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AX = 12F0h CX:DX -> user INT 2F handler CF set
Return:
CF clear if successful CX:DX -> previous INT 2F handler CF set on error
Notes: This function is known to be supported by Paragon Technology Systems PTS-DOS 6.51 and S/DOS 1.0, and probably was also supported in earlier releases. It is handled from within the kernel's INT 2Fh dispatcher.. Resident system extensions should call INT 2Fh/12F0h to intercept the INT 2Fh chain. The main idea of this call is to allow them to be moved to the HMA and intercept INT 2Fh without querying A20 state and without interception of the INT2Fh vector. This is why the "Chain2F" variable must be instanced by placing it to the SDA.. On chain entry of the far procedure, CF must be set. All registers except for AX, BP, and DS remain unchanged. If a handler cannot process the call, it must set CF and do a far jump to the previous one in the chain in order to indicate an error. If CF is still set on exit, the call will be ignored.
Category: Other Operating Systems - Int 2Fh - P
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