diff --git a/client/inc/common.i b/client/inc/common.i
index 56c7202..277887a 100644
--- a/client/inc/common.i
+++ b/client/inc/common.i
@@ -15,3 +15,15 @@
 	stx 1+(arg)
 	.endmacro	
 
+
+.macro phax
+  pha
+  txa
+  pha
+.endmacro
+
+.macro plax
+  pla
+  tax
+  pla
+.endmacro
\ No newline at end of file
diff --git a/client/inc/nb65_constants.i b/client/inc/nb65_constants.i
index 1e813e6..a4e3434 100644
--- a/client/inc/nb65_constants.i
+++ b/client/inc/nb65_constants.i
@@ -35,7 +35,8 @@ NB65_TFTP_DIRECTORY_LISTING    EQU $20 ;inputs: AX points to a TFTP parameter st
 NB65_TFTP_DOWNLOAD             EQU $21 ;inputs: AX points to a TFTP parameter structure, outputs: TFTP param structure updated with 
                                        ;NB65_TFTP_POINTER updated to reflect actual load address (if load address $0000 originally passed in)
 NB65_TFTP_CALLBACK_DOWNLOAD    EQU $22 ;inputs: AX points to a TFTP parameter structure, outputs: none
-NB65_TFTP_CALLBACK_UPLOAD      EQU $23 ;upload: AX points to a TFTP parameter structure, outputs: none
+NB65_TFTP_UPLOAD               EQU $23 ;upload: AX points to a TFTP parameter structure, outputs: none
+NB65_TFTP_CALLBACK_UPLOAD      EQU $24 ;upload: AX points to a TFTP parameter structure, outputs: none
 
 NB65_DNS_RESOLVE               EQU $30 ;inputs: AX points to a DNS parameter structure, outputs: DNS param structure updated with 
                                    ;NB65_DNS_HOSTNAME_IP updated with IP address corresponding to hostname.
@@ -63,6 +64,7 @@ NB65_DRIVER_NAME     EQU $1A     ;2 byte pointer to name of driver
 NB65_TFTP_IP         EQU $00                     ;4 byte IP address of TFTP server
 NB65_TFTP_FILENAME   EQU $04                     ;2 byte pointer to asciiz filename (or filemask in case of NB65_TFTP_DIRECTORY_LISTING)
 NB65_TFTP_POINTER    EQU $06                     ;2 byte pointer to memory location data to be stored in OR address of callback function
+NB65_TFTP_FILESIZE   EQU $08                     ;2 byte file length (filled in by NB65_TFTP_DOWNLOAD, must be passed in to NB65_TFTP_UPLOAD)
 
 ;offsets in DNS parameter structure (used by NB65_DNS_RESOLVE)
 NB65_DNS_HOSTNAME    EQU $00                         ;2 byte pointer to asciiz hostname to resolve (can also be a dotted quad string)
diff --git a/client/ip65/function_dispatcher.s b/client/ip65/function_dispatcher.s
index 9fc1df4..22a2a36 100644
--- a/client/ip65/function_dispatcher.s
+++ b/client/ip65/function_dispatcher.s
@@ -23,6 +23,7 @@
 .import tftp_download
 .import tftp_upload
 .import tftp_set_callback_vector
+.import tftp_filesize
 .import dns_ip
 .import dns_resolve
 .import dns_set_hostname
@@ -46,7 +47,7 @@ nb65_params = copy_src
 
 .data
 
-old_ax: .res 2
+
 jmp_old_irq:
   jmp $0000
 
@@ -102,7 +103,6 @@ set_tftp_callback_vector:
   
 nb65_dispatcher:
   stax nb65_params
-  stax old_ax
   
 
   cpy #NB65_INITIALIZE
@@ -132,37 +132,6 @@ irq_handler_installed:
 :
 
