INT 13h,  0Ah (10)       Read Long                                diagnostics

    Reads one or more long sectors into memory from a fixed disk. A long
    sector is a sector of information plus 4 bytes representing the ECC
    code for the sector. This service can be performed on fixed disks
    only.

       On entry:      AH         0Ah
                      AL         Number of sectors to read  (1-127)
                      CH         Cylinder number (10-bit value; upper 2 bits
                                 in CL)
                      CL         Starting sector number
                      DH         Head number
                      DL         Drive number
                      ES:BX      Address of memory buffer

       Returns:       AH         Status of operation (See Service 01h)
                      AL         Number of sectors read
                      CF         Set if error, else cleared

    The service reads the specified number of long sectors starting at the
    specified location (head, cylinder, and track) from a fixed disk into
    a buffer starting at ES:BX.

       Notes:         This service is for diagnostics only. For a more
                      generalized version of the read sector command, see
                      Service 02h, which reads sectors for both diskettes
                      and fixed disks. Also see INT 25h (DOS), which
                      allows the reading of absolute sectors from any type
                      of block device.

                      The cylinder number is a ten-bit quantity (0 through
                      1023). Its most significant two bits are in bits 7
                      and 6 of CL; the remaining eight bits are in CH. The
                      starting sector number fits in the low-order portion
                      (lower 6 bits) of CL.

                      The value returned in AL (number of sectors read)
                      may not give the correct number of sectors, even
                      though there no reading error has occurred. Use the
                      results of the Carry flag and AH (status flag) to
                      determine the status of the operation.

                      The number of sectors to read (AL) can be 127
                      sectors at most.

                      If an error is encountered while reading a sector,
                      use Service 0h to reset the drive and retry the
                      operation. It is recommended that at least 3 retries
                      be attempted before an error is signalled, since the
                      error may have resulted from the diskette motor not
                      being up to speed.

                      Because of the architecture of the DMA channel, an
                      error will occur if the buffer in memory for the
                      sectors overlaps a 64K page boundary. A 64K page
                      boundary is a memory location which is one of the
                      following (10000h, 20000h, 30000h, etc.). Ensure
                      that no part of your buffer falls on this boundary.
                      If it does, create a new buffer or start the buffer
                      just after the boundary.

                      If an error 11h is returned, the data is good but
                      the BIOS is reporting that it was corrected via the
                      ECC error-correcting algorithm. The error may not
                      occur again if the information is written back out.

                      For the AT, XT-286, and PC Convertible, the BIOS
                      executes INT 15h, Service 90h (Device Busy), for the
                      diskette (Type = 01h) and the fixed disk (Type =
                      00h) prior to waiting for the interrupt. INT 15h,
                      Service 91h (Interrupt Complete), is executed upon
                      completion.