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BBC Disk Explorer (version 2.01)

IMPORTANT You use this software at your own discretion, the author will take no responsibility for any damages that may be caused by using this software. The software writes to your hard disk and so it is possible to damage files through the incorrect or correct use of this program. If you do not want to take that risk then please don’t use BBC Disk Explorer.

BBC Disk explorer is a program to manipulate BBC files and disk images in a similar way to Windows Explorer. The latest incarnation of BBC Disk Explorer has several improvements over its predecessors.

 New features

 Floppy disk support

 Task bar buttons


Task bar buttons

Files can be dragged and dropped from windows explorer ( or any other drag and drop compliant program ) on to an open disk image, as well as being dragged between images within BBC Disk Explorer.

The taskbar contains buttons which perform various operations on floppies, disk images and files. Click on the highlighted text below to find out the functions available:

Exit

Open

New

Extract

Delete

View

Compact

Properties

Help

About

It is also possible to perform certain functions through a pop-up menu which will appear when you click the right-hand mouse button over an icon in the left-hand pane.

To view the contents of a floppy disk just click on the floppy disk icon.


 Extracting files

To extract a file from a disk image:

-	Highlight the file or files you want to extract.

-	Then press the extract button on the toolbar.

A save file dialog box will appear to allow you to change the default filename and location which BBCExplorer will use to save the extracted file.

-	Edit the filename if you do not want to use the default filename.

-	Select a folder and drive in which to save the extracted file(s).

-	Then press the Save button.

A copy of the BBC file will be saved to the selected destination.

 Task bar buttons


Compact a disk image
 Compacting

When BBC disk images are copied from original disks, or disks generated by another disk imaging utilities it is possible for empty sectors to be left between files in the image. The compact button moves all the files in an image so as to remove these empty sectors, much like the *Compact command in the DFS.

To compact a disk image, select the disk from the list on the left hand side and then press the compact button.

 Task bar buttons


Exit
 Exit Button

This button closes BBC Explorer. Your disk images are saved as you work on them so there is no need to save any disk images before you close the program.

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 Deleting files

This button deletes all the files that are highlighted in the list of files in the right-hand pane.

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 Disk image properties

This button open a properties box for the selected disk image. The following properties are shown:

BBC Disk name:

This is an 7 character string which identifies the disk. An edit box is provided so that you can change the disk name. This name is set to the first 7 characters of the PC filename when the image is created.

PC Filename:

This gives the folder and filename of the disk image file stored on the PC.

Disk writes:

This is field used by the DFS to register how many times a disk is written to. This is set to 0 for new disks and is not used by BBC Explorer.

Number of files:

This simply gives the number of files saved in this disk image.

Total sectors:

This determines how many sectors there are in the disk image. This is 800 for 80 track disks and 400 for 40 track disks. New disk images created by BBC Explorer are always 80 track.

Used Sectors:

This fields gives the number of sectors occupied by the files on the disk. BBC Explorer always compacts files after an operation on a disk image, so this figure is usually the sum of all the files in sectors plus 2 ( or 4 for Watford formatted disks ) for the file list. If however, the disk image has not been compacted there may be empty sectors between files which will make the disk image larger.

Attributes:

This set of radio buttons allows you to choose the boot options for the disk. These instruct the DFS on how it should deal with the !Boot file on the disk. A new disk image is created by BBC Explorer with the None option. The Exec option executes the !Boot file, which should be a text file containing commands, usually to load and run a program. The Run option loads and executes the !Boot file which should contain 6502 assembler instructions. The Load instruction simply loads the !Boot file into memory ( I think ).

Use Watford Format (62 files):

This check box is used to swap between Acorn DFS and  Watford DFS disk formats.

When this box is checked and the Properties box is closed using the OK button the disk image will be changed to Watford format. It is then possible to save up to 62 files on the disk.

If this box is not checked, then when the Properties box is closed using the OK button the disk image will be changed to Acorn format. It is only possible to save up to 31 files on disk with this format.

