Emulation: BBC Explorer

By Dave E

Originally published in EUG #65

In our fifth article discussing the most useful Electron utilities available on the modern PC, we turn with an appraising eye toward BBC Explorer. Its user guide describes it as 'a utility for the PC designed to help you extract, add or move standalone BBC program files between real BBC floppy disks, disk images and web sites that offer individual file downloads'. If this wasn't handy enough, the cleverest thing about the program is its wonderful 'point, click and drag' handling. It works just like the familiar Windows Explorer - and this means that you can pick up how to use it almost instinctively.

The latest version of BBC Explorer is v2.00. Available free from all the usual BBC web sites, it is limited only in that it works just with discs on the DFS format. However, because this is a popular format on the Acorn Electron as well, the application is just as useful to Elk owners as BBC owners. This is particularly the case when BBC Explorer is combined with the utility PPM2BBC, which we'll take a look at in the sixth article in this series.

The first thing that grabs you when you've downloaded, unzipped and launched BBC Explorer is the impressive GUI (Graphical User Interface). It runs in a window sized about 65% of the screen and is divided, as Windows Explorer is, into two roughly equal sized columns. Across the top of the window runs a bar of ten icons. All have both symbols and straight-forward explanations. From left to right, these are Exit, New, Open, Extract, Delete, View, Compact, Properties, Help and About. There are no pull-down menus. To activate an option you click on the icon once.

The great news is that BBC Explorer provides an interface for a whole host of emulation formats. In the Electron world, the suffix .ssd on a file is a single sided DFS disc image; the suffix .dsd on a file is a double sided DFS disc image. However, the BBC emulation world doesn't have it so easy. There is .ssd, .dsd and two more DFS formats: .img and .bbc. Although both of these extra formats are identical hexadecimal images, many BBC emulators are not equipped to handle all formats. As an example, BEEBEM (the best loved free emulator), like ELECTREM, only loads/saves .ssd and .dsd files. But PCBBC (an ultra-fast, ultra-brilliant emulator which costs £10) only loads .bbc files. As long as PCBBC rules the roost, we're not going to see the .bbc format disappear - hence a tool is certainly needed to convert one type of image to another. Particularly as the 'daddy' web site of disc images, Stairway To Hell, supplies nothing but .ssd and .dsd images.

To get started with BBC Explorer, try opening any disc image stored on your hard drive. The two areas that are blank on launch change instantaneously. In the left area, the name of the image appears, nicely idented, in a hierarchical tree. Below this name, and idented a little more, are the descriptions 'Side 0' and 'Side 1'. Left clicking on one of these brings up in the right area all the information (and more) usually found on the original machines by executing a *CAT command. Right clicking allows you to view the 'Properties' of the whole of the disc image.

If you open up another disc image, both images remain in the 'tree'. That is, the second image you open does not discard the first. In fact, you can open up as many images as you want and by clicking any of them BBC Explorer will instantly report the statistics. Along with the PC disc image filename, and for both sides, it gives you: the BBC Disk Name (which you can change with the keyboard), the number of times the disk has been written to, the number of files currently stored on the disk, the !BOOT option and the number of sectors used (An eye-pleasing blue and purple pie chart illustrates this last option!).

The true beauty of the package comes from the ease with which, when more than one disc image is opened, the user can drag individual files from one disc image to another. For BBC users, and because of the complications with the multiple DFS image formats, the benefits are obvious: They can open a .ssd image, create a .bbc image (with 'New') and then drag all the files from the .ssd image to the .bbc one. The result is an incredibly quick conversion from one format to another and they can then use the .bbc image in their emulator of choice.

For us spoiled Electron owners who do not have to go through any such rigmarole because there are no other formats, the benefits are less self-evident. But BBC Explorer's facilities can save a lot of time if you work with a great many discs. For example, if you want to compile a disc image of your favourite games, as long as you keep within the limit of 31 files to a side, you can do so by clicking and dragging quite easily. The alternative would be to download each game as a disc image and painstaking *COPY across the files on a real Electron.

In addition, note that the oldest surviving archive web site for the BBC, The BBC Lives, supplies its .zip file downloads as individual files. Doubtless this is due to the proliferation of different disc image formats on the Beeb and to ensure compatibility with the Archimedes range. So without BBC Explorer it is impossible to play any games, BBC or Electron, downloaded from this particular web site.

To elaborate on this point a little further, try downloading a game from Stairway To Hell (or indeed www.acornelectron.com). Inside this .zip file will be a .ssd or .dsd image (Chuckie Egg, for example, is "ha-chuc.ssd"). Now try downloading a game from The BBC Lives. Inside that .zip file will be a selection of files ("Chuckie", "Chuckie.inf", "Ch_Egg" and "Ch_Egg.inf"). To use the files from the latter, you need to select 'New' on BBC Explorer, create a disc image in the format suitable for your emulator then tabulate to WINZIP, highlight each of the four files then click and drag them from the WINZIP catalogue into your created disc catalogue, repositioning the Windows as necessary.

The same click and drag procedure works for all files stored in the disc image catalogue displayed by BBC Explorer. You can therefore remove files as easily as you add them, either by clicking the 'Extract' icon and then saving the files to a selected folder or by positioning Windows Explorer in the background and highlighting files to be removed then dragging them from one "Explorer" utility to the other.

The other options are not superfluous either. The 'View' option will display a word-wrapped text file on screen or a hexadecimal dump of a program. The 'Compact' option will compact the contents of a disc image, typically in the blink of an eye while the same procedure on a real Acorn machine might take several minutes! The 'Help' option also outlines some of the information found in the User Guide.

According to the User Guide by Laurie Whiffen (also the author of the utility), BBC Explorer also offers 5.25" Floppy Support, i.e. it recognises any 5.25" drive connected to your PC and can read from (but not write to) genuine BBC discs inside it. Judging by the excellent quality of the rest of this piece of software, there is no reason to doubt this claim, although I personally have not attempted to use this feature. The documentation also includes a helpful chapter on Disk Format Information, giving some background information on the .ssd and .dsd formats. (It also discusses the Watford Electronics' disc format as well, which will be familiar to BBC owners.)

At 14 pages, the User Guide is concise and its step-by-step instructions, combined with the very user-friendly program itself, make BBC Explorer an extremely easy piece of software to use. I thoroughly recommend it not just in itself but because, in the very next article, we'll see how it becomes an essential part of a much larger project - designing screens on your PC and converting them to your BBC or Electron to achieve jaw-dropping results!