-sector mode
and the Multi-sector Transfer Count Byte data is valid.
Bit 1 = If set, the system is configured to transfer data to and from the drive via DMA and the
DMA Assignment Byte data is valid.
Bit 0 = If set, the system has configured the drive controller to operate in a fast PIO timing
mode, and the PIO Mode Type Byte is valid.
0Bh 3 BYTEs Reserved: Must be set to 0.
0Eh BYTE Extension Table Revision ID (= 10h for this structure): Contains the revision ID for the exten-
sion table. Currently, the only value defined for this field is 10h.
FDPTs do not replace standard drive parameter tables; the information contained in each table
is mutually exclusive. Instead, these tables allow the operating system to bypass its compara-
tively time-consuming and inaccurate process of snooping drive capabilities on systems that
do not provide these extensions.
Unlike the two standard drive parameter tables in a PC/AT-compatible BIOS, that are available
to applications and operating system enumeration software via the INT 41h and INT 46h vec-
tors, only the system BIOS knows the exact location of the system's fixed disk parameter table
extensions.
Instead of examining drive parameters via interrupt vectors, applications and operating sys-
tems that are capable of managing more than two drives invoke INT 13h Function 48h to
receive a far pointer to the fixed disk parameter table extension for each of the system’s fixed
disks, regardless of whether the appropriate INT 41h and INT 46h vectors are currently avail-
able for the specified drive.
In addition to verifying the FDPTs are present, the calling application or device driver should
retrieve all physical disk information via the extended INT 13h Function 48h. See Section
6.3.3.6 “Function 48h - Extended Get Drive Parameters” on page 60.
0Fh BYTE Checksum of this Extension Table.
Table 6-4. Fixed Disk Parameter Table (FDPT) (Continued)
Offset Size Description