Int 21/AH=90h/CX=FFFFh

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PTS-DOS 6.51 & S/DOS 1.0 - DIRECT DISK READ

AH = 90h
CX = FFFFh (for partitions > 32 Mb)
DS:BX -> request block (see #04094)
CX = sector count (for partitions < 32 Mb)
DX = starting sector number
DS:BX -> buffer

Return:
CF set on error AX error code CF clear on success

Notes: This function is supported by Paragon Technology Systems S/DOS 1.0 (and most probably by PTS-DOS 6.51, maybe even earlier).. To access big partitions (> 32 Mb), the CX != FFFFh is not allowed and the buffer must always be used. Otherwise, the system will return error code 0207h.. It is currently unknown if this function is also supported by PhysTechSoft PTS-DOS 6.60, 6.70, or 2000.

See Also: INT 21/AH=91h"PTS" - INT 25h - INT 26h

Format of PTS-DOS & S/DOS disk read/write request block: Offset Size Description (Table 04094) 00h DWORD sector number 04h WORD counter 06h DWORD pointer to buffer

Category: Uncatagorized - Int 21h - P

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