How do I transfer Amiga disks?

From Jonathan's Reference Pages


A common question on Amiga forums is, "How do I transfer data to/from an Amiga"? You may wish to transfer Amiga disks to a PC to use in WinUAE, backup data from an old Amiga, or copy software to an Amiga from the Internet.

You have two problems to solve. The first is how to transfer data between Amiga and PC, when PC disk drives cannot read Amiga floppy disks and the two share no networking standard by default. The second is how to copy a floppy disk into a format a PC can use.

Reading Amiga disks

An Amiga disk can be copied to a single file called an ADF, using a program called transdisk supplied with Amiga emulator WinUAE. This file contains a representation of the complete disk, like an ISO file for a CD. An ADF can be used in WinUAE or written back to an actual disk.

The following command reads the disk in DF0:, the internal floppy disk drive, to a file on the ram disk:

If you want to write an ADF to a floppy disk, such as to play a game downloaded from the Internet, use this command to write a diskfile to DF0:

Methods of data transfer

Of the following, I recommend a PCMCIA SD card adaptor if you have an A600 or A1200, using CrossDOS to copy the required drivers over. If you only have Workbench 1.x, use Amiga Explorer.

CrossDOS

Cost: £0

Compatible with: Workbench 2.04 and up

CrossDOS is an Amiga filesystem which allows an Amiga to read PC-formatted floppy disks. It comes with Workbench 2.1 and up, but works with Workbench 2.0. Enter mount pc0: into the command-line to activate.

As the Amiga only has a double density floppy drive as standard, you can only read 720KB formatted disks and not 1.44MB high density formatted disks. A spare Amiga disk formatted on PC is good for this. The 720KB limit causes problems when copying Amiga disk images, which are 880KB. See "Methods of data compression" below for solutions.

There's another guide at l8r.net called How To Use CrossDos On Your Amiga.

PCMCIA SD card/CompactFlash reader

Cost: £10

Compatible with: Amiga 600 / 1200

A PCMCIA CompactFlash or SD card reader is one of the best Amiga peripherals you can buy right now. It's essentially like a floppy drive, but fast, silent, has 1GB+ capacity and compatible with just about everything (including your PC, your camera and mobile phone).

The EDUP MCR-5A PCMCIA SD-card adaptor sells for £4.59 including shipping. It should work on all A600 and A1200s, and I've personally tested it on an A1200 with WB2.1 and a 1GB Corsair 60x SD card. You'll need two drivers from Aminet: cfd.lha to add CompactFlash and SD support, and fat95.lha to support Windows filesystem. You may need to format the card under Windows as "FAT" or FAT16".

Whichever card reader you use, you'll need something else to get the drivers to the Amiga in the first place. You can use CrossDOS as the drivers are only about 200KB. If you don't have a hard disk in the Amiga you'll need to make a Workbench disk with these drivers installed. On the PC side, you can buy a USB to CF/SD adaptor quite cheaply.

Internal IDE CF reader or (2.5" hard disk)

Cost: £10

Compatible with: Any IDE-equipped Amiga (incl. A600 and A1200)

An IDE CompactFlash or SD reader is a cheap, noise-free alternative to an internal hard disk. It has advantages and disadvantages compared to a PCMCIA CF/SD reader.

An IDE to CF adaptor requires no drivers, and consequently can be formatted with the Amiga filesystem used as a boot device like a normal hard disk. It works with Amigas that have IDE but not PCMCIA (A4000, A4000T, expanded Amigas). The drawbacks are that you'll need to open the Amiga to remove the card, and you'll need WinUAE to read the Amiga filesystem. I don't own one of these devices so I can't recommend any particular model.

If you've got a spare 2.5" hard disk kicking around you can put it in the Amiga. It can be connected to a PC using a USB hard disk enclosure and read via WinUAE. For the A600/A1200 you'll probably want a hard disk cradle to make sure it fits in snugly. Remember that Amiga has limits on partition size, and some early A600s are said to have faulty IDE control in ROM. My own 2.5" hard disk is 4GB and has two 2GB partitions.

