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G8MNY  > TECH     14.09.21 07:12z 137 Lines 6436 Bytes #999 (0) @ WW
BID : 46634_GB7CIP
Read: GUEST
Subj: Decoding BBS Data files (TEXT)
Path: HB9ON<IW2OHX<IW0QNL<ON0AR<GB7CIP
Sent: 210914/0711Z @:GB7CIP.#32.GBR.EURO #:46634 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                             (Updated Oct 15)
For those of you who are still unable to use these Packet BBS bulletins, here
is how to it manually.

The files are flagged as B$D in the BBS TSD field. They may contain data such
as pictures, programs, databases, sounds etc. often PKZip or JPEG compressed
which has then been encoded in 7+ format to go over the BBS text system.

ENCODING
~~~~~~~~
Data   Compressor   Compressed      BBS Text       Sent BBS
Files    Program       File         Converter     Text friendly
                                    Program          Files
.DAT \
.TXT ³                                            ³ SEND.P01  10K
.BAS  \___PKZIP________NAME.ZIP_______7Plus_______/ SEND.P02  10K
.COM  / or RAR32    Or a PICTURE.JPG              \ SEND.P03  10K
.EXE ³                 say 33k                    ³ SEND.P04   8K
.DLL /                                              Total=38k
Total=120k

The part files (normally more than one) are numbered in HEX, part 1 = P01, P02
up to PFF = 255 parts. File size by 7+ default is limited to about 10k, but
nowadays there is no good reason for this & larger files can easily be made
with the 7PLUS/SB=36000 switch to make up to 36k files!

Paket6.2 program includes scripts for making & sending them etc.
    
Inside a 7+ bbs data file as well as the usual BBS headers & tails you will
find this sort of thing...

  go_7+. 001 of 004 NAME.JPG     0076254 2280 08A (7PLUS v2.0) °±²Ûﺬ
 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data
 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data
            SAY 500 lines of no space gobbly gook data!!  
 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data
 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data 8bit data
  stop_7+. (NAME.P01/04)     [368961E5]                        °±²Û‰¸0

The 7+ part is less than 70 characters long per line, so no system should word
wrap it, there are no spaces, so no system should concatenate them, & there are
no special character sequence like CTRL C, ESC, etc. that will kill the comms
link. All lines are the same length so some Rx errors can be manually spotted.

DECODING
~~~~~~~~
 Rx  BBS    Rx LOG  Extract    7+      Decode Compressed Uncompress  Data
  Files      File     7+      Parts       7+      File    Program     Files
                   Program             Program                      / .DAT
(SENT.P01)³                 ³SENT.P01³                              ³ .TXT
(SENT.P02) \_.LOG___7PLUS__/ SENT.P02 \___7PLUS__NAME.ZIP__PKUNZIP__/ .BAS
(SENT.P03) /  43k    -X    \ SENT.P03 / or RAR32    33k             \ .COM
(SENT.P04)³                 ³SENT.P04³          or PICTURE.JPG      ³ .EXE
Total=42k                   Total=38k                               \ .DLL
                                                                 Total=120k
N.B. PKZIP, PKUNZIP, 7PLUS & RAR32 programs have /? or /H or -H help options.     

Before downloading them, you need a program called 7PLUS, & possibly PKUNZIP
or equivalents, you may well find these in the data area of your BBS where it
can be downloaded using Yapp, pP or Bacomm, data transfer protocols. Some
packet programs have the 7plus or Zip functions embedded for you.

THIS IS WHAT I DO
~~~~~~~~~~~~~~~~~
1/ List the message index on the BBS with the B$D messages of interest.

2/ Turn on your log file to record the download.

3/ Enter the BBS message Nos (e.g. R 497974 497973 497971 ) you may also want
   to log any descriptive text file, possibly to a separate log file. If the
   part numbers are consecutive or nearly so try.. R 497971-497974 as the order
   does not matter nor does the odd unwanted file.

4/ When finished (it may take quite a while) close the log file. It does not
   matter if other items are logged as well, but not from another stream! You
   can do this again & again until you have all the parts needed in a log or
   logs.

5/ Put these log(s) file into a separate directory (folder) with the decoding
   programs (e.g. C:\PAKET\7PLUS ).

6/ Extract the 7+ parts from the log or logs...
   e.g. 7PLUS APR10.LOG -X
   This should give you the same Hex numbered parts as was sent.
   e.g. FILENAME.P01 FILENAME.P02 etc.

7/ Now decode the 7+ parts into one file.. same command but with no -X
   e.g. 7PLUS FILENAME
   If there are no errors, this give you the sent file. e.g. FILENAME.JPG
   or FILENAME.ZIP

8/ Unpack the ZIP file, you need PKUNZIP. e.g. PKUNZIP FILENAME
   to give the original files... e.g. FRED.DAT, FRED.BAS, FRED.EXE etc.


Once you have unpacked the picture, programs, data, etc. & it works, don't
forget to tell the sender it worked/failed etc. & what you had tried it on.

Then for good housekeeping install the item in a suitable directory (folder) &
set up Windows desktop to open it etc. Purge out the old transfer files from
the 7plus directory.

As you can see the whole thing is not that friendly done manually, if you write
a batch file to handle the procedure, it will make it far more convenient until
something goes wrong!

As I have said before, BBS SYSOP have to vet BBS content, & any difficulty in
doing this often results in message deletion. Just 1 message part astray or
damaged means the whole lot is a waste of space on the BBSs, & complex 2 way
error procedure between the recipient & sender is needed to fix it. This is not
always possable as the BBS SR or SP routing tables are different to the multi
routing used for the original SB, so your reply may never get there! 

This is why for most things I prefer the EVERY EFFICIENT ASCII GRAPHICS if it
will do the job.


Of course you can write/use a script macro to do all the above for you
automatically.
Dave VK2AWZ @ VK6ZRT writes.. Ok John on decoding 7+ files manually, and it
certainly is a long process! However Winpac 6.8 does it automatically, when one
has downloaded the 7+ files. What happens is that when the last one is received
up jumps the inwards message icon, that says that the files are decoded and
picture number (xxx) is stored in the decode directory. I go to this directory
with Windows explorer and click on the respective xxx.JPG, that activates my
preferred pictures program! 73 - Dave, VK2AWZ @ VK6ZRT

I6KZR Renzo writes he does it automatically with SALLY 7.


Why don't U send out an interesting bul?

73 De John, G8MNY @ GB7CIP


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