Int 61 Fn 1B  - Pc/tcp Kernel V2.05+ - "net_read" - Read From The Network  [N]

   AH = 1Bh
   BX = network descriptor
   CX = maximum number of bytes to read
   DX = receive options (see #3136)
   DS:SI -> buffer for data
   ES:DI -> "addr" structure (see #3133) for remote from which to read
       0000h:0000h for any

Return: CF clear if successful
       AX = number of bytes actually read
       DX = ???
   CF set on error
       AX = error code (see #2990 at INT 61"FTP Software")

See Also: INT 61"FTP Software",INT 61/AH=00h"PC/TCP",INT 61/AH=1Ah,INT 61/AH=1Dh

Bitfields for PC/TCP receive options:
Bit(s) Description (Table 3136)
 1 do not remove data from queue, just copy it
 2 do not copy data, just remove it from queue
 5 fail if datagram would be truncated
 6 do not block, return error if no data available

Note:  special case for UDP: if both 1 and 2 set, return number of datagrams