The core

Why any of this

The Amiga 1200 was the last great Amiga Commodore made, and the desktop people built on it is the one worth having back: Kickstart 3.1, AGA, a hard disk, a graphics card for a screen bigger than the chipset could draw, MUI for modern windows, color icons, and WHDLoad so every game lives on the disk instead of in a box of floppies. An emulator or a MiSTer puts that machine back on your desk. Getting to that finished desktop is the work.

You cannot download it ready-made. Workbench and Kickstart still belong to someone, so the disks and the ROM have to be yours, and Commodore’s own installer has to copy them. Everything after that is a recipe of Proceed buttons, the Green Amiga Alien guide, which people have followed by hand for twenty years. These notes turn that recipe into scripts, so someone new to Amiga emulation gets the upgraded A1200 in an afternoon, from disks they own.

The end of the road is a build nobody babysits. AmiPilot can sit inside the running Amiga, click what is left of the installers, and take a picture of the screen, so an AI agent can check that the desktop came up, that the icons are in color, that a game launches, and fix the script when they are not. Every page here is one step toward that.

The goal is the machine from the install, moved onto the board. Kickstart 3.1 for the A1200, AGA, 2 MB of chip RAM, a Workbench volume the core treats as a real IDE disk, Picasso96 talking to the MiSTer’s own framebuffer, and a WHDLoad drawer you can open without going back to a Windows folder.

People want this because a window on a PC is not the same as a machine on the desk. The MiSTer boots in a second, plugs into the TV, takes a real joystick, and feels like the 1200 did. WinUAE already had the games and a working hardfile, and it is still where the install happens, because your Workbench disks have to be copied by Commodore’s installer somewhere. The MiSTer is where you want to press the button afterwards. The Green Amiga Alien guide still describes the software. It describes it as a tour of WinUAE, and the core has no such window.

The shape we wanted is the one the install describes: not a disk image passed around, but the steps that make one, run in order against a bare volume the way Autopilot or Jamf runs against a new laptop, so the disk on the card is the output of a recipe you can read. On the MiSTer that matters more, because the board cannot show you an installer at all. Everything has to be decided before the file is copied.

The painful part is copying a file the emulator boots and watching Kickstart refuse it.

A WinUAE virtual disk is a file with a filesystem inside and, often, no rigid disk block an IDE controller can read. Minimig, handed that file, invents a block of its own and calls the partition the wrong DOS type. The requester is short: not a DOS disk in device DH0. The other half of the pain is the guide’s habits. It mounts a Programs folder as a second drive. The core mounts hardfiles. It installs a graphics card named uaegfx. That card belongs to WinUAE. On the board the picture stays chipset-sized until the MiSTer monitor is the one in Devs.

An Amiga 1200 and a 1084S showing a Workbench requester: please insert volume Workbench. — The first boot, when the file was still a virtual disk.

Turrican II running on the Minimig core, captured by the MiSTer. — Turrican II on the core, captured by the MiSTer itself. This is the reason for the board.

What comes off your hands

Color icons are one chapter, and the guide offers four ways through it. The script takes NewIcons with ClassAct. Magic Workbench, NewIcons without ClassAct, and the 8-color Iconographics pack are the other three, and stacking them does not add the missing colors. A game icon that says RomIcon is a 16-color dither that turns to noise on this screen; the color picture is the separate .newicon file in that install drawer, and the mint merges it in. Icons drawn on pens 4–7 need two palette files, which is its own note. check_guide_hdf.sh reads the finished hardfile and says which of these files are actually there.

The host writes the disk before the core ever sees it. An empty System volume arrives with Fast File System, international names, and a rigid disk block Minimig accepts, so HDToolBox and Format stay closed. Picasso96’s libraries go on with the MiSTer card, and a leftover uaegfx monitor is removed so ScreenMode is not offering a board this hardware cannot drive. MUI, ClassAct, lha, Installer, and the kickstart images you already own land in the drawers the installers were going to copy. A WHDLoad folder becomes a second hardfile, not bootable, so Workbench still comes up first.

All of that is one command now. build_mister_image.sh takes a Workbench hardfile that boots, in WinUAE or copied back from the board, and never writes to it. It copies the file, swaps uaegfx for the MiSTer monitor, writes the one ScreenMode that draws correct colors through the board’s HDMI, installs MUI, ClassAct, NewIcons, and Scalos with the Backdrop and both palette files, adds lha and Installer, repairs any WHDLoad RomIcons it can find a picture for, runs check_guide_hdf.sh and fails on the first missing file, prints the sha256, and with --ship copies the result to the card. It refuses a name that already exists there, because the core may have that file mounted; the date goes in the name instead.

