The Action Replay III was Datel's freezer cartridge for the Amiga — plug it into the expansion port, hit the button mid-game, and you could inspect memory, poke cheats, rip music and sprites, or save a snapshot. Working originals are now scarce and expensive, and the custom logic inside them was never documented.

This is a complete reverse-engineered replica. The original PAL16L8 chips were read out on an ALL-11 programmer and their logic decompiled into equations, then re-implemented as GAL16V8 fuse maps; the two 1 Mbit ROM images and all five PLD files are included, so a built board is functional rather than a display piece. The design is a 114 × 96 mm two-layer KiCad 8 project with an 86-pin card-edge connector, five GALs, 64 K and 256 K SRAM, a 555 timer and a freeze button.

Two mutually exclusive variants are provided: one using PLCC-32 one-time-programmable EPROMs, and one using DIP-32 UV-erasable EPROMs in sockets. The DIP version is the more forgiving build. Most surface-mount footprints are hand-solder variants with extended pads, and roughly a third of the parts are through-hole, so this is a design intended for hand assembly — though the SMD subset can be machine-placed using the included centroid files.

This is simply a share of an existing open-source project, not my own work. All design credit belongs to na103, with footprint contributions from mthiesen, and the optional 3D-printed case is a separate work by fongo2k on Printables. The original repository is at https://github.com/na103/ar3 — please go there for the canonical source, and consider supporting the author via the ko-fi link in the upstream README.

Note that the repository's licensing is ambiguous: the README states CC BY 4.0 while the LICENSE file states CC BY-NC-SA 4.0. Building for personal use is fine under either, but check with the author before doing anything commercial.