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138 lines
4.5 KiB
Markdown
138 lines
4.5 KiB
Markdown
# Anti-M
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Boot any Apple II disk on any Apple II
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[Download latest Anti-M disk image](https://github.com/a2-4am/anti-m/releases/download/v1.5/anti-m-v1.5-2019-06-11.dsk)
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(version **1.5**, released **2019-06-11**, runs on any 48K Apple II)
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## What is this?
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Many early Apple II games only worked on the original Apple II or Apple ][+.
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They refuse to boot on later models, often displaying an "M" error code. This
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was due to overly aggressive copy protection; late in the boot process, there
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is code that checksums the ROM and reboots if it's not recognized. The games
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themselves would work fine if they were allowed to boot past this ROM check.
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Other games fail on an enhanced Apple //e, due to subtle differences between
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6502 and 65c02 processors. Still others fail on an Apple //c or IIgs, due to
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changes in the boot PROM code. ProDOS fails to boot on clones like Franklin and
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Pravetz. Then there are some _very_ early games that require a 13-sector drive.
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Anti-M uses a modified boot PROM that can boot any disk, then controls the
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game's bootloader long enough to bypass the ROM check and patch any 6502-
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specific opcodes. The result: you can boot any Apple II disk on any Apple II.
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## How do I use it?
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Boot the Anti-M disk. When it prompts you to insert your original disk, do so,
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then press `<RETURN>`. The game should boot normally.
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## Which games are supported?
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- Beer Run (Sirius)
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- Bug Attack (Cavalier)
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- Choplifter (Broderbund) (*)
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- Computer Foosball (Sirius)
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- David's Midnight Magic (Broderbund) (*)
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- Dueling Digits (Broderbund)
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- Eggs-It (Gebelli)
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- Frogger (On-Line Systems) (*)
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- Gamma Goblins (Sirius)
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- Genetic Drift (Broderbund)
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- Hard Hat Mack (Electronic Arts) (*)
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- High Orbit (Gebelli)
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- Horizon V (Gebelli)
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- Jawbreaker ][ (On-Line Systems)
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- Juggler (IDSI)
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- Labyrinth (Broderbund)
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- Lady Tut (Progame)
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- Lazer Silk (Gebelli)
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- Lunar Leepers (On-Line Systems)
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- Neptune (Gebelli)
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- Orbitron (Sirius)
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- Pest Patrol (On-Line Systems)
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- Phaser Fire (Gebelli)
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- Quadrant 6112 (Sensible Software)
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- Red Alert (Broderbund)
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- Russki Duck (Gebelli)
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- Seafox (Broderbund)
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- Serpentine (Broderbund) (*)
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- Sky Blazer (Broderbund)
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- Space Eggs (Sirius)
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- Space Quarks (Broderbund)
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- Star Blazer (Broderbund)
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- Star Thief (Cavalier)
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- Trick Shot (IDSI)
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- Zenith (Gebelli)
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- all 13-sector disks (e.g. Epyx, Edu-Ware, many others)
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- all ProDOS disks
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(*) later re-released with different copy protection. Only the first release
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requires Anti-M.
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## Does Anti-M patch my original disk?
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No! All patches are done in memory only. If you reboot your original disk
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(without running Anti-M), it will fail as usual, because the ROM check or other
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incompatible code is still there.
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## Can I use Anti-M from a hard drive?
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Yes! Copy the `ANTI.M.SYSTEM` file to anywhere on your ProDOS hard drive and
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run it with your favorite launcher. Bonus feature: when launching Anti-M from
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a hard drive, it will skip the prompt and immediately boot slot 6, drive 1.
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## But wait, there's more!
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Anti-M can also boot many games from drive 2, including all the games listed
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above. If you launch Anti-M from slot 6 and it detects a disk in drive 2, it
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will skip the prompt and immediately boot from drive 2. Otherwise, you can
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press `2` at the prompt to boot from drive 2 instead of drive 1.
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To disable auto-boot and show the prompt, even if Anti-M would normally skip
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it, you can press either joystick button (open-apple or closed-apple key) while
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launching Anti-M.
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## History
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v1.5 - 2019-06-11
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- support "Lady Tut"
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v1.4 - 2019-05-24
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- support "Computer Foosball"
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- fix a crash when booting early Spinnaker Software disks (e.g. "Alphabet Zoo,"
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"In Search of The Most Amazing Thing")
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- fix booting ProDOS disks from drive 2
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v1.3 - 2019-04-12
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- support booting from drive 2
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- fix booting on MAME
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v1.2 - 2019-03-24
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- support booting ProDOS on clones
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- additional patches for "Star Thief"
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- launch Anti-M program faster
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v1.1 - 2019-03-16
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- support booting 13-sector disks
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- support booting disks on Apple //c and IIgs which would otherwise time out
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looking for a boot sector (SpiraDisc, some early EA games)
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- bypass a peripheral scan in some games that would hang on some peripherals
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and crash others and require a hardware power cycle in order to reboot
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properly (SpiraDisc)
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- support multiple versions of "David's Midnight Magic"
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- remove "unsupported game" error, always continue booting
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- bypass prompt if launched from hard drive (press the open- or closed-apple
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key on startup to show the prompt)
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- minimum requirements lowered to 48K Apple ][ (still useful for booting
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13-sector disks)
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v1.0 - 2019-03-11
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- initial release
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