RetroRecomp v0.19.0 — more native 16-bit execution and refined scanlines

RetroRecomp v0.19.0 — more native 16-bit execution and refined scanlines

Mega Drive

Sonic the Hedgehog now uses the same instruction-AOT path as Columns,
Golden Axe and Castle of Illusion, preserving the real 68000 PC, stack and
interrupt frames. The earlier Sonic-specific callbacks are no longer used
on this path. After learning four missing ROM entries, demo and scripted-play
checks of 3,600 frames each completed with zero interpreted main-CPU opcodes.
Their complete visible-frame sequences and final CPU, memory and VDP state
match the internal reference. Golden Axe also passes the same full-length
regression check. The sound Z80 remains interpreted.

Super Nintendo

Super Mario World now has a compiled 65816 operation map for every physical
ROM byte, with live LoROM mapping, real PC/stack control flow, timed operand
reads and register-width handling. Conversion tests learn RAM helpers in
a library scoped to the exact cartridge hash; each native helper verifies
its PC and four live bytes before running. Modified or unknown code keeps
the reported fallback. Games never write this learning library themselves.

The first ROM-only pass reported 372,060 interpreted instructions in demo and
100,750 in play. Learning 130 RAM variants reduced both to zero over the next
two 3,600-frame checks, about 49 million retired instructions per scenario.
Visible-frame sequences, final CPU/memory state and CPU/master/APU clocks
match the internal reference. The earlier reference divergence is resolved
on these tested paths. Authored fixtures pass 16,544 instruction/state/bus
comparisons, including register widths and changed-code guards.
The SPC700 sound processor remains interpreted.

Scanlines and validation

Mega Drive and SNES scanlines now draw a fine translucent gap for each guest
raster row instead of darkening every other game row. A cached mask follows
the actual display height, including fractional fullscreen scaling and HiDPI;
below 2x, the effect stays off to preserve readability. Framebuffers and guest
timing are unchanged. Numeric presentation checks pass, and both compressed
test exports launch with the filter active without creating files or folders.

Both 16-bit converters compare native and reference execution over the full
requested demo/play length. Missing diagnostics or differences reject the
candidate and preserve the previous export. The memory command also reports
the MD/SNES converter's ROM entries, guarded RAM variants and library size.
162 ROM-free Python tests pass. Native/reference agreement uses shared engine
semantics; independent hardware fidelity, complete gameplay and physical
latency remain separate evidence.

Scope and update

Mega Drive and SNES remain experimental. Compatibility is still restricted
to the four exact qualified NTSC Mega Drive revisions and the qualified USA
revision of Super Mario World. Other games, PAL execution and F8/F9 states
are not enabled for these profiles; SNES cartridge-save persistence is also
unfinished. SNES conversion needs installed stable Rust >= 1.85.
See qualified cartridges and evidence.

Download the single Windows x64 Retro-Recomp.exe, or use Check for updates.
Regenerate games to receive the new execution paths and scanlines; updating
the converter preserves existing game exports and settings. No ROMs, downloaded
covers, generated games, settings or personal compilation library are bundled.
Component terms and notices remain in the EXE, including the imported
frameworks' PolyForm Noncommercial licences. The matching
UPX 5.2.1 source archive remains in the repository.