INT 41 - SYSTEM DATA - HARD DISK 0 PARAMETER TABLE ADDRESS [NOT A VECTOR!] Notes: the default parameter table array is located at F000h:E401h in 100% compatible BIOSes; the pointer may be overridden by the hard disk controller's BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. to support drive formats unknown to the ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. not used by some PS/2IBM PS/2, any model models BIOSes which support four hard drives may store the parameter tables for drives 81h-83h immediately following the parameter table pointed at by INT 41, with a separate copy of the drive 81h table for INT 46. The check for such an arrangement is to test whether INT 46 points somewhere other than exactly 16 bytes past INT 41, and the sixteen bytes starting at offset 10h from INT 41 are identical to the sixteen bytes pointed at by INT 46 another arrangement for BIOSes which support four IDE(Integrated Drive Electronics) A type of disk drive interface which essentially extends the PCIBM PC's expansion bus all the way to the drive and places the drive controller on the disk drive itself. See also ESDI. drives is to have four tables pointed at by INT 41 in the order primary master, primary slave, secondary master, and secondary slave, in which case (for example) a system with only primary master and secondary master will have valid tables at offsets 00h and 20h, with garbage (but sectors-per-track = 00h) at offsets 10h and 30h SeeAlso: #03196,INT 13/AH=09h,INT 1E,INT 46"HARD DISK 1",INT 60"Adaptec" SeeAlso: INT C0"AMIAmerican Megatrends, Inc.(American Megatrends, Inc.) A hardware, software and firmware company founded in 1985." Format of fixed disk parameters: Offset Size Description (Table 03196) 00h WORD number of cylinders 02h BYTE number of heads 03h WORD starting reduced write current cylinder (XTIBM PC XT only, 0 for others) 05h WORD starting write precompensation cylinder number 07h BYTE maximum ECC burst length (XTIBM PC XT only) 08h BYTE control byte (see #03197,#03198) 09h BYTE standard timeout (XTIBM PC XT only, 0 for others) 0Ah BYTE formatting timeout (XTIBM PC XT and WD1002 only, 0 for others) 0Bh BYTE timeout for checking drive (XTIBM PC XT and WD1002 only, 0 for others) 0Ch WORD cylinder number of landing zone (ATIBM PC AT and later only) 0Eh BYTE number of sectors per track (ATIBM PC AT and later only) 0Fh BYTE reserved SeeAlso: #00273,#00277 Bitfields for XTIBM PC XT fixed disk control byte: Bit(s) Description (Table 03197) 2-0 drive step speed 000 3ms 100 200ms 101 70ms (default) 110 3ms 111 3ms 5-3 unused 6 disable ECC retries 7 disable access retries Bitfields for ATIBM PC AT fixed disk control byte: Bit(s) Description (Table 03198) 0 unused 1 reserved (0) (disable IRQ(Interrupt ReQuest) A hardware line connected to the interrupt controller chip which signals that a CPU interrupt should be generated.) 2 reserved (0) (no reset) 3 set if more than 8 heads 4 always 0 5 set if manufacturer's defect map on max cylinder+1 (ATIBM PC AT and later only) 6 disable ECC retries 7 disable access retries