Writing floppies for the Amiga

So this is more of a part 2 to ‘Retro Computing and loading stuff‘ . One of the challenges I have with the Amiga is getting data from ADF images onto real floppy disks. Initially I used transwarp using a null modem serial cable. I was using linux as the source system, and without going into heaps of detail you can effectively ‘cat’ your adf file into your PC serial port, and then on the Amiga end run transwarp with appropriate arguments to get it to read the serial bit stream and write it to a blank floppy in the Amiga.

Using transwarp worked quite reliably after a few hurdles (I had to use a native serial port instead of a usb serial one, and formatting the floppy before writing to it seemed to ‘work better’). I only got it working at 19200 bps which takes about 7 mins to transfer a disk, plus add into that 40 secs or so to format a disk. It is certainly not quick, but it gets the job done.

So I was keen to get ADTWin to work. It is a significantly faster method of writing Amiga floppies using a PC. The basic requirements for ADTWin is a PC with Windows installed, a parallel port on this PC, a PC floppy drive, a power source for this floppy drive AND a special cable that connects the DB25 of the parallel port to the 34 pin IDC connector of a floppy drive. I guess the hard part for most people is ‘making the cable’, but it is pretty easy to make and there are very clear instructions on how to make it on the ADTWin page. For me, ADTWin seems pretty amazing. The ‘exact timing’ requirements of writing a bitstream to a floppy is well .. ‘exact’ … and not exactly something that Windows (or any other modern OS) can do well.

For me, I don’t have any computers that have a local copy of Windows installed … and then I needed one with a parallel port too. My main goal was to use my old Thinkpad T42 since its quite portable and has a parallel port. So I installed an old version of Windows XP, installed ADTWin, made my cable up, hooked up an old ATX PSU with green tied to GND, powered it on, then powered on the T42 and tried ADTWin. It told me there was no drive detected. This was a little soul  destroying. But then I figured that ADTWin is using he parallel port in traditional output only mode … so into the T42 BIOS and switched the parallel interface from bidirectional to output only. Now ADTWin detected the drive, but the disks it wrote were unreadable by my Amiga … and when I used ADTWin’s ‘Test’ function it told me that there was a very low likelihood of the disks being readable on the Amiga.

At this point I actually pulled a core2duo motherboard/cpu out of the cupboard, and set everything up on it again under windows and tried ADTWin again. This time the disks I wrote worked a bit in the Amiga. Then I tried ADTWin again, this time turning off ‘pre compensation’ and they worked perfectly on the Amiga.

So I thought I’d have another look at the T42 (I didn’t want a whole ATX board and CPU dedicated to floppy making). Again, I had a look at the BIOS. The only other thing I could change on the parallel port config was the IRQ. Default is 7, so I set it to 5.

I tried ADTWin again on the T42 and with pre comp off the disks were now read perfectly on the Amiga (I did also set the T42 battery maximiser to operate in ‘High Performance’ mode). And this time round ADTWin’s ‘Test’ button was telling me that there was a 95 or 100% likelihood that the disks would be ‘good’. All good.

So ADTWin works quite well and is very quick writing disks.

Of course you’re probably wondering why I didn’t just buy a gotek floppy emulator and get it working on the Amiga. The thing is I have … and that is the subject of part 3.