Serial cable with Amiga Explorer

Cost: £18.20

Compatible with: All Amigas, Workbench 1.2 or higher

Amiga Explorer is a networking solution which uses a null modem cable. It cleverly solves the problem of how to get its own software to the PC side, by sending an installer over the serial cable. The full version is €14.95 from Cloanto.

The drawbacks are that transfers are slow (see "transfer rates", below), you're limited by the length of your cable, and many PCs don't have serial ports any more, requiring a USB to serial adaptor. However, it's the primary option for A500 users without IDE ports. As a bonus, you can run WinUAE and play multiplayer Populous.

ADFRead/Disk2FDI

Cost: £15

Compatible with: Some PCs

ADFRead is a PC program that does the impossible: allows a PC disk drive to read an Amiga disk. Due to the unique way it works, ADFRead requires a PC with two internal floppy drives (not USB floppy drives). It can only read disks, not write, and can only read standard format disks (many games used copy-protected non-standard format).

Disk2FDI is an older program which does something similar.

Ethernet

Cost: £30+

Compatible with: Any PCMCIA/Zorro-equipped Amiga with hard disk and 2MB+ RAM

An Ethernet setup is the most complex and expensive setup listed here. A600/A1200 users can find the EasyNet PCMCIA network card for £30, and big-box Amiga users can expect to fork out a whopping £88.88 for the Zorro-based X-Surf 3CC. You'll then need to copy a lot of software to the PC by some other method, install MUI, setup TCP/IP software, manage connecting this to a Windows network, and setup Windows-style network shares.

On the plus side, this heavy setup will let you hook your Amiga up to the Internet.

Transfer rates

I ran some speed tests using DiskSpeed 4.2 on a stock A1200. Testing with a 262144 byte, MEMF_CHIP, LONG-aligned buffer. Amiga floppy and ramdisk included for comparison.

Serial transfer is limited to around 19.2 kbit/sec on A500/A600 and 57.6 kbit/sec on A1200, for transfer rates no more than 2KB/sec or 7KB/sec. This is slower than CrossDOS floppy, but more convenient.

The Amiga 600/1200 IDE uses PIO Mode 0, which has a limit of 3.3MB/s. You'll actually get less than this on the Amiga as CPU is the limiting factor (this is why earlier Amigas used SCSI). In my test the hard disk transfer used 94%-100% CPU and only reached 1.38MB/sec, and even the ramdisk only reached 1.84MB. This suggests that you're unlikely to exceed 2MB/sec without expensive specialist hardware like an accelerator card.

The PCMCIA SD card device can write a floppy disk image in under two minutes, which is over twenty times faster than the disk drive can read it. This is probably good enough.

Methods of data compression

The main reason you'll want to compress data is if you're using CrossDOS and want to fit an 880KB Amiga disk image onto a 720KB PC disk. It's also useful if your transfer method is very slow or unreliable.

LHA

LHA is the Amiga standard archiver, and can also be read under Windows by WinRAR or 7-Zip. Compress the disk image like so:

There's a snag, however: lha might not reduce the filesize enough to fit on the 720K floppy. The solution is to read or write the file in two parts:

You can concatenate the file in a Windows command prompt:

DMS

DMS, available from Aminet, is an old Amiga program to read Amiga disks to disk images and compress them at the same time. You can uncompress the files back to an ADF file using DMS under WinUAE.

Suppose again that the resulting DMS file is too large. You can split it like so:

You can recombine like so:

As splitting and recombining is a lot of effort, you should try something other than CrossDOS if possible.

Yarr! Pirates!

It's still frowned upon in some circles, but if your original game disks are corrupted or unavailable, you can probably find copies online.

You can, of course, use this to enjoy all the Amiga classics you missed out on back in the day. Strictly speaking this is software piracy, but most classic Amiga games publishers are no longer in business or are disinterested in chasing up copyright on their twenty year old games. See my list of recommended Amiga games.


Page created: 23rd August 2008. Last updated: 16th January 2010