 
-
-  cpy #NB65_TFTP_DIRECTORY_LISTING  
-  bne :+
-  jsr set_tftp_params
-  jsr tftp_directory_listing
-
-@after_tftp_call:  ;write the current load address back to the param buffer (so if $0000 was passed in, the caller can find out the actual value used)
-  bcs @tftp_error
-  ldax old_ax
-  stax nb65_params
-
-  ldy #NB65_TFTP_POINTER
-  lda tftp_load_address
-  sta (nb65_params),y  
-  iny
-  lda tftp_load_address+1
-  sta (nb65_params),y
-  
-  clc
-@tftp_error:
-@dns_error:   
-  rts
-:
-
-  cpy #NB65_TFTP_DOWNLOAD
-  bne :+
-  jsr set_tftp_params
-  jsr tftp_download
-  jmp @after_tftp_call
-:
-
   cpy #NB65_DNS_RESOLVE
   bne :+  
   ldy #NB65_DNS_HOSTNAME+1
@@ -171,7 +140,7 @@ irq_handler_installed:
   dey
   lda (nb65_params),y
   jsr dns_set_hostname  
-  bcs @dns_error
+  bcc @dns_error
   jsr dns_resolve
   bcs @dns_error
   ldy #NB65_DNS_HOSTNAME_IP
@@ -182,7 +151,9 @@ irq_handler_installed:
   iny
   dex  
   bne @copy_dns_ip
+@dns_error:
   rts
+    
 :
 
   cpy #NB65_UDP_ADD_LISTENER
@@ -299,11 +270,52 @@ irq_handler_installed:
   rts
 :  
 
+
+  cpy #NB65_TFTP_DIRECTORY_LISTING  
+  bne :+
+  phax
+  jsr set_tftp_params
+  jsr tftp_directory_listing
+
+@after_tftp_call:  ;write the current load address back to the param buffer (so if $0000 was passed in, the caller can find out the actual value used)
+  plax
+  bcs @tftp_error
+  stax nb65_params
+
+  ldy #NB65_TFTP_POINTER
+  lda tftp_load_address
+  sta (nb65_params),y  
+  iny
+  lda tftp_load_address+1
+  sta (nb65_params),y
+
+  ldy #NB65_TFTP_FILESIZE
+  lda tftp_filesize
+  sta (nb65_params),y  
+  iny
+  lda tftp_filesize+1
+  sta (nb65_params),y
+  clc
+@tftp_error:   
+  rts
+:
+
+  cpy #NB65_TFTP_DOWNLOAD
+  bne :+
+  phax
+  jsr set_tftp_params
+  jsr tftp_download
+  jmp @after_tftp_call
+:
+
+
   cpy #NB65_TFTP_CALLBACK_DOWNLOAD
   bne :+
+  phax
   jsr set_tftp_params
   jsr set_tftp_callback_vector
-  jmp tftp_download
+  jsr tftp_download
+  jmp @after_tftp_call
 :
 
   cpy #NB65_TFTP_CALLBACK_UPLOAD
diff --git a/client/ip65/tftp.s b/client/ip65/tftp.s
index 7ae357e..b8af3b3 100644
--- a/client/ip65/tftp.s
+++ b/client/ip65/tftp.s
@@ -21,6 +21,7 @@
   .export tftp_set_callback_vector
   .export tftp_data_block_length
   .export tftp_clear_callbacks
+  .export tftp_filesize
   
 	.import ip65_process
   .import ip65_error
@@ -91,15 +92,16 @@ tftp_actual_server_ip: .res 4     ;this is read from the reply - it may not be t
 tftp_just_set_new_load_address: .res 1
 
 tftp_opcode: .res 2 ; will be set to 4 if we are doing a RRQ, or 7 if we are doing a DIR
+tftp_filesize: .res 2 ;will be set by tftp_download, needs to be set before calling tftp_upload_from_memory
 
