diff --git a/client/cfg/c64prg.cfg b/client/cfg/c64prg.cfg
index b59f2d5..9cd8359 100644
--- a/client/cfg/c64prg.cfg
+++ b/client/cfg/c64prg.cfg
@@ -13,5 +13,7 @@ SEGMENTS {
     BSS: load = RAM, type = bss;
     ZEROPAGE: load = ZP, type = zp;
     IP65ZP: load = IP65ZP, type = zp;
-    EXEHDR: load = DISCARD, type = ro;
+    EXEHDR: load = DISCARD, type = ro;
+    TCP_VARS: load = RAM, type = bss;
+
 }
diff --git a/client/ip65/tcp.s b/client/ip65/tcp.s
index f2afa17..1d7c968 100644
--- a/client/ip65/tcp.s
+++ b/client/ip65/tcp.s
@@ -10,33 +10,240 @@
 
 .export tcp_init
 .export tcp_process
-.export tcp_add_listener
-.export tcp_remove_listener
-.export tcp_send
+.export tcp_listen
+.export tcp_connect
+.export tcp_callback
+.export tcp_remote_ip
+
+.import ip_calc_cksum
+.import ip_send
+.import ip_create_packet
+.import ip_inp
+.import ip_outp
+.importzp ip_cksum_ptr
+.importzp ip_header_cksum
+.importzp ip_src
+.importzp ip_dest
+.importzp ip_data
+.importzp ip_proto
+.importzp ip_proto_tcp
+.importzp ip_id
+.importzp ip_len
+
+.import copymem
+.importzp copy_src
+.importzp copy_dest
+
+.import cfg_ip
 
 
 .segment "TCP_VARS"
-tcp_cxn_state       =0
-tcp_cxn_local_port  =1
-tcp_cxn_remote_port =3
-tcp_cxn_remote_ip   =5
-tcp_cxn_local_seq   =9
-tcp_cxn_remote_seq  =13
 
-tcp_cxn_entry_size  =17
-tcp_max_connections =10
+tcp_cxn_state_listening   = 1  ;(waiting for an inbound SYN)
+tcp_cxn_state_syn_sent    = 2  ;(waiting for an inbound SYN/ACK)
+  
+
+; tcp packet offsets
+tcp_inp		= ip_inp + ip_data  ;pointer to tcp packet inside inbound ethernet frame
+tcp_outp	= ip_outp + ip_data ;pointer to tcp packet inside outbound ethernet frame
+tcp_src_port	= 0 ;offset of source port field in tcp packet
+tcp_dest_port	= 2 ;offset of destination port field in tcp packet
+tcp_seq		= 4 ;offset of sequence number field in tcp packet
+tcp_ack	= 8 ;offset of acknowledgement field in tcp packet
+tcp_header_length	= 12 ;offset of header length field in tcp packet
+tcp_flags_field	= 13 ;offset of flags field in tcp packet
+tcp_window_size = 14 ; offset of window size field in tcp packet
+tcp_checksum = 16 ; offset of checksum field in tcp packet
+tcp_urgent_pointer = 18 ; offset of urgent pointer field in tcp packet
+tcp_data=20   ;offset of data in tcp packet 
+
+; virtual header
+tcp_vh		= tcp_outp - 12
+tcp_vh_src	= 0
+tcp_vh_dest	= 4
+tcp_vh_zero	= 8
+tcp_vh_proto	= 9
+tcp_vh_len	= 10
+
+;
+tcp_flag_FIN  =1
+tcp_flag_SYN  =2
+tcp_flag_RST  =4
+tcp_flag_PSH  =8
+tcp_flag_ACK  =16
+tcp_flag_URG  =32
+
+
+
+
+.segment "TCP_VARS"
+tcp_state:  .res 1
+tcp_local_port: .res 2
+tcp_remote_port: .res 2
+tcp_remote_ip: .res 4
+tcp_sequence_number: .res 4
+tcp_ack_number: .res 4
+tcp_data_ptr: .res 2
+tcp_data_len: .res 2
+tcp_callback: .res 2
+tcp_flags: .res 1
+.data
+tcp_client_port: .word $0004  ;=$0400 in network byte order
 
-tcp_connections:
-  .res  tcp_max_connections*tcp_cxn_entry_size
 .code
-tcp_add_listener:
-tcp_remove_listener:
-tcp_send:
-tcp_process:
-  lda #NB65_ERROR_FUNCTION_NOT_SUPPORTED
-  sta ip65_error
-  sec
+
 tcp_init:
+  
+  rts
+
+;make outbound tcp connection
+;inputs:
+; tcp_remote_ip:  destination ip address (4 bytes)
+; AX: destination port (2 bytes)
+; tcp_callback: vector to call when data arrives on this connection
+;outputs:
+;   carry flag is set if an error occured, clear otherwise
+tcp_connect:
+  stax  tcp_remote_port  
+  inc   tcp_client_port
+  ldax  tcp_client_port
+  stax  tcp_local_port
+  lda #tcp_cxn_state_syn_sent
+  sta tcp_state
+  lda #tcp_flag_SYN
+  sta tcp_flags
+  ldax  #0
+  stax  tcp_data_len
+  stax  tcp_ack_number
+  stax  tcp_ack_number+2
+  jsr tcp_send_packet
   rts
 
