Interrupt 1Eh  Vector of Diskette Controller Parameters

(0:0078h) Dword address points to data base table that is used by BIOS.

Default location is at 0F000:0EFC7h. 11-byte table format:

bytes:

00h 4-bit step rate, 4-bit head unload time

01h 7-bit head load time, 1-bit Not DMA flag

02h 54.9254 ms counts - delay till motor off (37-38 typ)

03h sector size: (bytes/sector)

00h 128 bytes

01h 256 bytes

02h 512 bytes

03h 1024 bytes

04h last sector on track (sectors/cylinder - 8 or 9 typical)

05h gap between sectors on read/write (42 typical)

06h data length for DMA transfers (0FFh typical)

07h gap length between sectors for format (80 typical)

08h sector fill byte for format (0F6h typical)

09h head settle time (in milliseconds) (15 to 25 typical)

DOS 1.0 0

DOS 2.10 15

DOS 3.1 1

10h motor start time (in 1/8 second intervals) (2 to 4 typ.)

DOS 2.10 2

Interrupt 1Eh Vector of Diskette Controller Parameters

note 1) This vector is pointed to the ROM BIOS diskette tables on system

initialization

2) IBM recommends that if this table needs to be modified, it should be

copied into RAM and only the nescessary changes made.

3) The Step Rate, Head Unload Time, Head Load Time, and DMA flag are set

in the 8272, 8272A, or 82072 Floppy Disk Controller Chips using the

SPECIFY command (03h). These parameters are already formated for the

command as they appear in the Diskette Controller Parm table. Values

for the time parameters are dependant on the Data Rate Speed set in the

Data Rate Select Register and are documented in the Intel Product Line

Handbook for Peripherals. For the Step rate higher values result in

faster movement.

4) The Bytes/Sector, Sectors/Cylinder, Gap, and Fill Byte parameters are

used directly from the table by the FORMAT A TRACK command (0Dh or 4Dh)

of the Intel 8272, 8272A, and 82072 floppy disk controllers

5) Sample values for a DOS 3.3 machine are:

00: DF

01: 02

02: 25

03: 02

04: 12

05: 1B

06: FF

07: 54

08: F6

09: 01

10: 08