             YAKity YAK - Model 1/3/4 YMODEM Protocol.
                    Authored by Mike Bailey.
    YAKity YAK is based on Chuck Forsberg's Professional YAM.

This is version 1.1.2 of YAK.



YMODEM Protocol Overview

YMODEM is backwards compatable with the XMODEM CRC-16 file
transfer protocol.  It supports both 128 and 1,024 byte data
packets, CRC-16 error checking, and optional batch file
send/receive modes of operation.  Chuck Forsberg authored
the original Ymodem specifications of which this program is
based on.

In order to use this program to send or receive files using
YAK (Ymodem), type the following from DOS:

              YAK [ENTER] 

You will be presented with the YAK display screen. You will
have the following options available to you:

     <S>end, <R>eceive, <M>ulti-Send, <B>ulk-Receive

Send and Recieve will transfer the file according to the 
standard YMODEM single-file transfer.  You must input the
name of the file you wish to send or receive.


To invoke YMODEM Batch send or receive of files and data,
type the <M>ulti-Send or <B>ulk-Receive, respectively. You
will be presented with additional options:


<M>ulti-Send

Multi-Send will prompt you for up to 50 different filenames
that you wish to send.  Enter the filenames, pressing C/R
until you are completed.  Press C/R at the filename prompt
to exit the input routine and begin YMODEM batch-send.  YAK
will automatically open and send the files one at a time,
until all have been transferred.

Once this has been accomplished, YAK will notify you that it
has completed Batch-send, sound an alarm and will drop down
to DOS.


<B>ulk-Receive

Bulk-Receive is quick and easy to invoke.  From the YAK menu,
pressing B will select this option.  You will be prompted for
a drive number that you want all of the received files to be
placed on.  Enter any valid drive number.  The process is 
automated from this point on.  The YAK receiver obtains the 
filenames from the YMODEM Batch-sender and transfers one at a
time until all files have been received.  I think You'll enjoy
watching your computer download files completely unattended!
When all files have been transferred, YAK sounds an alarm and
drops back down to DOS.



Notes about the YAK Protocol

YAK always attempts to receive files using CRC-16 error
checking.  YAK will send using either CRC-16 or Checksum,
as requested by the receiver, in order to maintain backwards
compatability with other YMODEM or XMODEM protocols.  All
YMODEM implementations should support CRC-16.

YAK4/CMD will convert all PC/MSDOS Filenames/pathnames to
compatable Z-80 filenames/filespecs when receiving batch-files
and vice versa when sending files.  This ensures compatability
among all YMODEM drivers used today.



Notes about YMODEM and YAK YMODEM Extension

There are technically three protocols supported by YAK.
YMODEM, YMODEM Batch, and 1K XMODEM.  1K XMODEM is commonly
referred to as YMODEM, which is simply XMODEM with
optional 1,024 byte blocks rather than 128-byte blocks.

The two protocols ARE different, however when Chuck Forsberg
introduced his YMODEM (an XMODEM extension) it was a
1,024-byte block XMODEM CRC file transfer protocol. The name
has stuck ever since.

TRUE YMODEM (whether BATCH or single-file) always transfers
the first block as block zero.  However, I have yet to come
across a system that supports YMODEM-block zero protocol on
Single-File transfers. YMODEM is the same as 1K XMODEM in
almost all implementations that you'll find, including TBBS.

YAK does support the three protocols. Since true YMODEM and
1K XMODEM are identical except for the block zero, YAK will
adjusts itself according to the sender or receiver's needs,
just in case there are some systems out there that are using
true YMODEM block-zero (single-file) protocol.

YMODEM Batch, on the other hand, always transfers the first
block as block zero in all current implementations. 

Model 1/3/4 adaptations to Ymodem Batch were written
by Mike Bailey.  All technical questions should be addressed
to me through BBS @ (619) 571-6366.  Please note that I am
not the SYSOP of this board so please do not leave logoff
mail to me.

                  ' End Documentation
