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          CompuServe VIDTEX

      Error Free File Transfers


You can transfer files directly
between your system and CompuServe
using "B" Protocol transfer.

"B" Protocol ensures the accuracy of
the transmitted file.  Any errors are
detected and corrected.  Thus your
important files are protected against
possible damage from telephone line
noise and other types of interference.




   How To Use "B" Protocol Transfer
--------------------------------------

The procedure to perform a file
transfer on CompuServe is described
below.  A few terms must first be
defined in order to explain file
transfers:

     DOWNLOAD means to transfer a file
     from CompuServe to your computer.

     UPLOAD means to transfer a file
     from your computer to CompuServe.

     HOST refers to CompuServe's
     computers.

     REMOTE refers to your computer.

Three types of file tranfers may be
performed:

     TEXT
     MACHINE SPECIFIC
     BINARY

For both an upload and a download, the
CompuServe file extension determines
the type of transfer performed.  The
valid extensions and transfer types
are:

     .TXT  Text transfer
     .IMG  Machine specific transfer
     .BIN  Binary transfer

If any other or no extension is used,
a TEXT transfer is performed.

A TEXT transfer is used to transfer
ASCII text files such as untokenized
BASIC programs and text files.  When
uploading a text file, VIDTEX
translates from the remote computer's
character representation to standard
ASCII.  This usually includes adding
line feeds to carriage returns.  When
a text file is downloaded, VIDTEX
translates the text from standard
ASCII to the microcomputer's character
representation.

A MACHINE SPECIFIC transfer is used to
transfer machine dependent files.
This method is preferred over binary
transfer since it transfers files
specific to the Commodore 64.

During a machine specific transfer,
VIDTEX inserts all of the information
it needs to recreate the file exactly
as it originally existed.  If an
attempt is made to download a machine
specific file to a microcomputer which
is of a different type from the
microcomputer from which the file was
uploaded, VIDTEX will issue a warning
message.  Machine specific transfers
can be used to transfer files that
have information kept outside of the
file (usually in the disk directory)
that is essential to the file.  This
type of transfer supports Commodore
program (PGM) and sequential (SEQ)
files.

A BINARY transfer is used to transfer
eight bit files such as tokenized
BASIC programs and machine language
programs.  This can also be used to
transfer most microcomputer's BASIC
data files.  VIDTEX does not alter any
data during a binary file transfer.
Machine specific information is not
included in a binary transfer.


One way to initiate a file transfer is
to enter at the CompuServe Programming
Area (OK) prompt:

R FILTRN

CompuServe then responds:

CompuServe File Transfer Program

Your machine then is interrogated to
see if you are running a version of
VIDTEX which supports file transfers.
If you are not running a VIDTEX
program or if your version of VIDTEX
does not support file transfers, an
error message is printed and you are
returned to the 'OK' prompt.  If you
are running a version of VIDTEX which
supports file transfer, you are asked
for the direction of the transfer:

Select direction-
     D if to your computer
     U if to CompuServe
:

Enter a U to upload or D to download.
You then are prompted:

Enter the CompuServe file name:

Enter an appropriate file name and
extension.  Remember that the file
extension determines the type of
transfer performed.  For a download
this is the name of the existing file
to be transfered to your
microcomputer.  For an upload this is
the name of the file to be created.
You then are prompted:

Enter a file name for your computer:

Enter the file specification as
required by your operating system.
You can specify any file following the
naming rules of your system.  This
might include a drive designation, a
file name extension, punctuation, or a
password.

When using machine specific transfer,
the file type is handled automatically
by VIDTEX.  However, when using binary
or text transfer, the default
Commodore file type is sequential
(SEQ).  To specify a program file
(PGM), append ",p" after the normal
file name.  For example, the file
"game" would be downloaded as a
sequential file, but "game,p" would be
downloaded as a program file.

Since the format for file names is
different for every microcomputer, no
syntax checking is performed on the
remote file name.  The remote file
name does not affect the type of
transfer performed.

VIDTEX will not overwrite an existing
file on a download;  you must first
delete the file yourself.

The file transfer then begins.  As the
transfer proceeds, a series of digits
are displayed on your screen.  Plus
signs (+) appear between the digits.

When the transfer is completed, the
message:

*** File Transfer Completed!  ***

appears and you are returned to the
'OK' prompt.

To abort a file transfer, hold META A
until the next digit appears on the
screen.




          SIG File Transfer
--------------------------------------

The DOW command is used to download a
file from a Special Interest Group
(SIG) database.  To initiate the
download of a file, "file.img" from
user number [73000,1] for instance,
enter at the SIG/Access prompt:

dow file.img[73000,1]

If you are running a program like
VIDTEX that supports "B" Protocol file
transfer, CompuServe then responds:

I need a file name for your computer:

You then enter the name that the file
is to be downloaded to.  Remember that
when using text (.TXT) or binary
(.BIN) files, you can force the file
type to be program by adding a ",p"
after the regular name for your
computer.

The file will be downloaded directly
to your disk.  While downloading
digits and plus signs will appear on
your screen to indicate the progress
of the download.  When the file is
created on your disk, VIDTEX will
display the name of the file being
downloaded on your screen.

After the download is complete, the
following prompt will appear:

SIG/Access:

If you attempt to download a machine
specific file (.IMG) that does not
contain the proper machine
identification information, VIDTEX
will issue the following:

This file may not be compatible with
your computer.
Do you want to receive it?

To continue the download type "Y" for
Yes or to stop type "N" for No.  If
you type "Y" then VIDTEX will download
the file as a sequential (SEQ) file
unless the file name for your computer
contains ",p" to force the file type
to be program.




 Services Using "B" Protocol Transfer
--------------------------------------

"B" Protocol transfer also is used in
many other CompuServe services that
require the accurate transfer of data.
These include:

   - MicroQuote (TM) is a series of
     programs for retrieving and
     storing current and historical
     stock data.  Over 40,000 issues
     are represented in the historical
     database which contains quotes
     back to January 1, 1974.

     The MicroQuote program, MQDATA,
     automatically stores stock
     information into a file which you
     can download using "B" Protocol.

   - SOFTEX (TM) is an on-line
     software shopping service.  You
     can purchase reasonably priced
     programs and download them
     directly to your computer for
     immediate use.  "B" protocol
     ensures the reliability of your
     purchase.

   - ACCESS (TM) is a database program
     used for facilitating the
     exchange of customer supplied
     software.

   - QTRAN (TM) is a program that will
     take a VisiCalc (R) file in DIF
     format and convert it into a
     batch input file for QUBIT (TM).
     QTRAN is available to commercial
     CompuServe customers only.


Use of "B" Protocol transfer in these
services is automated;  you do not
need to issue any special commands.
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