FTS-0006










                            YOOHOO and YOOHOO/2U2

                    The netmail handshake used by Opus-CBCS
             and other intelligent Fidonet mail handling packages


                This document obsoletes and replaces FTS-0003










LEGAL STUFF
-----------

The original  protocol and documentation are by Wynn Wagner III.  Updates
have been made  to  this  document  by Vincent E.  Perriello, who also is
responsible for most of the sample routine included with this document.

They are released to  the public domain for any use whatsoever as long as
you don't modify any transmitted  structure  or try to make money hawking
either the sample code or this document as if you owned them.

If you choose to use the  method  or  the  sample  routines,  you  do  so
entirely at your own risk.  It  is  possible that the routines will cause
physical damage to your equipment, an invasion of  fire ants, the plague,
or an extended visit from in-laws.  If any  of  that  stuff  (or anything
else) happens, you accept the consequences totally.


CREDITS
-------

Fido  and  Fidonet  are  registered  trademarks of Tom Jennings and  Fido
Software.

SEAdog is a product of System Enhancement Associates.

The ZModem protocol was designed by Chuck Forsberg.  The Sealink protocol
is copyrighted  by System Enhancment Associates.  The TeLink protocol was
designed and first implemented by Tom Jennings.

The state charts in this document were done by Vince Perriello.

Rick Huebner designed  and  implemented  the  basic  WaZOO  file  request
method.  Update request functionality was added by Vince Perriello.

YooHoo and YooHoo/2u2                                              Page 2
Overview



UPFRONT
-------

YOOHOO and YOOHOO/2U2 are  the  initial  handshakes  for the WaZOO e-mail
protocol.  They are designed to let two systems establish a common ground
for a netmail session while making  sure  that non-WaZOO software doesn't
get upset by material it can't understand.

The YOOHOO procedure begins as a single  byte  (0xf1).   If the system on
the other end doesn't reply to that byte,  no  further  YOOHOO  or  WaZOO
transmissions are attempted.  To a non-WaZOO netmail system,  the  YOOHOO
byte will simply seem like a byte of debris.

The  calling  system  initiates  the  YOOHOO  by  sending  the  attention
character.   If the receiving system seems interested, the calling system
sends a  128  byte packet containing such information as system and sysop
names as well as a "capability mask." A 16-bit CRC protects the integrity
of the 128-byte packet.

In response, the receiving  system  prepares  a  128  byte packet to send
back.  This is the YOOHOO/2U2 procedure.



FEATURES
--------

The features of YOOHOO and YOOHOO/2U2 include

         * non-interference with systems that don't understand the
           handshake

         * almost foolproof method for identifying a remote system
           and establishing a common ground for transmission

         * built-in room to expand the capabilities of WaZOO without
           having to resort to a kludge



USAGE
-----

A calling system simply uses  a  routine  that  transmits both YooHoo and
TSYNC  handshake initiating characters to the  called  system.    If  the
called system responds with an XMODEM 'NAK',  an FTS-0001 session will be
initiated.  If an 'ENQ' is received, the  `YooHoo_Sender()'  routine will
be invoked to handle the session negotiation.

A  receiving  system  can call a routine like `YooHoo_Receiver()'  if  it
detects the YOOHOO character, or just drop into the FTS-0001  logic if it
sees a TSYNC.

This simple method allows a mailer to take care of both the TSYNC and the
YOOHOO handshakes.

YooHoo and YooHoo/2u2                                              Page 3
WaZOO Protocols



PROTOCOLS
---------

Currently there are two WaZOO methods in use:

         DietIFNA ... similar to the method described by the FidoNet
                      Technical Standards Committee.

                      VARIATION:  * file attaches don't even attempt to
                                    do a modem7 file name.

                                  * SEAlink run-ahead is based on the
                                    baud rate and can be as high as 24
                                    packets for 9600 baud.

                                  * If the calling system transmits a
                                    .REQ file for file requests, the
                                    receiving system can respond to it.
                                    See "WaZOO File Requests" (below)
                                    for information on the .REQ file.

                                  * When there is nothing to send, a
                                    system should remain quiet.  In
                                    other words, the end of a session
                                    can be determined by a timeout.

                                  * Under no circumstances should "BARK"
                                    file request logic be activated
                                    during a DietIFNA session. File
                                    requests, if any, should be
                                    transmitted using a .REQ file.

         ZedZap ..... a zmodem variant. The originator does a batch send
                      then goes into a receive batch mode.  The called
                      system does receive then send. In the event of a
                      file request (see description below) made by the
                      called system, one more turnaround is made to
                      service the request.