Several chapters of the guide simply end. There is no JIT to turn off. There is no uaescsi device and no bsdsocket library, so the CD-ROM chapter and the browser’s network chapter have nothing to attach to. The properties window, the Programs directory, and Faster RTG are the same kind of absence: the OSD stores the machine once. A1200, Kickstart 3.1, AGA, 2 MB chip RAM, the system hardfile as primary master, the games hardfile as primary slave, floppies empty. Save that. Reset is the power-on of the core.

export SSHPASS
scripts/build_mister_image.sh --source A1200e-fresh.hdf \
    --out build/mister/A1200e-2026-09-27c.hdf \
    --romicon-newicons /path/WHDLoad_installs --ship
scripts/pack_directory_hdf.sh WHDLoad_usr WHDLoad.hdf WHDLoad
scripts/copy_to_mister.sh WHDLoad.hdf root@mister:/media/fat/games/Amiga/WHDLoad.hdf

# The same chain, one step at a time, for a disk you are building from nothing:
scripts/create_system_hdf.sh Workbench.hdf --megs 64 --name System
scripts/install_picasso96.sh Workbench.hdf Picasso96.lha --mister-rtg MiSTer_RTG.lha
scripts/install_mui.sh Workbench.hdf mui38usr.lha
scripts/install_classact.sh Workbench.hdf classact33.lha
scripts/install_newicons.sh Workbench.hdf NewIcons46.lha
scripts/install_scalos.sh Workbench.hdf Scalos.lha
scripts/install_c_tools.sh Workbench.hdf --lha lha_68020 --installer Installer
scripts/check_guide_hdf.sh Workbench.hdf

If the hardfile already exists and WinUAE boots it, the job is the frame around it: pad it back to the size the filesystem was formatted for, write the rigid disk block, and repair the boot checksum. That repair is the hardfile note. The folder becoming a second disk is the second drive.

Do it in WinUAE, then move the disk

Yes. Those clicks write files, and the files travel with the hardfile. Sit through them once in WinUAE, on the volume you are about to copy. The core then boots a disk that already knows the answers.

The Workbench installer asks for a language, a printer, a keymap, and the six disks. Each answer is a preference or a copy onto DH0. Snapshot stores window positions in the icons. Loading Stuntzi.prefs and saving writes the MUI settings the next boot will use. Scalos is install_scalos.sh: the files, the LoadWB swap, the saved menu, the root window saved as the Backdrop so the first boot is the full desktop, and the two palette files that give MagicWB icons their colors. A game installer that wants the original ADF copies the game onto the hardfile while WinUAE holds that disk. Proceed is still a click, and it happens in that window. After copy_to_mister.sh, the OSD does not need those floppies, and it does not need to see that installer again.

One thing belongs to the board. The OSD is the MiSTer’s own setup, saved once: A1200, Kickstart 3.1, AGA, 2 MB chip RAM, more Fast RAM than you think you need, the system hardfile as master, the games hardfile as slave. ScreenMode used to be the other one. The MiSTer monitor lists its resolutions only while that core is running, so the first disk had its mode saved by hand on the first boot there, and the 24-bit row we picked drew the wrong colors through HDMI. The 16-bit 1280 by 720 row was right, so we saved it once, pulled the 62 bytes back off the board, and the mint writes exactly those bytes now. The check refuses any MiSTer mode deeper than 16 bits. If you arranged the windows on a uaegfx screen of a different size, Snapshot them again after the MiSTer mode is the desktop.

This is also why the proving ground stays in WinUAE. Everything we got wrong on the board, the library in the wrong drawer, the icon that stayed a dither, the drag that made icons vanish, we found by standing in front of the TV. AmiPilot does that looking for us now, but it talks to the host over a serial line the Minimig core does not expose, so the looking happens in the emulator. The order is: change the disk, run verify_winuae_desktop.sh, which restarts WinUAE cleanly and reports whether the Backdrop came up, whether the icons carry their color pictures, and how much color the captured desktop has; open the drawer in question with show_drawer.sh and read what each icon is made of; and only when that passes, mint the MiSTer disk from that source. Two disks have gone to the card this way, each under a dated name, each with its sha256 checked on the board. The MiSTer gets a desktop that has already been seen working, and the one time the board had a different opinion, the 24-bit colors, the fix was read back off the board and vendored, not clicked again.

What has to be on the desk

The scripts arrange files you already have. They run on a machine with Python, xdftool from amitools, and 7z. The board receives the finished hardfiles. The password for that copy stays in SSHPASS.

01A MiSTer with the Minimig AGA core, and a Kickstart 3.1 A1200 ROM already on the card.
02WinUAE, and the six Workbench 3.1 disks, for the one sitting that fills the hardfile. The core boots that finished file. A hardfile copied back from the board works as the source too.
03Picasso96.lha from Aminet, and MiSTer_RTG.lha from the core’s RTG extras. That second archive is the monitor the board can display. fetch_archives.sh archives mister downloads both, and the rest of the freeware below.
04mui38usr.lha, classact33.lha, NewIcons46.lha, and Scalos.lha from Aminet (util/wb, version 1.2b). ClassAct is for the NewIcons prefs window. Scalos replaces Workbench and needs MUI first. lha for the 68020, and Installer.
05The WHDLoad folder, if the games are still a directory from the WinUAE machine, and the install drawers it came from, so --romicon-newicons can find the color pictures. Any kickstart images you already own for slaves that ask for one by name.

The scripts live in amiga-utils.

Step by step: the MiSTer ledger. The WinUAE afternoon is the install. The recipe both of them follow is the Green Amiga Alien guide.