WARNING If you swap back from Watford format to Acorn format and you have more than 31 files on the disk, all files after the 31st will be deleted.

If you press the any button except the OK button to close properties box then any changes you have made to the Disk image properties will be discarded.

 Task bar buttons


Open a disk image
 Open disk image

This button presents you with a file open dialog box, which allows you to select a disk image to open.

Once you have created a new disk image you can add files to it.

WARNING If you try to open or manipulate a file that is not supported or has the incorrect file extension then you may corrupt that file rendering it unusable for its original purpose.

 Task bar buttons


 Create a new disk image

Press this button to create a new disk image. The image you create will be in Acorn DFS format, to change this you should use the Properties button and put a check mark in the Watford format box.

To create a disk in a different format from the one selected ( the default is SSD ), simply select one of the other file types in the Create new disk box. The new disk image will be created according to the file extension that you have selected.

Once you have created a new disk image you can add files to it.

It is also possible to change the PC filename of the Disk image by clicking on the Disk image name once it is highlighted, then type in the new name and press Enter.

WARNING If you change the file extension of the image file it will not change the image file format accordingly, i.e. if you change a SSD file to a DSD file extension the file will remain Singe sided disk format but with double sided disk extension. This will mean that the BBC Disk Explorer will not be able to load the file because it expects to find a double sided disk.

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Adding files to a disk imagehlp_addfiles


 Help

This button displays this help file.

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BBC Disk file formats

The BBC Acorn Disk Filing System (DFS) can store up to 31 files on a single side of a floppy disk. Each disk could contain up to about 200K bytes of information. For average to large sized files this was plenty, but if you stored lots of small files then it was possible to use all the file name space before running out of space on the disk.

When Watford Electronics brought out their own DFS they decided to address this problem by increasing the number of file names that can be saved to a disk to 62.

Each disk is split into concentric rings called tracks which themselves are split into 10 sectors. The information that the DFS requires to load and save each file is stored in a list at the beginning of the disk, which occupy the first 2 sectors of the first track in the standard Acorn DFS.

The Watford DFS allocates the next 2 sectors ( sectors 3 and 4 on the first track ) to use for the extra 31 files. These 2 sectors contain the file information in the same format as the Acorn DFS, but are not read by the Acorn DFS. An Acorn DFS can only read the first 31 files of a disk using the Watford format, and if you try to write to a Watford formatted disk which contains more than 31 files you run a very high risk of loosing those files that are in the Watford part of the file list.

You can use the Properties button to swap between Acorn DFS and Watford DFS formats, by putting or removing a check mark in the Watford format box at the bottom of the properties box.

WARNING If you swap back from Watford format to Acorn format and you have more than 31 files on the disk, all files after the 31st will be deleted.

 Single sided format

 Double sided format


Adding files to an image
Adding a file to a disk image

Support for floppies is limited to read only at the moment, so while you can copy files from a floppy directly you cannot copy files to a floppy.

There are 2 methods by which you can add files to a disk image:

From windows explorer.

Open windows explorer at the folder which contains the BBC files that you want to copy to the Disk Image.

Open BBC explorer, and open or create the disk image that you want to copy the files to.

Select the disk image in the left-hand pane of BBC Explorer so that its files are listed in the right-hand pane.

Now select the files you want to copy in Windows explorer and drag them over either the list of files ( the right-hand pane ), or over the disk image name in the left-hand pane.

When the cursor changes from [image] to [image] then you can drop the files and they will be copied to the disk image.

BBC Explorer expects files to be in the standard format, that is using an INF file to provide the necessary DFS file information. However, if no INF file exists then default values ( of zero ) will be assigned for the DFS load address and execute address and a the default directory ( $ ) will be assumed. This means that any file ( as long as it fits on to the disk ) can be copied to a BBC disk image.

From Disk to Disk.

Open BBC Explorer and open the disk image(s) you want to copy files from and open or create the disk image(s) you want to copy files to.

Select the disk image that you want to copy a file from so that its files are listed in the right-hand pane.

