2016-08-24[1.3A]    1. Support new AT commands (+PPE, +PPID, +PPPW, +PBR)
                    2. Improve TCP function
                    3. Fix minor bugs
2010-04-22[1.2E]    1. A bug which is related with Timeout parameter has been fixed.
                    2. Handling process for setting wrong IP address (0.0.0.0) has been added.
                    3. A bug which is related with Block size parameter in UDP has been fixed.
                    4. Handling process for expiration of system timer has been added.
                    5. Divided transfer in ATC mode has been fixed.
                    6. LINK LED bug caused by timing error in initialization of RTL8019 has been fixed.
2010-01-14[1.2D]    1. support 2 stop bits
                    2. handling bad environment parameters
2009-09-18[1.2C]    1.serial mark/space parity support
                    2. support mac_id, no_delay, sio_rx_drop
                    3. U2S dynamic peer_ip/port update bug fix
2009-08-21[1.2B]    1. Factory reset bug fix : comment
                    2. modify ip_smart_update : load new subnet mask
                    3. add atc command : +PSE
                    4. modify PPP_MRU size
                    5. apply COD_SEND_ETH_ADDR option to all ezTCP Mode except U2S
                    6. modify minimum Ethernet frame size 62 -> 60
                    7. flush Ethernet frame PAD
                    8. sio1 rx interrupt bug fix
2009-03-27[1.2A]    1. modify TCP STATE MACHINE
                    2. add Product ID in F/W
                    3. support U2S echo
                    4. tcp_rto_count reset bug fix
                    5. add Power Down option : default disable
2008-12-11[1.1L]    1. ATC Serial RX update bug fix
                    2. xfer_timeout bug fix if tcp peer zero window
2008-10-23[1.1k]    1. tx_slow support : 200us delay
                    2. support RESET and Close TCP by ezcfg
                    3. rebuild dhcp machine
                    4. modify sio sending method in U2S mode
                    5. avoid sending udp datagram if header only
                    6. add seed number generation routine
                    7. modify tcp_local_port load method
                    8. U2S interval bug fix
2008-08-07[1.1j]    1. add RTL8019 RX ring buf overflow handler
                    2. rebuild RTL8019 reset sequence and internal ring buf
2008-05-15[1.1I]    1. add atc command : +ppng
                    2. avoid sending ARP request if target IP is zero
                    3. avoid sending packet if target MAC is zero
                    4. xfer_timeout bug fix
2007-09-13[1.1H]    1. UDP multicast support
                    2. PPP down bug fix
2007-06-13[1.1G]    1. Initial release.