Using lr-puae for Amiga emulation

lr-puae has been updated quite a bit since the docs that were on the RetroPie site. I’ve updated the docs with the latest from the github. The big things that have changed since the original docs were written are:

• the core used to only support .uae files that pointed at .adf files. This is no longer true. It now loads all of these: .zip .uae .adf .dms .fdi .ipf .hdf .hdz .m3u
• the core has WHDLoad support now. This requires games in .hdf or .hdz format. It does not support the .lha files used by Amiberry. (This is no longer true; the latest versions of lr-puae support .lha files.) See the next reply for a script that can convert .lha files for use in lr-puae.
• there are special steps required for supporting .ipf disk images.
• the core supports autoselection of machine configs by adjusting the ROM filename.

Why use lr-puae instead of Amiberry? It is definitely less plug n play. Mostly only if you want to use Retroarch features beyond the controls: shaders, overlays, etc. It also seems to support a few more file types, though I suspect that the docs are incorrect on Amiberry only supporting .lha (I’d be surprised if it didn’t support .adf and .hdf).

Some of my learnings which may help others are below. I’ve merged much of this into the RetroPie docs already.

ROM formats

By far the commonest file formats you will find are .adf and .lha.

One thing that Amiga enthusiasts seem to point out repeatedly is that although you may be able to expand an .lha file on Windows, you often shouldn’t; the Amiga operating system and Windows don’t always agree on paths and special characters, with the result that you can corrupt the file when unzipping it.

How lr-puae loads things

1. The Retroarch config file sets the machine specs.
2. A game override may change the machine specs.
3. You select a rom.
4. If the file is a .m3u, the core then proceeds to parse it and see what the first rom in line is. Otherwise, it looks at the file directly.
5. If the file isn’t a .uae file, the core automatically generates a file called puae_libretro.uae in your /roms/amiga directory with the config set to match the machine specs from Retroarch. Otherwise, your rom IS a .uae file with config specs.
6. The core loads the .uae file and boots the emulator to match. This sets machine specs which may override Retroarch!
7. If what the .uae file points at happens to be a hard disk image, the core loads ~/RetroPie/BIOS/WHDLoad.hdf, then attaches the second hard disk image, looks at it, decides what machine settings it needs (thereby possibly changing the machine specs again), and boots from the first hard disk image.
8. Hopefully the game runs.

Using .ADFs

.adf files can be placed directly in your /roms/amiga folder. They can be loaded directly, but there are many possible configurations for the emulated Amiga. If you follow the standard setup instructions, you will have three Kickstart BIOS roms in your ~/RetroPie/BIOS folder with the correct names. Retroarch will then support three presets, one each for Amiga 500, Amiga 600, and Amiga 1200. These will have several variables preconfigured selected for maximum compatibility. It does not mean that one of these three configs will run every game.

The other thing to note is that one of the other Retroarch options is floppy speed. It can run between 100% and 800% speed. Needless to say, this is a potentially nice speed-up in loading times, but some ROMs will not work unless they are at 100% speed because of copy-protection.

Try the .adf, and if it doesn’t work, enter the Retroarch GUI and try out the next machine. You will have to exit Retroarch and relaunch the game to see if it works. If it does, you have two choices:

• save a game override using the Retroarch Options menu
• modify the ROM file name by adding a substring:
  “(A500)” or “(OCS)” to use an Amiga 500 model.
  “(A600)” or “(ECS)” to use an Amiga 600 model.
  “(A1200)” or “(AGA)” to use an Amiga 1200 model.

Either way should result in generating puae_libretro.uae with the specific settings. Note that a game override is a bit more flexible since you can save not only machine type, but floppy speed and other settings per game. The substring method will only change the machine type and automatic settings associated with it.

Using .IPFs

There is additional setup required to use a .ipf disk image. I have copied over the instructions given on the github for the core to the RetroPie docs, and compiled the latest version, but have not succeeded in getting it to work on a Pi. According to the changelogs, this feature was only tested on Windows.

Using WHDLoad games

Take it as a given that you need to create ~/RetroPie/BIOS/WHDLoad.hdf per the instructions in the RetroPie docs.

Next, a lot of advice on the Net says to set your machine to be an Amiga 1200. The boot image on the WHDLoad.hdf apparently will adjust downwards if the game requires it. That said, an Amiga 1200 has twice the CPU speed of the earlier machines, making it that much more intensive to emulate; I was able to run Agony on an emulated A600 and buy a couple of frames.

