INT 13,A - Read Long Sector (XT & newer)

AH = 0A

AL = number of sectors (1-121 dec.)

CH = track number (0-1023 dec., see below)

CL = sector number (1-17 dec., see below)

DH = head number (0-15 dec.)

DL = fixed drive number (80h=drive 0, 81h=drive 1)

ES:BX = address of buffer

on return:

AH = status (see ~INT 13,STATUS~)

AL = number of sectors actually transferred

CF = 0 if successful

= 1 if error

- BIOS disk reads should be retried at least three times and the

controller should be reset upon error detection

- many good programming references indicate this function is only

available on the AT, PS/2 and later systems, but all hard disk

systems since the XT have this function available

- reads regular data sectors (128-1024 bytes) with an additional

4 byte ECC code included

- a DMA boundary error will occur if the buffer at ES:BX crosses

a 64K segment boundary

- only the disk number is checked for validity

- the parameters in CX change depending on the number of cylinders;

the track/cylinder number is a 10 bit value taken from the 2 high

order bits of CL and the 8 bits in CH (low order 8 bits of track):

¦F¦E¦D¦C¦B¦A¦9¦8¦7¦6¦5¦4¦3¦2¦1¦0¦ CX

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +-------------- sector number

¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ +-------------- high order 2 bits of track number

+-------------------------- low order 8 bits of track number

- see ~INT 13,2~