ADF, IPF, HDF or LHA? Choosing the right format for Amiga emulation

You’ve downloaded an Amiga game, opened your emulator and found four different file formats staring at you: ADF, IPF, HDF and LHA. Each promises a way to run classic Amiga software, but they don’t work in the same way. Pick an ADF and you’re dealing with a virtual floppy disk. Open an HDF and you could have an entire Amiga hard drive ready to boot. LHA brings another approach into the mix, particularly for games running through WHDLoad. The differences matter more than the file extensions suggest. Some formats recreate floppy disks, others package installed software, and certain games need extra emulator support before they’ll run. Here’s how the four formats work, where each fits and what to expect when loading Amiga games on a modern PC.

ADF: The familiar Amiga floppy disk

ADF stands for Amiga Disk File, and it’s probably the format you’ll encounter most often when downloading Amiga games. An ADF file contains an image of an Amiga floppy disk. A standard Amiga floppy holds 880 KiB, and emulators such as WinUAE, FS-UAE and Amiberry can load these images through their virtual floppy drives.

It’s a straightforward setup. Select your ADF, insert it into the emulated drive and start the machine. Games originally released on several disks retain their original loading arrangements, so you’ll occasionally need to swap virtual floppies during play. There’s one catch.

Standard ADF images can’t reproduce every unusual disk structure used by commercial Amiga games. Publishers frequently employed custom disk formats and copy protection, which means many ADF releases contain modified versions of the original software. For conventional floppy-based gaming, ADF offers broad emulator support and a familiar loading process without requiring a hard-drive installation.

IPF: When the original disk structure matters

IPF stands for Interchangeable Preservation Format. It handles something standard ADF images can’t always manage: the unusual disk layouts and protection systems found on original commercial releases.

Rather than storing a conventional floppy image, an IPF file can retain the disk information needed to reproduce custom loading routines and copy protection. For certain games, this makes a practical difference. An original release might fail to start from a conventional ADF image, yet run correctly from an IPF image in a compatible emulator. IPF support isn’t automatic, though.

Some emulator setups require the CAPS image library, and not every emulator supports IPF files. You’ll need to check your configuration before loading one. IPF doesn’t turn a floppy game into a hard-drive installation, either. Multi-disk titles still use virtual floppy drives, and the game follows its original disk-loading routines.

HDF: An entire Amiga hard drive in one file

HDF takes a different approach. Instead of recreating a floppy disk, an HDF file represents an Amiga hard drive. It can contain Workbench, installed games, applications, configuration files and the directories needed to run a complete Amiga system.

This makes HDF useful for emulator setups built around hard-drive installations. You can boot an existing Amiga environment, access installed software and run supported games without inserting individual floppy images.

Some HDF files contain complete Workbench installations. Others provide game-specific setups, including titles prepared for WHDLoad. An HDF isn’t automatically ready for every emulator configuration. The installed operating system, Kickstart ROM requirements, hard-drive settings and software can affect compatibility. It’s a disk image, not a universal game package. An HDF containing a configured Amiga system serves a different purpose from an ADF containing a single floppy release.

LHA: Compressed Amiga software and WHDLoad games

LHA is different again. It’s a compressed archive format, much like ZIP, and Amiga users have employed it for distributing games, applications and utilities for decades. An LHA file doesn’t represent a physical disk. It contains compressed files and directories, which can be extracted into an Amiga-compatible environment.

You’ll encounter LHA frequently in WHDLoad game collections. WHDLoad lets supported Amiga games run from a hard drive, using game-specific installation files and patches to handle loading, disk access and compatibility.

Some emulator front ends can launch supported WHDLoad LHA packages directly. Other setups require you to extract the archive, configure WHDLoad and launch the game from an installed Amiga system.

There’s an important distinction here: not every LHA file contains a WHDLoad game. Plenty contain ordinary Amiga applications, utilities or software archives. The extension tells you how the files are packaged, not necessarily how the contents should run.

ADF, IPF, HDF or LHA: Which format fits your emulator?

Each format serves a different part of Amiga emulation. ADF handles conventional floppy disk images and works with most popular Amiga emulators. IPF accommodates original disk structures and copy protection beyond the capabilities of standard ADF images.

HDF provides a virtual hard drive, suitable for complete Amiga installations and software already configured to run from disk. LHA packages compressed files, including many WHDLoad game releases.

The practical difference comes down to your emulator setup and the software you’re trying to run. A floppy-based game, an original protected release and a WHDLoad installation can require different files and different loading methods.

Check which format your emulator supports, how the game was packaged and whether it needs a floppy drive, hard drive or WHDLoad environment. Once those pieces match, the file extension becomes much less of a mystery.