Specifications

36 AMD Geode™ GeodeROM Functional Specification
Removable Media
32087C
5.2.5 Function 04h - Verify Sectors
Description:
Verifies the existence and integrity of the sectors specified by the caller.
Supports:
Fixed disk and floppy disk.
Passed:
Returns:
Special Instructions:
During a floppy diskette verify, the caller ensures the verify operation:
1) Does not cross a 64 KB DMA page boundary (e.g., 2000:0h, 3000:0, etc.).
2) Does not extend past the end of a physical cylinder.
The "IBM PC/AT Technical Reference Manual" specifies the head register as a 4-bit value; the upper four bits of DH are
undefined on this type of system. Newer systems allow for a head value of 0-0FFh, or a maximum of 255 heads. The
INT 13h functions in this type of system are capable of translating between physical (drive reported) and logical cylin-
der, head, sector geometries.
Related Functions:
INT 13h "Function 01h - Get Disk Subsystem Status" on page 33.
INT 13h "Function 02h - Read Sectors" on page 34.
INT 13h "Function 03h - Write Sectors" on page 35.
Parameter Description
AH 04h
AL Sector count
CH Bits [7:0] = Cylinder bits [7:0]
CL Bits [7:6] = Cylinder bits [9:8]
Bits [5:0] = Start sector (1-based)
DH Drive head
DL Drive number
Parameter Description
CF 0 = Success
1 = Failure
AH Status code:
See AH in "Function 01h - Get Disk Subsystem Status" on page 33
AL Number of sectors successfully written