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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