                      VARIATION:  * Unlike the true zmodem protocol
                                    described by Chuck Forsberg, ZedZap
                                    routines must be able to handle a
                                    batch mode that has no actual files.
                                    In other words, it is possible for
                                    there to be a init sequence
                                    followed immediately by a ZFIN.

                                  * The maximum packet size is based on
                                    the baud rate.  For example, at 2400
                                    baud it's 2048 bytes.  At 9600 baud,
                                    the packets are 8192 bytes. THIS IS
                                    A SIGNIFICANT VARIATION FROM STRICT
                                    ZMODEM IMPLEMENTATION. (There's
                                    another YooHoo capability bit for
                                    those systems which cannot handle
                                    this block size)

YooHoo and YooHoo/2u2                                              Page 4
WaZOO Filename conventions



WaZOO FILENAMES
---------------


         MESSAGE BUNDLES...xxxxxxxx.PKT

                           Normal (unarchived) messages are sent in a file
                           name that has a tag of .PKT.  The "x" characters
                           should be hex digits.

                           IMPLEMENTATION NOTE
                           -------------------
                           There is no real requirement that a .PKT file be
                           part of a netmail session.  Opus 1.03 and below
                           require a .PKT file for DietIFNA, but this is
                           a mistake that will be corrected.  The correct
                           way to do things is to send only what needs to
                           be sent.  If the calling system is doing a "poll"
                           then only the YooHoo and a SEAlink (or TeLink)
                           end-of-batch sequence should be all that is
                           required.


         LZ BUNDLES........xxxxxxxx.{MO|TU|WE|TH|FR|SA|SU}#

                           Message bundles are often shipped in an archive
                           that has been compressed with some LZ utility.

                           The file name consists of a name with hex digits.
                           The tag  is  one  of  seven  two-character
                           prefixes ("MO","TU","WE","TH","FR","SA" or "SU")
                           and a number (0-9).


         FILE REQUESTS.....xxxxxxxx.REQ

                           This is explained below.

                           In a nutshell, the file name consists of the
                           receiving system's Fidonet address expressed
                           as two 4-digit hex numbers.  The file tag is .REQ.

YooHoo and YooHoo/2u2                                              Page 5
Flow of a DietIFNA Session



DIETIFNA FLOW AND NOTES
-----------------------

         All file transfer is done using either Sealink or TeLink. In the
         case of TeLink, the modem7 file name transfer part is not used,
         and the file name is extracted from the first block.

         The sealink run-ahead (number of blocks in the slide) is based
         on the baud rate:  BlocksToSlide = BaudRate / 400, up to a max
         of 24 blocks.



         The calling system:

                  * Send YooHoo

                  * Receive YooHoo/2u2

                  * Send bundles, files, file request (.REQ) files
                    (in that order)

                  * Receive bundles, files, requested files (in that order)


         Receiving system:

                  * Receive YooHoo

                  * Send YooHoo/2u2

                  * Receive bundles, files, file requests (in that order)

                  * Send bundles, files, and respond to file requests that
                    arrived from the remote system.

YooHoo and YooHoo/2u2                                              Page 6
Flow of a ZedZap session



ZEDZAP FLOW
-----------

         The calling system:

                  * Send YooHoo

                  * Receive YooHoo/2u2

                  * Send bundles, files, file request (.REQ) files
                    (in that order)

                  * Receive bundles, files, file requests

                  * If a file request (.REQ) file came in,
                    respond to it


         Receiving system:

                  * Receive YooHoo

                  * Send YooHoo/2u2

                  * Receive bundles, files, file requests

                  * Send bundles, files, our file requests, and
                    respond to file requests that arrived from the
                    remote system.

                  * If we sent a .REQ file in the preceding step,
                    wait for the other system to respond.

YooHoo and YooHoo/2u2                                              Page 7
WaZOO File Requests



WAZOO FILE REQUESTS
-------------------

Rick Huebner, who adapted the ZModem routines for Opus, designed the
.REQ file-based file request system.


REQ FILE:

A WaZOO file request is based on a request file.  The name of a request
file is similar to the .OUT and .FLO files used by Opus-CBCS.

         TEMPLATE: netnode.REQ

         EXAMPLE:  00010002.REQ   ... a request being sent to 1/2

The .REQ file is simply a text file that contains the files we want from
the remote system.  Those file names can include wildcards, but should
not contain a path.  Optionally, there can be a password... if the sending
system requires one.

