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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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