ARGS: AH = 01h If the caller is a TSR or device driver, DX = Space needed in the HMA by the caller in bytes If the caller is an application program, DX = FFFFh
RETS: AX = 0001h if the HMA is assigned to the caller, 0000h otherwise
ERRS: BL = 80h if the function is not implemented BL = 81h if a VDISK device is detected BL = 90h if the HMA does not exist BL = 91h if the HMA is already in use BL = 92h if DX is less than the /HMAMIN= parameter
This function attempts to reserve the 64K-16 byte high memory area for the caller. If the HMA is currently unused, the caller's size parameter is compared to the /HMAMIN= parameter on the driver's command line. If the value passed by the caller is greater than or equal to the amount specified by the driver's parameter, the request succeeds. This provides the ability to ensure that programs which use the HMA efficiently have priority over those which do not.