The "netnode" part of the file name is built from the remote systems net
and node numbers.  Both numbers become 4-character hex numbers in the
file name.

Let's say we're requesting THIS.ARC and all node lists from 12/2.  The
file name would be 000C0002.REQ.  The contents would look like this:

                  this.arc
                  nodelist.*

If the sysop of 12/2 requires a password of THAT to get the file THIS.ARC,
the REQ file contents would have to change:

                  this.arc !that
                  nodelist.*

Transaction-level passwords (of 6 or fewer characters) follow the file name:

                  <filename><single-space-character>!<password><cr>

YooHoo and YooHoo/2u2                                              Page 8
WaZOO File Requests




If the request is of the "update" genre, the type of update and the time,
expressed as a UNIX-style long decimal ASCII number, follows the name, or
in the event that there is a transaction-level password, the password. For
example, an update request for file NEWOPUS.*, where you already have a file
dated 1-January 1989, 00:00 and you live on the East Coast (GMT+06) would be:

                  NEWOPUS.* +599634000

The sign is required, it indicates the type of update request. A '+' means
that all files matching the filespec "NEWOPUS.*" newer than the shown time
will be sent, a '-' means that all matching files with dates up to and
including the indicated time will be sent.


The complete format of an action line in an REQ file is, then:

          <filename>[<space>!<password>][<space><+/-><time>]<cr>



MECHANISM:

During the WaZOO session, the .REQ file is simply transmitted to the
other system.  It goes "as is" like any other file.

The other system can ignore the request, send some of the files, or send
all of the files.  There is no accounting or responsibilities on the
part of the remote system.

If your implementation is unable to process the update information for any
reason, then you should process the line as a "regular" file request.



NOTE:

In the YooHoo packet, there's a bit that lets you know if the remote
system currently accepts .REQ files.  This will be a clue as to whether
a .REQ file would be a waste of time or not. Procedurally it's probably
best to not send a .REQ file to a system which indicates that it won't
process it.

YooHoo and YooHoo/2u2                                              Page 9
Structures and Definitions



STRUCTURES AND DECLARATIONS
---------------------------


#define ACK    0x06
#define NAK    0x15
#define ENQ    0x05
#define YOOHOO 0xf1
#define TSYNC  0xae

struct   _Hello
    {
    word     signal;           /* always 'o'     (0x6f)                   */
    word     hello_version;    /* currently 1    (0x01)                   */
    word     product;          /* product code                            */
    word     product_maj;      /* major revision of the product           */
    word     product_min;      /* minor revision of the product           */
    char     my_name[60];      /* Other end's name                        */
    char     sysop[20];        /* sysop's name                            */
    word     my_zone;          /* 0== not supported                       */
    word     my_net;           /* out primary net number                  */
    word     my_node;          /* our primary node number                 */
    word     my_point;         /* 0== not supported                       */
    byte     my_password[8];   /* This is not necessarily null-terminated */
    byte     reserved2[8];     /* reserved by Opus                        */
    word     capabilities;     /* see below                               */
    byte     reserved3[12];    /* for non-Opus systems with "approval"    */
    };                         /*          total size 128 bytes           */



/*------------------------------------------------------------------------*/
/* YOOHOO<tm> CAPABILITY VALUES                                           */
/*------------------------------------------------------------------------*/
#define Y_DIETIFNA 0x0001  /* Can do fast "FTS-0001"  0000 0000 0000 0001 */
#define FTB_USER   0x0002  /* Full-Tilt Boogie        0000 0000 0000 0010 */
#define ZED_ZIPPER 0x0004  /* Does ZModem, 1K blocks  0000 0000 0000 0100 */
#define ZED_ZAPPER 0x0008  /* Can do ZModem variant   0000 0000 0000 1000 */
#define DOES_IANUS 0x0010  /* Can do Janus            0000 0000 0001 0000 */
#define Bit_5      0x0020  /* reserved by FTSC        0000 0000 0010 0000 */
#define Bit_6      0x0040  /* reserved by FTSC        0000 0000 0100 0000 */
#define Bit_7      0x0080  /* reserved by FTSC        0000 0000 1000 0000 */
#define Bit_8      0x0100  /* reserved by FTSC        0000 0001 0000 0000 */
#define Bit_9      0x0200  /* reserved by FTSC        0000 0010 0000 0000 */
#define Bit_a      0x0400  /* reserved by FTSC        0000 0100 0000 0000 */
#define Bit_b      0x0800  /* reserved by FTSC        0000 1000 0000 0000 */
#define Bit_c      0x1000  /* reserved by FTSC        0001 0000 0000 0000 */
#define Bit_d      0x2000  /* reserved by FTSC        0010 0000 0000 0000 */
#define Bit_e      0x4000  /* reserved by FTSC        0100 0000 0000 0000 */
#define WZ_FREQ    0x8000  /* WZ file req. ok         1000 0000 0000 0000 */