 .code
 
-;uploads a file to a tftp server
+;uploads a file to a tftp server with data retrieved from specified memory location
 ; inputs:
-;   tftp_ip: ip address of host to download from (set to 255.255.255.255 for broadcast)
-;   tftp_filename: pointer to null terminated name of file to download
-;     of file should be loaded into (e.g. if downloading a C64 'prg' file)
-;    a callback vector should have been set with tftp_set_callback_vector
+;  tftp_ip: ip address of host to send file to (set to 255.255.255.255 for broadcast)
+;  tftp_filename: pointer to null terminated name of file to upload
+;  tftp_load_address: starting address of data to be sent
+;  tftp_filesize: length of data to send
 ; outputs: carry flag is set if there was an error
 ;   if a callback vector has been set with tftp_set_callback_vector
 ;   then the specified routine will be called once for each 512 byte packet
@@ -109,6 +111,18 @@ tftp_opcode: .res 2 ; will be set to 4 if we are doing a RRQ, or 7 if we are doi
 ;   with file downloaded.
 ;   tftp_load_address: will be set to the actual address loaded into (NB - this field is
 ;       ignored if a callback vector has been set with tftp_set_callback_vector)
+tftp_upload_from_memory:
+  ldax #copy_ram_to_tftp_block
+  jsr tftp_set_callback_vector
+  
+;uploads a file to a tftp server with data retrieved from user supplied routine
+; inputs:
+;  tftp_ip: ip address of host to send file to (set to 255.255.255.255 for broadcast)
+;  tftp_filename: pointer to null terminated name of file to upload
+;   a callback vector should have been set with tftp_set_callback_vector
+; outputs: carry flag is set if there was an error
+;   the specified routine will be called once for each 512 byte packet
+;   to be sent from the tftp server.
 tftp_upload:
   ldax  #$0200      ;opcode 02 = WRQ
   jmp set_tftp_opcode
@@ -153,7 +167,10 @@ tftp_directory_listing:
 ;   tftp_load_address: will be set to the actual address loaded into (NB - this field is
 ;       ignored if a callback vector has been set with tftp_set_callback_vector)
 tftp_download:
-  ldax  #$0100      ;opcode 01 = RRQ
+  lda #00
+  sta tftp_filesize
+  sta tftp_filesize+1
+  ldx #$01                      ;opcode 01 = RRQ (A should already be zero from having just reset file length)
 set_tftp_opcode:  
   stax  tftp_opcode
   lda #tftp_initializing
@@ -503,6 +520,10 @@ copy_tftp_block_to_ram:
   sta tftp_current_memloc+1
   rts
 
+;default handler for uploading a file
+copy_ram_to_tftp_block:
+  rts
+
 ;set up vector of routine to be called when each 512 packet arrives from tftp server 
 ;when downloading OR for routine to be called when ready to send new block
 ;when uploading.
diff --git a/client/test/test_cart_api.s b/client/test/test_cart_api.s
index 29c42e1..cf8f1cb 100644
--- a/client/test/test_cart_api.s
+++ b/client/test/test_cart_api.s
@@ -174,8 +174,15 @@ init:
   stax nb65_param_buffer+NB65_TFTP_POINTER
   ldax #nb65_param_buffer
   call #NB65_TFTP_CALLBACK_DOWNLOAD
-
-
+  lda #'$'
+  jsr print_a
+  lda  nb65_param_buffer+NB65_TFTP_FILESIZE+1
+  jsr print_hex
+  lda  nb65_param_buffer+NB65_TFTP_FILESIZE
+  jsr print_hex
+  print #bytes_download
+  print_cr
+  
 ;udp callback test
   
   ldax  #64     ;listen on port 64
@@ -409,6 +416,8 @@ ok:
 dns_lookup_failed_msg:
  .byte "DNS LOOKUP FAILED", 0
 
+bytes_download: .byte "BYTES DOWNLOADED",13,0
+
 reply_message:
   .byte "PONG!"
 reply_message_end:
diff --git a/doc/nb65_api_technical_reference.doc b/doc/nb65_api_technical_reference.doc
index d8a9266..69e4182 100644
Binary files a/doc/nb65_api_technical_reference.doc and b/doc/nb65_api_technical_reference.doc differ