Highlight the file(s) you want to copy and then drag them across to the left-hand pane and drop them on to the name of the disk image you want to copy them to.

The files will be copied across. If there is not enough space or the file already exists on the destination disk image then you will be prompted.


Disk image pop-up
Disk image pop-up menu

This pop-up provides an easy method to perform some disk image manipulation functions. The functions available from this menu, although they vary according to whether you select a disk image, a side or an actual disk, are:

New:

This performs the same function as the New button, it creates a new empty Disk image.

Close:

This closes the currently highlighted Disk image file.

Delete:

This will permanently delete the currently highlighted Disk image file from your hard-disk. You will be prompted before the deletion takes place.

Copy:

This will make a sector for sector copy of the original disk. Some disk protection schemes place data on to the disk in supposedly blank areas of the disk. This function will make sure that when a disk is copied all the sectors contain their original data.

Properties:

This will display the Properties box for the Disk image that is highlighted.


Viewing BBC files from a disk
 View

This is a new function which allows you to view the contents of a file either on a BBC floppy disk or a disk image.

To view a file simply highlight it in the right-hand pane of BBC Disk Explorer and either click the View button or double click  over the file.

The file viewer window will pop up and you can cycle back and forth through the sectors of the file using the blue arrows. When you have finished press the File Viewer’s Exit button and the File viewer will close.

If you have more than one file selected and you press the file viewer button only the last file you selected will be displayed.

 Task bar buttons


Improvements
New features (version 2)

BBC Disk Explorer has been improved in several ways.

1.	Support for double sided disks has been added. This allows the creation of disk images with two interleaved single sided disk images, which use the same format as that produced by BBCIM.EXE ( by Wouter Scholten ). These images can be either Acorn DFS format (31 files per side) or Watford DFS format (62 files per side).

2.	Support for reading BBC format floppies directly from your disk drive, much like FDC.COM ( by John Wilson and Wouter Scholten ), if your hardware supports it. The same restrictions apply to the use of this function as to FDC.COM which those of you who have tried to use it will probably already be familiar with. Some Floppy Disk Controllers have broken support for Single Density (SD) mode.

3.	A BBC File viewer has been added, so that you can browse through files on a disk.

1.	File selection has been improved so that you don’t have to only select contiguous blocks of files in an image. Now it is possible to select files using the Shift and Ctrl keys much as you would with Windows Explorer.

5.	A disk copy function has been added to the disk image popup menu. This will duplicate the selected disk, sector for sector. This is usefull for some copy protection schemes that ‘hide‘ data in free sectors on the disk, which would not be copied with a simple file copy.

If you have further suggestions, or information about bugs then please e-mail me.

 How to contact me


Single Density FDC Support
Single Density FDC support.

People who are familiar with FDC.COM will have already discovered whether they will be able to use the floppy drive support in BBC Disk Explorer. There is a description of the possible pitfalls in trying to use Single Density (SD) mode on some modern Floppy Disk Controllers (FDC) in a text file which accompanies FDC.COM, but for those who have not seen it here is a brief outline of the problems.

SD mode requires that the FDC uses a slower clock speed than is normally used in modern FDC chips. Some modern FDC’s like the Intel on my Pentium Pro are fortuitously able to work in SD mode, others less fortunate will not, it depends on whether they can generate this slower clock, usually indicated by the presence of 2 clock crystals on the FDC board.

I have read reports that given a couple of retries some FDC’s will manage it, if not then I am sorry but there is no more you can do, except maybe go and look for a really old FDC, or an FDC with an Intel chip on it ( even then there are no guarantees ).

There is also the possibility that some floppy drives will not support SD mode. I recently bought a TEAC 1.2MB drive in order to test this program, and found initially that it would not work in SD mode. I looked up the TEAC web site and downloaded the specification for the drive which included the jumper configurations. I found that it had been configured so that it would not read SD. I was able to reconfigure the jumpers so that it worked, but this led me to think that there may be some other drives out there that won’t work in SD mode at all. If this is a problem you might have to consider buying an older second hand drive ( they’re quite cheap because nobody wants them ).