YooHoo and YooHoo/2u2                                              Page 10
State Tables



 +--------------------------------------------------------------------------+
 |                                                                          |
 |  YOOHOO<tm>: SENDER (CALLING System)                                     |
 |                                                                          |
 |  ##   Status/Action  Stimulus            Action (comment)       Goto     |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s1 | Set 30.second |                   |                     |  s2      |
 |     | failsafe      |                   |                     |          |
 |     | timer         |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s2 | Send YOOHOO   |                   |                     |  s3      |
 |     | character     |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s3 | Send TSYNC    |                   |                     |  s4      |
 |     | character     |                   |                     |          |
 |     | (SEE NOTE #1) |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s4 | Read char     | Nothing in 3 sec  | report not a WaZOO  | return   |
 |     |               | or lost carrier   |                     |          |
 |     |               | or timer elapsed  |                     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received ENQuire  | send handshake      |  s8      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 'C'      | Other end may be    |  s5      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received NAK      | Could be a FTS-0001 |  s6      |
 |     |               |                   | mailer responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 01 Hex   | Other end may be    |  s7      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | try again           |  s4      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s5 | Read char     | Nothing in 3 sec  | Pretend other side  | return   |
 |     |               |                   | is FTS-0001 mailer  |          |
 |     |               |                   | responding to TSYNC |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Timer elapsed     | report not a WaZOO  | return   |
 |     |               | or Carrier lost   |                     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received ENQuire  | send handshake      |  s8      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received NAK      | Could be a FTS-0001 |  s6      |
 |     |               |                   | mailer responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 01 Hex   | Other end IS a      | return   |
 |     |               | Received 00 Hex   | SEAdog responding   |          |
 |     |               | Received 'C'      | to the TSYNC        |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | try again           |  s4      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s6 | Read char     | Nothing in 3 sec  | report not a WaZOO  | return   |
 |     |               | or lost carrier   |                     |          |
 |     |               | or timer elapsed  |                     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received ENQuire  | send handshake      |  s8      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 'C'      | Other end may be    |  s5      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received NAK      | It IS a FTS-0001    | return   |
 |     |               |                   | mailer responding   |          |
 |     |               |                   | to the TSYNC        |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 01 Hex   | Other end may be    |  s7      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | try again           |  s4      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s7 | Read char     | Nothing in 3 sec  | report not a WaZOO  | return   |
 |     |               | or lost carrier   |                     |          |
 |     |               | or timer elapsed  |                     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received ENQuire  | send handshake      |  s8      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 'C'      | Other end may be    |  s5      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received NAK      | Might be a FTS-0001 |  s6      |
 |     |               |                   | mailer responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received 01 Hex   | Other end may be    |  s7      |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC.  Need |          |
 |     |               |                   | further checking.   |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received FE Hex   | Other end IS a      | return   |
 |     |               |                   | SEAdog responding   |          |
 |     |               |                   | to the TSYNC        |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | try again           |  s4      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s8 | Send HELLO    | Successful        | Looks like WaZOO    |  s9      |
 |     | (see hello    |                   |                     |          |
 |     |     chart)    +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Not successful    | Repeat whole thing  |  s2      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  s9 | Read char     | Nothing in 5 sec  | repeat whole thing  |  s2      |
 |     |               | or lost carrier   |                     |          |
 |     |               | or timer elapsed  |                     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received YOOHOO   | Another WaZOO, go   |  s10     |
 |     |               |                   | process receive     |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | Repeat whole thing  |  s2      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 | s10 | Process other | Information       | Report Success      |  return  |
 |     | side's YOOHOO | Successfully      |                     |          |
 |     | (See "Receive | Exchanged         |                     |          |
 |     | Hello Packet" |                   |                     |          |
 |     | chart)        +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Failure           | Repeat whole thing  |  s2      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 +--------------------------------------------------------------------------+


         NOTE #1. Sending the TSYNC character is needed only if you
                  are also supporting the FTS-0001 method.  TSYNC is
                  not part of YooHoo/WaZOO.


