Frequently Asked Questions Swapping disks with other computers can be a tricky business. John Kennedy tackles some of the more common problems. Q. Why can't I use PC disks on my Amiga? A. There are several reasons. First of all, most disks used with IBM-PC clone computers ("PCs") are High Density floppy disks and Amigas (with the exception of some late A3000s and all A4000 models) use Double Density disks. A High Density disk can be identified by the extra square hole in the corner: it looks like the Write Protect tab but has no little movable shutter. It is possible to buy a third party High Density disk drive for use with the A1200, and as a result you can store twice as much data per disk. Q. But can an Amiga with a High Density disk drive read PC disks? A. Not by default. As you know, disks must be "formatted" before they can be used. The formatting procedure divides the disks into a number of tracks and sectors. This organisation is necessary for the disk operating system to be able to read and write to and from the disk. However, the Amiga uses a slightly different formatting method from the PC, and as a result can squeeze slightly more data onto each disk. With hindsight this was probably a mistake, as although physically the disks are identical, the difference in formatting means they cannot be swapped between machines. Q. You're kidding! A. Nope, it's true -- but as you would expect a lot of things can be fixed with software. For example, from Workbench 3 (as supplied with the A1200 and A4000) onwards, a special "DOS Driver" has been included with the system software called CrossDOS. This is a special program that creates a virtual PC-compatible floppy disk drive called "PC0:". It doesn't matter if you don't have a High Density drive: a PC can still read and write to Double Density disks, although obviously it can't store as much information as on High Density ones. To start the CrossDOS system working, find the drawer called Storage which is part of the Workbench system. In the drawer named DOSDrivers you'll find an icon labelled PC0:. Double-click on it and a new icon should appear on the Workbench. Copy this icon into Devs/DOSDrivers if you want it to be present all the time. Alternatively, opening a Shell and entering "mount pc0:" will have the same effect. The PC0: drive is actually your normal df0: Amiga disk drive, however when you read and write to PC0: the data is read and written in the correct format for PC disks. You can even format PC disks in this way, although I have occasionally had problems and find in general it is better (and faster) to format the disks on the PC if at all possible. The Amiga drive df0: can still be used. If you have an external floppy it is possible to create a PC1: device so that it too can behave like a PC disk drive. Q. I don't have Workbench 3, what can I do? A. Either upgrade to Workbench 3.1, or purchase CrossDOS separately. There are also programs in the Public Domain (such as MessyDOS) which will achieve the same result. Q. When ever I copy text files from PC0: I get extra lines appearing. A. Linefeeds and carriage returns are dealt with differently by Amiga and PC programs. Find the Commodity called "CrossDOS" on the Amiga workbench. It includes an option to strip the extra linefeeds. Q. How can I transfer data to and from an Apple Mac? A. There is no easy way to emulate the Apple method of formatting disks (which causes the disk drive to spin at different rates). The good news is that all Apples come with a program called "Apple File Exchange" which can read PC format disks. Newer Macs (with System 7.5) can read PC disks even easier. Hardware Mac emulators (such as the excellent Emplant) can use the Amiga disk drives to read and write Apple disks. Emplant can also use the AppleTalk networking system, so you could swap files to and from a real Mac in this way too. Q. When using CrossDOS my Virus checker goes nuts. A. Yes, annoying isn't it? The Virus checking software knows there is an extra disk drive present (PC0:) but can't read it -- and therefore warns that there may be a virus on the loose. You will either have to put up with the warnings or switch off the checker until you have finished using PC disks. Q. If I can read PC disks, does that mean I can run PC programs? A. No, so put away that disk with Doom on it. Being able to read disks is one thing, using programs written for a different machine is something else. For example, it is possible to share image files and MOD tunes between the PC and Amigas as these are only data files, but programs are completely different. A PC program expects to run on a PC operating system (such as MSDOS) and requires an Intel (or compatible) processor to be present -- as well as a graphics, sound and I/O card with memory is certain fixed locations. Some programs (such as PC Task) will attempt to emulate a PC on an Amiga, by running a program which appears to mimic the Intel processor and other dedicated PC hardware. However, as the Amiga processor is effectively running a program running a program, it's not a very fast process. Don't expect Windows to work very well, if at all. Hardware solutions such as BridgeBoards (which are fitted into the Zorro slots in an A2000, A3000 or A4000) are now very hard to come by, although they worked extremely well as they included a real Intel processor on-board. These boards even allowed dedicated PC expansion cards to be fitted inside the Amiga. Q. Is it worth upgrading my A1200 to a High Density disk drive? A. Only if you have already fitted a hard drive and some extra memory. A High Density disk drive is most useful for backing up hard drives and swapping data with PCs.