Philips/Data Recovery Project/converting backup tapes/dostoss

The main menu, as shown above, has some submenus, which I, for some reason, cannaot present as 'live' screen shots.

The 'DOS Util' item has 8 submenus,:

Set Root directory

This screen shot tells us where the back-up tapes are located.

Advice : Don't use the original files, but a copy.

Convert a backup tape to a disc image

What we see here, is an overview of all the directories found in the path as specified by the Root directory.

Selecting one of the directories, and pressing Run, will attempt to convert the contents of the TAPEMARK.xxx files. TAPEMARK is the filename given by the conversion program, so that will probably need to be altered when other programs are used. Let me know, and it will be changed.

The bottom of the memo will (hopefully) contain a text like this :

• ---------------------------------------------
• Checking pointers

• Pointers checked

• The image created corresponds to a 5 MB disc

• ---------------------------------------------

• This image originates from a 5 MB disc and

• contains addresses beyond the 2.5 MB boundary

• Compress or reorganize image before use.

• ---------------------------------------------

• Conversion for this user is completed

• Saving Memo to D:\philips\pts tapes\600103\memo.txt

• --------------------------------------------------

This gives us some important information. The back-up was taken from a PTS6876 disc, also known as X1216, which has a capacity of 5.0 MB (Mega, not Giga!) per cartridge. So, when you only have a PYS6875 disc, also known as X1215, you have a problem.

To solve this, you need to use either the compression/reorganize function (described later), or to move the User to a different disc. We will come back to that later on.

When the backup is restored, you can find it in the directory specfied by Root_directory + tapename, as a .DSL file, for example D:\philips\pts tapes\600103\600103.DSK

The directory D:\philips\pts tapes\600103\ is in fact used for all files relating to this backup tape.

View Image File Directly

This is a variant of the == Display Sector == menu item to be described a bit later.

This variant was needed in order to be able to inspect some backups from the University of München, as they were written with a sector length of 512.

What we can do here, is inspect any file, as we can specify the record length. We can do the usual things like Next, Show, Previous, etc. and specify the sector we want to start with. This sector number can be given as straight decimal (e.g. 517) or as a hexadecimal value (/29AB).

Backup of Disc Images

This menu item was implemented while under the assumption that we could use a PC as a kind of master depository for PTS disc images, so we could select which image to load to the simulated cartridges.

As the contents of these cartridges could be changed, it was prudent to have a copy of the original version.

As you can see on the screen shot, you can two ways to select a .DSK file :

1) specify the path directly

2) pick one of the .DSK files located under the Root directory.

The .DSK file will be copied to a new directory under the present one. The name of this directory is derived from todays date.

Reorganize a 5 MB disc

This procedure can be used to compress and reoganize a disc.

A 5 MB disc can be reorganized into a 2.5 MB disc, under the condition that it will fit.

If it does not fit, you will need to split the disc into two, for example the user SAG and the Monitor part onto one disc, and the application itself on another disc.

While copying, it will also reorganize the files, meaning that they (1) are defragmented and (2) that they are written sequentially from the start of the disc.

As usual, some statistics are written at the end of the memo.

Copy a discfile to Fixed Disc or Cartridge

We spoke earlier of the possibility to take back-ups of .DSK files.

This routine is the opposite : it copyies files from the depository (in lack of a better word) to one of the 4 discs supported : FIX0 and FIX1, resp. CART0 and CART1.

The screen shot also shows which disc image is present on the simulated discs, so you can determine whether you should take a back-up first, before overwriting the present image.

The Utilities

Extract a file

In order to be able to extract a file from any disc image, you need to enter 3 parameters :

1) where to find the disc image

2) The name of the disc image

3) The name of the file you want to extract

Pressing SCAN will present a list of files with that name.

It will eventually be possible to extract all *.SC files from a disc image, but that remains to be implemented.

If you want to inspect a source file (*.SC) you can select the file you want to see, and press Read Source.

This is the devicedependent table for the PTS keyboard driver.

Display a disc image sector

This is the proper way to display the contents of a sector in a .DSK file.

This time I selected sector 8, which contains the files belonging to the user SAG.

You can see that the Assembler Load Module starts in segment /0298.

A better way to inspect a file directory, is to select the relevant checkbox.

This is the moment to say that user-id's, directory names and file lists can extend over more then 1 segment. In the case of the screen shot above, just pres NEXT and you will see the remainder of the files being a part of this directory.

As the last "file", you will see 2 identical strange characters. These are the values for /FF, indicating 'end of list'.

I will take the opportunity to say that files with /00 as the first two characters, are to be ignored. /00 is the value for 'Deleted'. This can occur in all directories.