biosdisk

Syntax

#include <bios.h> int biosdisk(int cmd, int drive, int head, int track, int sector, int nsects, void *buffer);

Description

This function interfaces with the BIOS disk service (interrupt 0x13). Please refer to a BIOS reference manual for detailed information about the parameters of this call. The function assumes a sector size of 512 bytes.

The following functions of Int 13h are currently supported:

0 - reset disk subsystem

1 - get status of last operation (see _bios_disk, for possible values)

2 - read one or more sectors

3 - write one or more sectors

5 - format a track

6 - format a cylinder and set bad sector flag

7 - format drive from specified cylinder

8 - get drive parameters

9 - initialize drive parameters

10 - read long sectors

11 - write long sectors

12 - seek to cylinder

13 - alternate fixed disk reset

14 - read sector buffer

15 - write sector buffer

16 - test for drive ready

17 - recalibrate drive

18 - controller RAM diagnostic

19 - controller drive diagnostic

20 - controller internal diagnostic

21 - get DASD type

22 - read disk change line status

23 - set DASD type (pass DASD code in nsects)

24 - set media type for format

The first request with more sectors than will fit in the transfer buffer will cause a DOS buffer to be allocated. This buffer is automatically freed when your application exits. Requests for more sectors than 18 sectors (9K) will fail.

Function 8 returns values in buffer as follows:

byte 0 = sectors per track (bits 0..5), top two bits of cylinder (in bits 6..7)

byte 1 = cylinders (bits 0..7)

byte 2 = number of drives

byte 3 = number of heads

Return Value

The value of AH returned by the BIOS. See _bios_disk, for a detailed list of possible status and error codes.

Portability

ANSI/ISO C	No
POSIX	No

Example

char buffer[512]; if (biosdisk(2, 0x80, 0, 0, 0, 1, buffer)) error("disk");