Category: file/disk compression
INT 21 - DUBLDISK.SYS v2.6 - GET INFO AX = 4404h BL = drive number of DoubleDisk drive (00h = default, 01h = A:, etc.) CX = number of bytes (000Ah-0014h, call ignored otherwise) DS:DX -> data record (see #01530) Return: CF clear if successful AX = number of bytes read CF set on error AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h) Program: DUBLDISK.SYS is the device driver portion of DoubleDisk, a disk expander by Vertisoft Systems, Inc. InstallCheck: for v2.6, scan memory for the signature "FAT 2.6 byte:", which is immediately followed by a data table (see #01531) BUG: VOPT (a disk optimizer by Golden Bow Software) assumes that any driver which returns the "correct" number of bytes when the first word of the buffer for the data record contains the signature value 4444h is DoubleDisk; a workaround is for the non-DoubleDisk driver to return no data if the signature is present SeeAlso: AX=440Dh"DOS 3.2+" Index: installation check;DUBLDISK.SYS