The vast majority of WHDLoad format games out there are in .lha format for Amiberry, not in .hdf format. These will not load.

There are many that are in .zip format and just have the contents of an .hdf file, rather than being an .hdf.

On top of that, some .hdf files are not set up for WHDLoad. And others are, but won’t load in lr-puae because of the directory structure. Many files out there have a directory structure that looks like this:

Agony (1992)(Psygnosis).hdf
  Agony.info
  Agony (folder)
    Agony.info
    Disk.1
    Disk.2
    Disk.3
    Agony.slave
    Manual
    Manual.info
    ReadMe
    ReadMe.info
    scores.sav

This will not work in lr-puae. To fix this by hand, you can use ADF Opus to create an HDF file that looks like this:

Agony (1992)(Psygnosis).hdf
    Agony.info
    Disk.1
    Disk.2
    Disk.3
    game.slave
    Manual
    Manual.info
    ReadMe
    ReadMe.info
    scores.sav

The two big changes:

1. There isn’t a folder at the top level. If your .slave file isn’t at the top level of the .hdf, you will get a DOS window popup stating “DOS Error #205 (object not found) on reading ‘.slave'”.
2. Instead of <gamename>.slave, that file must be named game.slave. It doesn’t matter (despite what you may see on the net) whether it’s .Slave or .slave, based on my testing.

The next reply has a link to scripts that will fix HDFs, convert LHAs, and set up ZIPs so that they all work in lr-puae.

WHDLoad files have two advantages over .adf files:

1. They have generally been configured in advance to have the right machine settings. There’s a large Amiga community building WHDLoad files with the right specs.
2. They load way faster.

One big difference from Amiberry is that lr-puae does not use an XML file and a network connection to validate or checksum WHDLoad files against a central game database.

Video and performance

To simplify things, I have set the Retroarch settings to PAL, overscan cropping false, and high resolution (most games are low resolution, but will automatically get line-doubled by the emu). I also run a lower res than I usually do, to reduce load.

If you get audio crackle, try setting your screen to a 50Hz refresh rate via the Runcommand menu, and make sure that it’s also set that way in Retroarch.

The Retroarch “CPU compatible” option improved performance even when my machine was set to emulate an Amiga 1200. It’s not supposed to; it’s supposed to only work when emulating a 68000 chip, and the 1200 had a 68EC020. Some games will not work with “CPU Compatible” set to false, but I have it set this way as the default for now.

I’ll keep exploring performance options; so far, I’ve doubled framerate in my test game (Agony, which is high-res and seems demanding, compared to my other test game, Archon).

I’ll also document what the Retroarch options do, based on the configuration.txt file in the github; I think most people won’t dig that deep to learn what options do.

Retroarch configs

sudo apt-get update
sudo apt-get install python-pip
sudo pip install amitools
sudo apt-get install -y lhasa
apt-get install zip unzip

sudo chmod a+x amigatool*
sudo chown pi:pi amigatool*

Usage

./amigatool.sh filename

./amigatool-batch.sh

Batch processing 13 for conversion to lr-puae .hdf roms.
0/13 Agony (1992)(Psygnosis).hdf: extracting....unpacking...processing.......This file does not contain a WHDLoad game.
1/13 Agony_v1.3_0960.zip: extracting.....found game Agony...packing..........copying to /hdf...  Done!
2/13 Agony_v2.0_NTSC_2701.lha: extracting.....found game AgonyNTSC...packing..........copying to /hdf...  Done!
3/13 Alien Breed WHDLoad v2.3a.hdf: extracting....unpacking...copying to /hdf... Done!
4/13 Alien Breed WHDLoad v2.3a.zip: extracting....unpacking...processing.............packing...copying to /hdf...  Done!
5/13 Aliex_v1.1.lha: extracting.....found game Aliex...packing.....copying to /hdf...  Done!
6/13 amigatool-batch.sh isn't a .zip, .lha, or .hdf.
7/13 amigatool.sh isn't a .zip, .lha, or .hdf.
8/13 Archon2_v1.1_0905.hdf: extracting....unpacking...processing......packing...copying to /hdf...  Done!
9/13 Archon2_v1.1_0905.lha: extracting.....found game Archon2...packing.......copying to /hdf...  Done!
10/13 Archon_v1.2_NTSC_0914.lha: extracting.....found game ArchonNTSC...packing.......copying to /hdf...  Done!
11/13 Skipping directory blankhdfs.
12/13 Skipping directory hdf.