Microsoft KB Archive/51666

ROM BIOS Drive Parameter Table (INT 13H Service 08H) ID Number: Q51666

3.00 3.10 3.20 3.21 3.22 3.30 3.30a 4.00 4.01 MS-DOS

Summary:

Interrupt 13H Service 08H returns a pointer to a floppy disk drive parameter table in ES:DI if it is successful. Interrupt 1EH uses this parameter table. Information on this table can be found in the following publications:

  Page 197 of “The Peter Norton Programmer’s Guide to the IBM PC,” Peter Norton, Microsoft Press, ISBN #0-914845-46-2   Page 210 of “The New Peter Norton Programmer’s Guide to the IBM PC and PS/2,” Peter Norton and Richard Wilton, Microsoft Press, ISBN #1-55615-131-4   Page 3-23 of the “IBM PS/2 and PC BIOS Interface Technical Reference,” IBM, part number 68X2260 [available from IBM by calling  IBM-PCTB] 

More Information:

The parameter table is 11 bytes long and is composed of the following fields:

Offset Description —— ———–

00 Specify byte 1: step-rate time, head-unload time 01 Specify byte 2: head-load time, DMA mode 02 Wait time until motor turned off (in clock ticks) 03 Bytes per sector: 0=128, 1=256, 2=512, 3=1024 04 Sector number of last sector on track 05 Gap length between sectors for read/write 06 Data transfer length, used when sector length unspecified 07 Gap length between sectors for format 08 Data value stored in formatted sectors 09 Head-settle time 0A Motor start-up time