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Call EPP BIOS (Revision 7) entry point multiplexor functions with

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Data:
DX = EPP port base I/O address
AH = function
40h
Query Mux
Return:
AH = status (see #00634)
AL = currently-selected port
CH = status flags bit 0: channel locked bit 1: interrupt pending
BH = destroyed
Notes: the PhoenixBIOS v4.0 documentation lists BL as the currently-selected port and AL as the status flags
41h
Query Device Port
Data:
AL = EPP multiplex device port (1-8)
Return:
AH = status (see #00634)
CH = status flags (see #00638)
BX = EPP product/device ID (0000h if undefined)
Notes: The PhoenixBIOS v4.0 documentation lists AL as the status flags and CX as the device ID.
42h
Set Product ID
Data:
AL = EPP multiplex device port (1-8)
CX = EPP product ID
Return:
AH = status (see #00634)
BX = destroyed
50h
Query Daisy Chain
Data:
AL = EPP multiplexor device port (1-8)
Return:
AH = status (see #00634)
CH = status flags:
bit 0 : channel locked
bit 1 : interrupt pending
BL = currently-selected device
BH = EPP daisy chain revision (high nybble = major)
CL = daisy-chain depth (00h if no daisy chain)
ES:DI ASCIZ driver vendor identification string
Notes: The PhoenixBIOS v4.0 documentation lists AH=51h as "Query Daisy Chain" and BL as the multiplexor port; it also lists AL as status flags on return.
51h
Rescan Daisy Chain (dynamically reassign port numbers)
Data:
AL = EPP multiplexor device port (1-8)
Return:
AH = status (see #00634)
BX = destroyed
Notes: The PhoenixBIOS v4.0 documentation lists AH=50h as "Rescan Daisy Chain" and BL as the multiplexor port.
Notes: These functions are only valid if a port multiplexor or daisy chain is present.
PhoenixBIOS 4.0 documents function 50h as "Rescan" and 51h as "Query Daisy Chain".
See Also: #00632,INT 2D/AL=DCh