 Floppy disk support


Single sided disk (SSD) formats

The BBC emulator community has used several different file formats for the disk images that they use. From what I understand, despite having different file extensions they are all exactly the same, a simple sector by sector, track by track, dump of the disk.

BBC Disk Explorer supports the following SSD disk image formats.

·	SSD 	This is the default image type, most commonly used.

·	IMG 	This is used by the pcBBC emulator (by Stuart McConnachie), and although it uses a different file extension it is exactly the same as SSD (  pcBBC now supports the use of SSD and DSD as well as all ADFS formats ).

·	BBC 	I can’t remember where I found this one, but again it is exactly the same as SSD.

You can create any of these disk image files, by pressing the new button and selecting a filename with the extension you want.

 Double sided format

 Acorn and Watford DFS format


Double sided disk format
Double sided disk (DSD) format

DSD format consists of 2 SSD images interleaved a track at a time. You can create a DSD image file, by pressing the new button and selecting a filename with the DSD extension.

If you want to change the Directory format between Acorn DFS and Watford DFS, then both sides of the Image will be changed at the same time.

 Single sided format

 Acorn and Watford DFS format


Using direct floppy support

After many trials and tribulations I have finally managed to add the ability to read directly from BBC floppy disks to BBC Disk Explorer. This has always been my goal from the very start, to enable me to copy the 200 or so BBC disks that I have on to CD Rom and make some much needed shelf space available.

There are however a few points to watch for when reading from floppy directly:

1.	BBC Disk Explorer will check your drives and see if you have any floppy drives present on your system. If not then obviously you won’t be able to read directly from floppies.  Both 3½ and 5¼ floppies are now supported, ( 3½ drives up to 1.44MB only ).

2.	If you do have a suitable drive available, then it will be displayed as an icon in the drive list on the left-hand side. To display the contents of the disk simply insert the disk, and click once on the drive Icon. You will then be able to drag files from the floppy across to disk images. If you do not refresh the directory each time you insert a disk then file copying operations will be based on the directory displayed in the right-hand window and not on the actual directory on the disk in the drive.

3.	The software that interacts with the FDC is still fairly rudimentary and stops BBC Disk Explorer completely while it is fetching data from the disk. It has no time out on the FDC operations and therefore if you have no disk in the drive, or the drive door is not shut properly, the drive light will come on and the BBC Disk Explorer will be frozen until a disk is inserted.

4.	The floppy disk is read only, at the moment there is no write to disk. I may change this in the future but for the moment I have no need for this facility, besides which you run the risk of screwing up the disks if it is not done properly.

5.	The software automatically detects whether the floppy is 40 or 80 track, and with a 1.2MB floppy drive (80 track) will put it into double stepping mode to read 40 track disks. It will also automatically detect whether it is a single or double sided disk.

6.	It might be possible to have your BIOS setup so that the floppy drive has different physical identifier to that reported by windows, i.e. your drive is connected as a B: drive but windows reports it as A:. In this case ( I wasn’t able to test it on my machine ) it is possible that BBC Disk Explorer may try to read a drive that is non-existent ( ie Drive A: because windows reports your drive as that ), and it will then hang.

I have tested this program fairly thoroughly but I can’t guarantee that it will always work for you. I have a Pentium Pro with an Intel motherboard and a single 1.2MB floppy drive, which I used to test the software. It is possible, and some would say probable, that people with different hardware may find that it doesn’t work for them. If not then please let me know how and why it didn’t work and I will do what I can.

 Single Density support


Contact me at

All suggestions and bug reports can be directed to me by e-mail at:

strawb@idiom.com

Please include as much information as possible when reporting bugs, including what hardware you are using if it is a floppy related problem.


About
 About BBC Explorer

This button displays information about BBC Explorer.

A program to create and manipulate BBC disk images on the PC for use with BBC computer emulators.

Version	: 2.01

Written by	: Laurie Whiffen.

Copyright	: Strawberry Software © 1998.

e-mail	: strawb@idiom.com

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