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VIDTEX.HLP
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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. For example, when downloading the file from DL 12 named
CAD30.BIN with VIDTEX, when VIDTEX asks for a filename for your computer,
you would enter cad30.arc,p However, when downloading a Data Library
file with an extension of .IMG (SDLDR.IMG) using VIDTEX, do not add
the ,p to your computer's filename because then the file will not
download -- just enter the plain filename sdldr
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.