Assembly Language Help (alang.hlp) (Table of Contents; Topic list)
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@ChkDrv Macro
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  Include:   DOS.INC
 
  Syntax:    @ChkDrv [drive]
 
  Summary:   Gets various data about a disk
 
  Argument:  <drive>     8-bit drive number (0 = current, A = 1,
                         B = 2, ...); if none given, current assumed
 
  Returns:   AX     Sectors per cluster; -1 if drive invalid
             BX     Available clusters
             CX     Bytes per sector
             DX     Clusters per drive
 
  Modifies:  AX, BX, CX, DX
 
  See also:  Int 21h Function 36h, @GetDrv
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