 
+;send a single tcp packet 
+;inputs:
+; tcp_remote_ip: IP address of destination server
+; tcp_remote_port: destination tcp port 
+; tcp_local_port: source tcp port
+; tcp_flags: 6 bit flags
+; tcp_data_ptr: pointer to data to include in this packet
+; tcp_data_len: length of data pointed at by tcp_data_ptr
+;outputs:
+;   carry flag is set if an error occured, clear otherwise
+tcp_send_packet:
+  ldax  tcp_data_ptr
+  stax copy_src			; copy data to output buffer
+	ldax #tcp_outp + tcp_data
+	stax copy_dest
+	ldax tcp_data_len
+	jsr copymem
+
+	ldx #3				; copy virtual header addresses
+:	lda tcp_remote_ip,x
+	sta tcp_vh + tcp_vh_dest,x	; set virtual header destination
+	lda cfg_ip,x
+	sta tcp_vh + tcp_vh_src,x	; set virtual header source
+	dex
+	bpl :-
+
+	lda tcp_local_port		; copy source port
+	sta tcp_outp + tcp_src_port + 1
+	lda tcp_local_port + 1
+	sta tcp_outp + tcp_src_port
+
+	lda tcp_remote_port		; copy destination port
+	sta tcp_outp + tcp_dest_port + 1
+	lda tcp_remote_port + 1
+	sta tcp_outp + tcp_dest_port
+
+  ldx #3				; copy sequence and ack numbers (in reverse order)
+  ldy #0
+:	lda tcp_sequence_number,x
+	sta tcp_outp + tcp_seq,y
+	lda tcp_ack_number,x
+	sta tcp_outp + tcp_ack,y
+  iny
+	dex
+	bpl :-
+
+  lda #$50    ;4 bit header length in 32bit words + 4 bits of zero
+  sta tcp_outp+tcp_header_length
+  lda tcp_flags
+  sta tcp_outp+tcp_flags_field
+  
+	lda #ip_proto_tcp
+	sta tcp_vh + tcp_vh_proto
+
+  ldax  #$1000  
+  stax  tcp_outp+tcp_window_size
+
+	lda #0				; clear checksum
+	sta tcp_outp + tcp_checksum
+	sta tcp_outp + tcp_checksum + 1
+	sta tcp_vh + tcp_vh_zero	; clear virtual header zero byte
+
+	ldax #tcp_vh			; checksum pointer to virtual header
+	stax ip_cksum_ptr
+
+	lda tcp_data_len		; copy length + 20
+	clc
+	adc #20
+	sta tcp_vh + tcp_vh_len + 1	; lsb for virtual header
+	tay
+	lda tcp_data_len + 1
+	adc #0
+	sta tcp_vh + tcp_vh_len		; msb for virtual header
+
+	tax				; length to A/X
+	tya
+
+	clc				; add 12 bytes for virtual header
+	adc #12
+	bcc :+
+	inx
+:
+	jsr ip_calc_cksum		; calculate checksum
+	stax tcp_outp + tcp_checksum
+
+	ldx #3				; copy addresses
+:	lda tcp_remote_ip,x
+	sta ip_outp + ip_dest,x		; set ip destination address
+	dex
+	bpl :-
+
+	jsr ip_create_packet		; create ip packet template
+
+	lda tcp_outp + tcp_data_len + 1	; ip len = tcp data length +20 byte ip header + 20 byte tcp header
+	ldx tcp_outp + tcp_data_len
+	clc
+	adc #40
+	bcc :+
+	inx
+:	sta ip_outp + ip_len + 1	; set length
+	stx ip_outp + ip_len
+
+	ldax #$1234    			; set ID
+	stax ip_outp + ip_id
+
+	lda #ip_proto_tcp		; set protocol
+	sta ip_outp + ip_proto
+
+	jmp ip_send			; send packet, sec on error
+
+
+;listen on the tcp port specified
+; tcp_callback: vector to call when data arrives on specified port
+; AX: set to tcp port to listen on
+tcp_listen:
+  rts
+
+tcp_process:
+;process incoming tcp packet
+;inputs:
+; eth_inp: should contain an ethernet frame encapsulating an inbound tcp packet
+;outputs:
+; carry flag set if any error occured (including if packet not part of 
+; existing connection)
+; carry flag clear if no error
+; if connection was found, an outbound message may be created, overwriting eth_outp
+  rts
diff --git a/client/test/test_tcp.s b/client/test/test_tcp.s
index 4e07ba9..5a0295b 100644
--- a/client/test/test_tcp.s
+++ b/client/test/test_tcp.s
@@ -6,6 +6,12 @@
   
   .import parse_dotted_quad
   .import dotted_quad_value
+  
+  .import tcp_listen
+  .import tcp_callback
+  .import ip65_process
+  .import tcp_connect
+  .import tcp_remote_ip
   
   .import  __CODE_LOAD__
   .import  __CODE_SIZE__
@@ -105,9 +111,29 @@ init:
   ldax  #$1234
   jsr test_add_16_32
 
+    
+  jsr print_cr
+  init_ip_via_dhcp 
+  jsr print_ip_config
+
+@loop_forever:
+  ldax  #tcp_callback_routine
+  stax  tcp_callback
+  ldax  tcp_dest_ip
+  stax  tcp_remote_ip
+  ldax  tcp_dest_ip+2
+  stax  tcp_remote_ip+2
+  
+  
+  ldax  #80
+  jsr tcp_connect
+
+  jsr ip65_process
+  jmp @loop_forever
   rts
 
-
+tcp_callback_routine:
+  rts
 
 
 ;assumes acc32 & op32 already set
@@ -226,3 +252,6 @@ number15:
 
 number16:
   .byte $00,$00,$00,$00
+
+tcp_dest_ip:
+  .byte 10,5,1,1
\ No newline at end of file