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Atari Mega Archive 1
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ZFLASH.DOC
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1991-11-12
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9KB
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Zmodem Transfer Shell v1.20 for
Flash v.1.50 upwards
(c) 1988 by DeltaVision Systems
Written by J. Webb
---------------------------------------------------------------------
What is Zmodem?
---------------------------------------------------------------------
Zmodem is a fairly new transfer protocol. It has a lot of
features which other protocols don't have...
1) It's MUCH faster than Xmodem or Ymodem. Tests show an average
throughput of more than 90%. Transfer of large files might
even reach 98 or 99%. Compare that to standard Xmodem (approx.
60%), Ymodem (70%), and that's if you have a GOOD connection.
2) Zmodem has a variable block size (they're called 'packets' in
Zmodem). This means it will reduce the size of each packet if
a lot of errors occur. If, say, with Xmodem-1K an error occurs,
the whole Kb must be resent. If this happens with Zmodem, it
will reduce the size of the packets, so that if another error
occurs it won't have to send TOO much again.
3) Xmodem and Ymodem use either Checksum (8-bit) or CRC (16-bit)
error checking. Zmodem however uses 32-bit CRC, which improves
the reliability of the protocol.
4) If, say, during a transfer the carrier is lost, Zmodem can
resume the transfer from the point where it went wrong. Very
nice if you're transfering large files.
5) Zmodem is a batch protocol, which means you can transfer more
than one file at once.
These are just a few of the Zmodem features. There are a lot more,
but these are the most important and handy. If the BBS system supports
Zmodem, use it!
--------------------------------------------------------------------------
What is ZFlash?
--------------------------------------------------------------------------
For some reason or other the authors of the main comms packages on
the ST are too lazy to implement new protocols. In the PC world a comms
package without Zmodem, or without the ability to use an external protocol
(like in Procomm Plus) isn't taken seriously. It's about time people using
an ST start thinking this way.
Flash is one of those programs. One of the best, I think, but it
doesn't support anything faster than Ymodem Batch. I had some Zmodem
sources, and decided to get them to work as stand-alone receive and
transmit modules. To control the two .TTP programs, I thought it would be
handy to have a shell which could be executed from within Flash. That's
what ZFlash is all about. It has a small terminal emulator, Zmodem Send
and Zmodem Receive.
--------------------------------------------------------------------------
How to Install ZFlash
--------------------------------------------------------------------------
I assume you've unARCed the ZF110.ARC file, otherwise you wouldn't
be reading this now. Place the files from the ARC in a directory, doesn't
matter which. Now edit the file ZFLASH.CFG. This is a little configuration
file, and contains your default DOWNload directory and UPload directory,
in that order. It also contains some preferences, and looks like:
Download Directory
Upload Directory
Use Gem?
BBS Mode?
Protect Files?
Sound On?
An example would be:
d:\comms\download\
c:\upload\
1
0
1
1
'Use Gem' defines whether ZFlash defaults to file selector mode or not. If
you want to use a file selector instead of the command line, but have set
Gem mode off, enter a '?' as the first character of the line.
'BBS Mode' is something I built in for Sysops. If you've downloaded a file
ZFlash will ask for a description, and add the file to FILES.BBS. If you
enter a blank description, the file will not be added.
'Protect Files' defines whether ZFlash must protect files with the same
name. If - say - you have a file called MYFILE.ARC, and the other side
starts sending a file with the same name, ZFlash would either abort or
overwrite the file.
'Sound On' is for if you don't like the beeps which ZFlash gives on
completion of the transfer.
By the way, ZFLASH.CFG can be either in the default (current) directory,
or in the directory to which environment variable FLASH points (for people
who use a command line interpreter).
---------------------------------------------------------------------------
Using ZFlash from ... FLASH!
---------------------------------------------------------------------------
Next, load Flash, and select 'Edit Function Keys'. Choose an empty
key, and enter the following line:
>GEM [zflash program]|
where [zflash program] is the path and name of Zflash, i.e.
>GEM d:\comms\flash\zflash.prg|
Don't forget the vertical bar at the end! Save your function keys, and
press the key you've just defined. You should get the ZFlash menu.
---------------------------------------------------------------------------
Using ZFlash
---------------------------------------------------------------------------
The menu looks something like this:
[R] ......... Receive Zmodem
[S] ............ Send Zmodem
[T] ...... Terminal Emulator
[Q] ................... Quit
Pressing 'Q', 'ESC' or 'UNDO' will take you back to Flash. Pressing 'T'
gets you in the terminal emulator (for last minute stuff), 'Undo' returns
to the menu when you're in the emulator.
[R] starts up the Zmodem Receiver. It will ask you for the directory where
your downloads should be placed. Enter a '?' as the first character if you'd
like to use a file selector instead of typing. The directory must exist, to
abort enter an empty line, or ESC.
[S] is for Sending one or more files. Wildcards are supported. Again,
press '?' to get a file selector.
You can also use the cursor key to move the highlight, and press Return to
choose an option.
---------------------------------------------------------------------------
Standard Disclaimer
---------------------------------------------------------------------------
I can not be held responsible for any damages which might occur due to the
use of ZFlash. If you use any of the files in the package, it's entirely at
your own risk. You might turn your 80 Mb harddisk into a 360 floppy, hey,
I'll probably try to sell you another one...
---------------------------------------------------------------------------
Sources & Copyrights
---------------------------------------------------------------------------
The Zmodem sources used were in a package called ZMDM.ARC which I found
somewhere. I think they were ported by a group who call themselves 'ST
Enthusiasts at Case Western Reserve University'. They were rather buggy,
I hope I fixed quite a few 'undocumented features'.
Zmodem and probably Ymodem are Copyrights of Chuck Forsberg, Omen
Technologym, and are quite likely to be trademarks too...
Flash is Copyrighted by Antic Publishing.
ZFlash may be distributed freely as long as you stick to the following
rules:
1) You do NOT charge ANYTHING for the package
2) You distribute the complete package, including this document
3) You may post ZFlash on a BBS as long as all users may d