Specifications
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                            EMS 4.0 SPECIFICATIONS                            

                                 Page Frames                                  

     The bank switched memory chunks are referred to as "page frames".
     These frame consist of four 16K memory blocks mapped into some of
     the normally unused system ROM address area,  0C0000-0EFFFF. Each
     16K page is independent of the other and they can map to discrete
     or overlapping areas of  the  8  megabyte expanded memory address
     area. Most cards allow selection of addresses to prevent conflict
     with  other  cards,  such  as  hard  disk  controllers and  other
     expanded memory boards.

                             Calling the Manager                              

     Applications  programs  communicate with the  EMM  device  driver
     directly via user interrupt 67h.  All  communication  between the
     application program and the driver  bypasses  DOS  completely. To
     call the driver, register AH is loaded with the number of the EMM
     service  requested;  DX  is  loaded  with  the  file handle;  and
     interrupt 67h is called. ES:DI is  used  to pass the address of a
     buffer  or  array  if needed. On return AH contains 0 if the call
     was successful or an error code from 80h to 8Fh if unsuccessful.

 See Also Locating Func/40h Func/4Eh/00h Errors History Programming


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