HP Vectra Technical Reference Manual page 261

On Entry: AH
=
F13_WLSECTORS (03H)
AL
=
number of sectors to transfer
For hard discs the sector range is 1-128 assuming 512 byte sectors
For flexible discs the following formats are recognized:
Media Sector Range
320KB 1-8
360KB 1-9
1.2MB 1-15
DL
=
device number (Flexible
<
80H, Hard disc>
=
80H)
DH
=
head number (0-15 not verified)
CH
=
track/cylinder number (not verified)
For Hard discs the high two bits of CL are the MSB of the cylinder number in
CH, making a 10 bit value. The valid range is therefore 0-1023.
For the flexible discs the valid ranges are:
Media Track Range
320KB 0-39
360KB 0-39
1.2MB 0-79
CL
=
sector number (not verified)
For the hard disc the valid value range is 1-17.
For the flexible disc the values in the Sector Range column are also the valid input
values for this parameter.
ES:BX
=
address of data buffer for transfers
On Exit: AH
=
Return Status Code (See table 8.7)
Registers Altered: AX
F13_VLSECTORS (AH
=
04H)
This function performs a read function without transferring any data. This function ensures that
the track and sector can be located on the disc, that the error correction circuitry (CRC) is
working correctly and that the data can be read. Again, the discussion for F13_RD_SECTORS
applies to this function.
252 Disc