Overview
An ARM64 JIT-focused fork of Previous, the NeXT Computer emulator. Doing for Previous what macemu-jit did for Basilisk II and SheepShaver: bring over a newer AArch64-capable JIT toolchain, connect it to the emulator, and compare its behaviour with the interpreter.
How it works
The fork brings the uae_cpu_2026 JIT/compiler into Previous through a bridge in the CPU loop. It translates emulated instructions to native ARM64 code, while retaining the interpreter for comparison.
Opcode comparisons and headless boot tests check the new path. The JIT remains behind an experimental build flag so the upstream interpreter can still be used.
Features
Transplanted JIT runtime
uae_cpu_2026 vendored; bridge and runtime scaffolding complete.
Opcode equivalence tests
Interpreter vs JIT comparison across risky and missing opcode families.
Headless boot tests
Checks guest startup without requiring an interactive display.
Full NeXT hardware emulation
Original 68030 Cube, NeXTcube/station variants, NeXTdimension board.
Experimental build flag
-DENABLE_EXPERIMENTAL_UAE2026_JIT=ON — keeps upstream usable in parallel.
Architecture
Posts
2026-05-10
Notes for May 3-10
2026-05-03
Notes for April 27 – May 3