GUIDE TO FDC.COM
By Dextrovix / RetroBBCWhat is it?
FDC.COM is a utility that you can use to read and write BBC disks on a PC. I've had quite a bit of mail on the subject, so I thought I'd try and explain some simple ways of getting it to work. I'm not an expert by any means, but I have had success, although copious amounts of patience, swearing, coffee and nicotine have helped!
Hardware requirements
Obviously, you will need a 5.25 inch drive in your PC. I had, in 1996, used my Cumana BBC drive successfully within my PC, but I had to alter some jumpers which meant DOS couldn't read PC disks, but FDC could read BBC ones. I cannot remember how I did it, so if anyone has managed it (and it could have been my motherboard, or an older version of FDC) then let me know!
Whilst still on that subject, I have tried to get my current BBC Midwich (Matsushita mech) drive working, and I'm sure I've tried all jumper combos, but FDC just spins the disk then displays a seek error.
From the hardware point of view, any PC 5.25 inch floppy drive should be okay (mine is Mitsumi) as long as it is double-side and double density. According to the documentation, more success seems to come from newer motherboards with up-to-date floppy controllers, although I remember it worked even on my crappy 386 with separate I/O card.
Software requirements
DOS, version 3.3 and up. It works okay in Windows 9x DOS boxes. NT and Win 2k do not work because the program cannot write directly to the hardware. Incidently, ARCIMG for the Archimedes emulator has the same problem for the same reason.
Using FDC
The documentation includes can be heavy going, but it pays to understand it. The following is a brief and direct way of getting software from BBC disk onto your PC for emulation purposes. Read the documentation if you want to be more exotic with the settings, like writing back images to work on a real BBC which also works.
Load FDC from the command prompt.
This should turn your normal DOS prompt to
FDC>
Firstly, you need to set the drive you are using. If your 5.25 inch drive is a drive A: in DOS, then you need to type FD0 to tell FDC which drive to use. Similarly, if you have it set as drive B:, you need to type FD1 (which is the default).
To initialise BBC-compatibility mode, type BBC and press <ENTER>.
Depending on whether you're using 40 or 80 track disks, type CYL 40 or CYL 80 respectively.
If you're using a 5.25 inch drive that is a high density model (1.2mb capacity in DOS), then you'll need to type DDINHD, which sets the data rate to correctly read a double density disk using a high density drive.
To read the disk contents of your BBC disk on the PC as one file (which can then be used in pcBBC for example), type in READ0 FILENAME.IMG and press <ENTER>. Provided your disk is error free, all 40 or 80 tracks are read and stored in the current directory on your hard disk. READ0 reads the upper surface of the disk. If you have data on the under side too, then substitute READ0 for READ1 instead.
If you are unfortunate enough to have some errors, the process stops. You can override this by typing in CONT before you start the READ0 process. However, if these portions of the disk contain data (as opposed to being blank when it wouldn't matter), then you may encounter crashes/freezes when your emulator attempts to load the corrupted files off of the disk image.
Finally, typing QUIT returns you to DOS.
Example:
FDC <ENTER> Loads the program
BBC <ENTER> Sets FDC to read BBC disks
CYL 80 <ENTER> Selects 80 track format (use CYL 40 for 40 track)
DDINHD <ENTER> Used if you have a high density PC drive, not required if only 360k drive
CONT <ENTER> Ignores I/O errors
READ0 ELITE.IMG <ENTER> Stores the contents of upper surface of disk to HDD
QUIT <ENTER> Quits FDCYou can also write to 5.25" disks from your PC to read in on your BBC, simply by substituting READ for WRITE.
FDC <ENTER> Loads the program
BBC <ENTER> Sets FDC to read BBC disks
CYL 80 <ENTER> Selects 80 track format (use CYL 40 for 40 track)
DDINHD <ENTER> Used if you have a high density PC drive, not required if only 360k drive
CONT <ENTER> Ignores I/O errors
WRITE0 ELITE.IMG <ENTER> Puts the contents onto the top surface of the 5.25" disk
QUIT <ENTER> Quits FDC
This article originally appeared on the RetroBBC website.
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