 +--------------------------------------------------------------------------+
 |                                                                          |
 |  YOOHOO: RECEIVER   (CALLED system)                                      |
 |                                                                          |
 |                                                                          |
 |  ##   Status/Action  Stimulus            Action (comment)       Goto     |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v1 | Got YOOHOO    |                   | Smells interesting  |  v3      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v2 | Got TSYNC     |                   | Report FTS-0001     | return   |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v3 | Get HELLO     | Successful        | Let's send ours now |  v4      |
 |     | packet from   |                   |                     |          |
 |     | remote (see   +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     | "Receive Hello|                   |                     |          |
 |     | packet")      | Not successful    | Report failure      | return   |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v4 | Look for ENQ  | Timer elapsed?    | 10 sec. timeout     |  v5      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Character not ENQ | Debris              |  v4      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | ENQ received      | Transmit Hello      |  v6      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v5 | Clear inbound | Count expired?    | 5 retrys, failed.   |  return  |
 |     | Send YOOHOO   |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Count not expired | Try again           |  v4      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  v6 | Send HELLO    | Successful        | Success             |  return  |
 |     | (see "Send    |                   |                     |          |
 |     | Hello" chart) +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Not successful    | Repeat whole thing  |  v1      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 +--------------------------------------------------------------------------+




 +--------------------------------------------------------------------------+
 |                                                                          |
 | SEND HELLO PACKET                                                        |
 |                                                                          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  h1 | Disable XON   |                   |                     |  h2      |
 |     | Disable ^C/^K |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  h2 | Send Header   | Transmit the 128  |                     |  h3      |
 |     |               | byte HELLO struct |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  h3 | Clear inbound |                   |                     |  h4      |
 |     | buffer        |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  h4 | Send CRC      | Transmit the 16   |                     |  h5      |
 |     |               | bit CRC of HELLO  |                     |          |
 |     |               | as two bytes, MSB |                     |          |
 |     |               | followed by LSB   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  h5 | Read char     | Received ACK      | Success             |  return  |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received '?'      | Try header again    |  h2      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received ENQ      | Might be out of sync|  h5      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Received debris   | Might be line noise |  h5      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Time out          | Failure             |  return  |
 |     |               | (30 sec timer)    |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 +--------------------------------------------------------------------------+



 +--------------------------------------------------------------------------+
 |                                                                          |
 |  RECEIVE HELLO PACKET                                                    |
 |                                                                          |
 |                                                                          |
 |  ##   Status/Action  Stimulus            Action (comment)       Goto     |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r1 | Clear buffers |                   |                     |  r2      |
 |     | Disable XON   |                   |                     |          |
 |     | Disable ^C/^K |                   |                     |          |
 |     | Set timer     |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r2 | Send ENQuire  |                   | Let other end know  |  r3      |
 |     |               |                   | we heard YOOHOO.    |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r3 | Watch for Hex | Timeout           | 10 sec. elapsed.    |  r4      |
 |     | 1f (Header)   |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Carrier loss      | Report failure      | return   |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Got header char   | Get Hello string    |  r5      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Got a YooHoo      | Resync - send ENQ   |  r2      |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Character not     | Keep watching       |  r3      |
 |     |               | header (0x1f)     |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r4 | Bump          | Count expired?    | No YooHoo, 10 retrys| return   |
 |     | Retry         |                   |                     |          |
 |     | Count         +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Still a few turns | Try again           |  r2      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r5 | Receive 128   | Nothing for 30sec | Report failure      | return   |
 |     | bytes (hello) |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Got all 128 bytes |                     |  r6      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r6 | Get CRC       | One or both CRC   | Short packet        |  r7      |
 |     | (two bytes,   | characters timed  |                     |          |
 |     | MSB followed  | out (over 10 sec) |                     |          |
 |     | by LSB)       |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Error             | CRC isn't what it   |  r7      |
 |     |               |                   | should be           |          |
 |     |               |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | CRC compares      | Successful transfer |  r8      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 |  r7 | Error handler | Count expired?    | 10 failures to get  | return   |
 |     | Send '?'      |                   | hello. Hang up.     |          |
 |     | (0x3f)        |                   |                     |          |
 |     |               +- - - - - - - - - -+- - - - - - - - - - -+- - - - - |
 |     |               |                   |                     |          |
 |     |               | Count not expired | Try again           |  r3      |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 |     |               |                   |                     |          |
 | r8  | Clear inbound |                   | Report success      | return   |
 |     | Send ACK      |                   |                     |          |
 |     | Send YOOHOO   |                   |                     |          |
 |     |               |                   |                     |          |
 | ----+---------------+-------------------+---------------------+--------- |
 +--------------------------------------------------------------------------+





                                      ###

