External Disk Interface - SC12 @CHIP-RTOS V1.10

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External Disk Drive

Here is the interface definition for an external disk B: drive .   This interface allows you to add an external B: drive.   This drive must be block (sector) oriented.   Each sector should be 512 bytes long.   The application must provide a software interrupt 0xB1 function to read and write these sectors on this drive.

Maximum disk size is about 2 Gigabytes.

  • Interrupt_0xB0_function_0x01:_Install External Disk
  • Interrupt_0xB0_function_0x02:_Deinstall External Disk

  • Interrupt 0xB0 service 0x01: Install External Disk

    This function will logically install a B: drive.
    Prior to this call the application must provide a disk read/write function installed at interrupt 0xB1.   This installed handler function should expect:

      AX       1 for write, 0 for read.
      BX,DX    Sector number (BX is MSH of unsigned long)
      CX       Number of sectors to read/write
      ES:DI    Segment:Offset of memory area to read/write

    The handler should return 0 in AX if OK.



    An unsigned long with the total number of sectors.   BX holds high word.

    Return Value

    AX is 0 if OK.

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    Interrupt 0xB0 service 0x02: Deinstall External Disk

    Used to deinstall drive B: which was installed before with function 0x01 (above).



    Return Value

    AX =0 success
    AX !=0 failed (may be drive was not installed?)

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