INT 60 - Excelan LAN Workplace for DOS 3.5 - API
        ES:BX -> request packet
Return: request packet updated
Notes:  this interrupt is also supported by Beame&Whiteside's BWLWP35 shim,
          which was used in creating this description
        the installation check consists of testing for the WORD 4142h ('AB')
          immediately preceding the interrupt handler
BUG:    because BWLWP35 range-checks only the low byte of the function number,
          and has a fencepost error even in that test, functions 000Bh and
          XX01h-XX0Bh (XX nonzero) branch to random locations
SeeAlso: INT 2F/AX=7A40h

Format of request packet:
Offset  Size    Description
 00h 12 BYTEs   ???
 0Ch    WORD    (return) error code (see below)
 0Eh    DWORD   -> FAR function for ???
 12h    WORD    function number
                0001h ???
                0002h NOP
                0003h NOP
                0004h NOP
                0005h ???
                0006h get ??? record
                0007h NOP
                0008h reset ???
                0009h NOP
                000Ah set ???
        ???
---function 01h---
 20h    BYTE    (call) subfunction (32h-3Bh)
                3Bh non-blocking I/O request (will be tested every clock tick)
 21h    BYTE    (return) error code
                00h successful
                09h invalid connection number
                2Ah bad connection type
                45h ???
---function 01h, subfunction 32h---
 3Ah    WORD    (call) connection type (01h stream, 02h datagram)
---function 01h, subfunction 34h---
 26h    WORD    (call) ???
 28h    WORD    (call) ???
 2Ah    WORD    (call) ???
---function 01h, subfunction 35h---
 1Ah    WORD    (call) connection number???
 26h    WORD    (return) ???
---function 01h, subfunction 36h---
 1Ah    WORD    (call) connection number???
 38h    WORD    ???
---function 01h, subfunction 37h---
 24h    WORD    (return) ???
 26h    WORD    (return) ???
---function 01h, subfunction 38h---
 1Ah    WORD    (call) connection number???
---function 01h, subfunction 3Ah---
 22h    WORD    (call) ???
                667Eh ???
                667Fh ???
 24h    BYTE    (call 667Eh) ???
 24h    WORD    (return 667Fh) ???
---function 01h, subfunction 3Bh---
 0Eh    DWORD   (call) -> function to invoke for I/O or 0000h:0000h
                function called with AX = 0000h
                                     STACK: DWORD -> request packet
                                            WORD 0000h
                        should return STACK unchanged
 1Ah    WORD    (call) connection number???
 21h    BYTE    (return) set to 01h when I/O becomes possible
 22h    BYTE    (call) direction (00h write, 01h read)
 34h    DWORD   (return) -> next pending request packet
---function 05h---
 1Eh    WORD    (call) ???
 20h    WORD    (call) ???
 34h    DWORD   (call) -> ???
---function 06h---
 16h    DWORD   (call) -> buffer for ??? record (see below)
 1Ah    WORD    (call) number of bytes to copy
 22h    WORD    (return) number of bytes transferred
---function 08h---
 14h    WORD    (return) ??? (0001h)
---function 0Ah---
 16h    DWORD   (call) -> WORD ???
 1Ch    WORD    (call) must be 000Ah for BWLWP35

Values for error code:
 0000h  successful
 002Dh  invalid function
 0050h  ???

Format of ??? record:
Offset  Size    Description
 00h    WORD    offset of ???
 02h  4 BYTEs   ???
 06h    DWORD   IP address (big-endian)
 0Ah  6 BYTEs   physical address (big-endian)
        ???

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