Magic Shadow Archiver

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Magic Shadow Archiver hereafter referred to as MSA is Copyright (C) 1987 by Steve Feinstein. MSA is distributed under the User Supported software or 'Shareware' concept. If you find this program useful and decide to keep and use it please compensate the author for his efforts and register by sending a check or money order for the sum of $10.00 to:

Steve Feinstein 56-26 244 Street Douglaston, New York


MSA may be copied and distributed freely provided it is not modified and this documentation is included along with the two program files.

MSA may not be included with any other product for any reason whatsoever without the written permission of the author.

No charge may be levied for a disk containing MSA except for a disk handling charge of up to $8.00.

With all the various emulations that are being implemented on the ST the need for a means of transferring or storing data contained on disks of the various system formats, easily, from TOS has become a necessity. MSA is an attempt to satisfy this need.

Though all precautions have been taken to insure that MSA will function properly the author cannot accept any responsibility for any damages that may result from it's use or missuse.

Please report any bugs and/or suggestions by dropping a note to the above address.

T h e M a g i c S h a d o w A r c h i v e r

MSA creates an image file of any unprotected disk that contains 512 byte sectors and writes it to a standard ST file using a simple track compression algorithm. This includes disks written under:

  • Atari ST/TOS
  • Magic Sac
  • CP/M

This means you can store or backup and then re-create any unprotected disk of various operating systems directly from the ST desktop. For instance bulletin boards can now easily handle files of entire Public Domain, Share Ware or Demo program disks in Magic Sac, IBM, TOS and other formats which can be Up/Downloaded and then restored to their original form ready to use with all boot sectors, roots and subdirectories intact.

Using MSA

STORING A DISK - To create an MSA archive file just boot MSA.PRG and after the functions panel appears place the disk you want to archive into the source drive A or B (this may be set using the buttons in the 'Drive' box at lower right off the panel - the default is drive A). To enter a name for your MSA archive file and set the destination drive/partition click on the long rectangular box at the bottom of the main panel and a standard GEM directory box will appear. Click on OK when you are finished making your entries. The name FILENAME.MSA will be used if you neglect to enter your own filename.

At this point you can click on the 'Do it!' button and MSA will start off by checking the source disk's format and display how many sides, tracks and sectors per track in the 'Information' area. MSA will then continue by reading each track of the source disk writing to the destination drive/file as it goes. To the right of 'Information' area you will see four fields that display the track being read/written, the side, the status of the operation (will show error codes if they occur) and the compression effectiveness for each track.

When the archiving operation is finished you will be presented with a box showing the size of the original disk, the size of the MSA file and the total compression acheived. This file now contains an image of your disk including the format information that will be used by the 'AUTO-FORMAT' function to re-create it.

Re-creating A Disk From an MSA File

To re-create a disk from a stored MSA file place a blank disk into the destination drive (set A or B by using the 'Drive' box at the lower right of the main panel) and click on the 'DISK -> FILE' button at the lower left of the panel. This will change the button's markings to 'FILE -> DISK' and the 'AUTO-FORMAT' button to the right will become enabled. Enter the name of your stored MSA file and source drive that you will be restoring from by clicking on the filename box at the bottom of the panel. Now click on 'Do it!'. MSA will format and create a new disk which should be an exact image of the original.


There are a number of user selectable or editable options that you will find useful when using MSA.

ANALYZE - The 'Analyze' button allows you to check the format of a source disk before actually creating an MSA archival file. Place your source disk in the selected drive (A or B) and click on 'Analyze'. The number of sides, number of tracks and sectors per track will be displayed in the 'Information' area.

MSA uses this function automatically (unless the 'Override' button is set) when creating an archive file. The 'ANALYZE' feature works on most standard formats used in the above operating systems. MSA will 'Automatically' copy and restore disks within these format ranges:

  • Single/Double sided
  • 80 tracks or more per side
  • 8 or more sectors per track (512 bytes per sector)
(11 [or more] sector destination disks must be pre-formatted.)

Since the operating speed of MSA was of major concern the analysis was kept within these ranges. (Forty track IBM disks may be set using the 'Override' button.) Because MSA is intended to work on different system disks the format analysis is made of the physical track/sector format of the disk and not through the system format data on the disk. Disks that have been formatted and reformatted with various capacities or systems can fool MSA into doing the wrong thing. Usually you will end up with an unecessarily large file but care must be taken to insure that these messy disks are stored properly by using the 'Override' feature and entering the format parameters manually.


At this time MSA uses a rather rudimentary data compression algorythm. It simply checks for strings of contiguous bytes of similar value and stores them in short encripted form.

Disks containing many empty sectors or repeated bytes (such as graphics files) will result in the smallest files. You can further compress your MSA files by using other compression programs such as arc.ttp, arca.ttp, etc. Note: smaller systems may not be able to arc the larger files created by MSA as with double sided disk files. These disks may be stored in segments or sections. i.e. tracks 0-39 as FILE_A.MSA and 40-79 as FILE_B.MSA on a DS/80 track disk.

Segmenting A Disk Image

To break a disk down into multiple MSA files click on and 'select' the 'Override' button before you start the archival operation. Then set the starting and ending tracks by clicking on the 'Tracks:' field. Change the starting and ending tracks to your needs and after placing the source disk in the drive proceed normally by clicking on the 'Do it!' button. Remember to use descriptive names for each section of the disk saved (for your own reference). MSA handles all the rest. MSA's 'Auto-Format' feature will restore each section to it's proper position on the disk when recreating the disk. Sequence is not important.

The Manual Override Button

The auto-analyze feature can be toggled off by clicking on the 'Override' button. This will deselect this feature. This is useful when storing disks that have previously been formatted as double sided but now contain single sided information. i.e. A disk that was used as a double sided TOS disk and then used as single sided Magic Sac disk containing ported Mac program files.

If MSA finds a second side on a single sided format it WILL copy it so use the 'Override' to set MSA for 1 side if that is all you want stored. An easy way to check is to use the 'Analyze' feature alone before you start actually storing the disk. This will tell you if MSA thinks there is a second side.

Aborting An Operation

Pressing and holding down either mouse button will abort a store or restore operation if you need to do so. When the disk is being checked with the 'Analyze' feature you must wait for it's completion before you can abort.

IBM or MS-DOS disks

MS-DOS or IBM program disks are usually double sided but often use only forty tracks (0-39). You can save time as well as avoid an oversized MSA file by manually setting MSA for 40 tracks. I'm sure that many PC-Ditto disks have previously lead lives as ST TOS disks.

Standard format for IBM or MS-DOS (v3.x) disks:

  • Tracks 40
  • Sides 2
  • Sectors 9

DOS system disks

IBM DOS system disks can be copied and restored with the system boot sectors and DOS version formats intact and ready to run. MSA may also be used with 5.25" drives.

Magic Sac disks

Magic Sac disk format is as follows:

  • Tracks 80
  • Sectors 10
  • Sides1 or 2

One of MSA's most useful applications is the transferring of Magic Sac disks.

We feel that the Magic Shadow Archiver will quickly find a place in your utilities box as you discover more ways using it. Please feel free to drop us a note regarding any problems as well as suggestions for improvements.

Bill Kokoni

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