Create README.md

README.md

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+# Anti-M
+
+Boot ROM-limited games on any Apple II.
+
+## What is this?
+
+Many early Apple II games only worked on the original Apple II or Apple ][+.
+They refuse to boot on later models, often displaying an "M" error code. This
+was due to overly aggressive copy protection; late in the boot process, there is
+code that checksums the ROM and reboots if it's not recognized. The games
+themselves would work fine if they were allowed to boot past this ROM check.
+
+Anti-M is a pre-booter that controls the games' bootloader long enough to bypass
+the ROM check, allowing you to play these games on any Apple II.
+
+## How do I use it?
+
+Boot the Anti-M disk. When it prompts you to insert your original disk, do so,
+then press `<RETURN>`. The game should boot normally.
+
+## Which games are supported?
+
+Gebelli Software:
+
+- Eggs-It
+- Horizon V
+- High Orbit
+- Lazer Silk
+- Neptune
+- Phaser Fire
+- Russki Duck
+- Zenith
+
+Broderbund Software:
+
+- Choplifter (*)
+- Dueling Digits
+- Labyrinth
+- Seafox
+- Serpentine (*)
+- Sky Blazer
+- Star Blazer
+
+(*) later re-released with different copy protection. Only the first release
+requires Anti-M.
+
+## Does Anti-M patch my original disk?
+
+No! All patches are done in memory only. If you reboot your original disk
+(without running Anti-M), it will fail as usual, because the ROM check is still
+there.
+
+## Can I use Anti-M from a hard drive?
+
+Yes! Copy the `ANTI.M.SYSTEM` file to anywhere on your ProDOS hard drive and run
+it with your favorite launcher.
+
+## History
+
+2019-03-09
+
+- initial release