Virtual Jaguar v3.4.0 — Peripherals, texture dump, BIOS selection
The peripheral release. Every controller the Jaguar ever had — plus the one
that let you phone your opponent — now works, alongside a texture-dump
pipeline for HD pack authors and user-selectable boot ROMs.
Highlights
Ultra Vortek netplay, over the emulated Jaguar Voice Modem (#481)
The JVM was Atari's voice-and-data modem, and Ultra Vortek was the only
retail title that spoke to it. Both sides of that conversation now work:
the modem's command protocol is emulated on JERRY's UART, and the "phone
call" is carried over the existing netlink transport (TCP or RetroArch
netplay).
Type 911 on the numpad at the Ultra Vortek title screen, one player
dials any number, the other answers.
The protocol was reverse-engineered from the retail ROM rather than
guessed: a custom Phylon command set (not AT), 16-bit words console→modem,
3-byte replies back, and a mutual DTMF probe as the line-quality check. The
full decode is in docs/voice-modem.md.
Verified on two real iOS devices, not only headlessly.
Network link setup that explains itself (#502)
Linking two consoles used to mean typing an IP address — which libretro
core options cannot do. They are strictly enumerated: the frontend stores a
value index, and no core on any platform can present a text field. The
only routes were a .local preset, a file, or localhost, and on iOS those
were the only options at all.
So the link now finds its own peers:
Automatic mode, the new default: if a frontend netplay session is
running, the link rides it with nothing to configure. That path already
worked and nothing said so — it was buried in a blurb on the TCP client
option, findable only once you had already committed to typing an address.
LAN discovery — hosts beacon over UDP and appear in the host picker by
name. Chosen over Bonjour because RetroArch's iOS/tvOS property lists
enumerate only their own service types, so a core advertising its own is
blocked, while the iOS entitlements do permit broadcast. UDP is not the
fallback here; it is the only mechanism that works on the platform this
was reported from.
On-screen narration — what mode resolved, when the link comes up or
drops, how many hosts were found, and a warning when the peer is running a
different device than you (JagLink and Voice Modem cannot interoperate,
and that used to fail silently).
vj_netlink.txt is finally documented: one line, the address only, no
port.
Automatic mode deliberately never opens a listener and never dials a
discovered peer by itself — with the Voice Modem that would place a call the
user did not initiate.
The input-device epic, complete (#428)
Device Notes
ST/Amiga mouse Port 2
Tempest rotary Both ports
Analog / driving TR10 bank-switching protocol
Lightgun Balloons homebrew verified playable
Per-axis tuning Dead zone, offset, response exponent on every analog source
Two of these needed hardware archaeology. The analog controller has no
console-side ADC — Atari deleted it from production silicon, so the
controller carries its own microcontroller and answers the ordinary
$F14000 row scan. The lightgun latches TOM's LPH/LPV light-pen
registers continuously, not on the trigger, which means software cannot
detect a shot from those registers at all — the trigger is an ordinary pad
button.
Texture dump mode (#369)
Every unique blit source a game uses is written out as a PNG with a stable
content hash, ready for pack authors to redraw. The identity contract is
frozen and documented in docs/texture-dump.md:
FNV-1a 64 over format, dimensions and raw source bytes — deliberately not
the palette, because the Jaguar blitter never sees one, and a key the
replacement pipeline cannot discriminate would strand every pack drawn
against it.
Default off. Enable virtualjaguar_texture_dump, play, and find the tiles
under /vj_texdump//.
Texture replacement, tier 1 (#369)
The other half of the pipeline also ships: drop redrawn art into
/vj_texpacks//.png — the same hashes dump mode
writes — and it presents in place of the title's own tiles. Authoring is
"dump, redraw, move one directory over".
Packs are true colour; nothing in the path quantises RGB back to CRY,
and a pack pixel with alpha below 128 keeps the stock pixel instead.
The pipeline never writes the emulated machine. Replacement rides the
existing true-colour shadow framebuffer, gated on a per-pixel
straight-copy witness, so savestates, rewind, run-ahead and netplay stay
bit-identical with or without a pack — a pack cannot desync a link
game or invalidate a state.
Tier 1 covers 16bpp source tiles at 1x through straight-copy blits, which
is the sprite and UI blit class dump mode was built around. Indexed
sources (tier 2) and >1x Stage 2 surfaces (tier 3) are designed but not
implemented; entries of those kinds are skipped and the stock pixel
presents.
Default off, and the option only appears when a pack directory exists for
the loaded cartridge.
Boot ROM selection (#469, #473, #477)
Cartridges can now boot the Series K or Model M console boot ROM
(both embedded), or a custom image from the system directory. External
images are identified by checksum and named in the log — Series K, Model M,
Stubulator '93, Stubulator '94 — with unrecognised images loaded anyway and
flagged, so homebrew and modified ROMs work.
Fixes
Voice Modem corrupted video (#500) — activating the modem tore the
picture apart: scanlines out of order, content stamped repeatedly down the
screen, alternating garbage and clean at 60 Hz. It needed no connection —
starting to dial was enough. UARTRaiseIRQ() asserted a 68000 level-2
interrupt after checking only JERRY's own mask, but JERRY's interrupt
output reaches the 68000 solely through TOM's C_JERENA gate, which both
PIT callbacks apply and the UART did not. Ultra Vortek never enables that
gate (measured: 2598 of 2600 frames), because its DSP polls the serial
status and the 68000 never uses the receive interrupt — so on real silicon
those bytes raise nothing, while here each one re-entered the display
handler at an arbitrary raster position. Measured 3.26 spurious interrupts
per frame before the gate, 0.999 after.
Blitter cross-load state leak (#479) — the B_CMD decode statics were
never reset, so a session that used the fast blitter contaminated the
next session's savestate. Invisible on desktop (a fresh dlopen
re-zeroes statics) and live on iOS, where the core stays resident. Broke
run-ahead and netplay determinism after an engine switch.
CHD session attribution and boot-header search (#476) — two
independent parser bugs. Session metadata was indexed by track number
rather than among itself, mis-attributing session 2 on discs whose first
session has more than one track; and the ATARI boot header was assumed at
a fixed offset when it is really variable mastering filler (2 bytes on one
disc, 378 on another). The second reproduces from CUE and is unrelated to
CHD.
Idle analog offset manufactured input (#439) — a non-zero offset fed
phantom motion every frame from an untouched device, the exact failure the
option exists to prevent.
JaguarDemos BootIntros (#469, #470, #473) — GPU-only jagcrypt carts
crashed the frontend; they now auto-enable the real boot ROM. 46 of 49
demos boot, gated in CI.
Accuracy groundwork
A real-hardware Doom capture was measured against our output: hardware
presents the attract demo at 4.0 fields/flip (15.01 flips/s); we present
2.00. That number now anchors the timing campaign, whose full plan ships in
docs/timing-campaign-plan.md — including
the finding that Doom's own code gates flips on a two-field software floor,
which is why processor-clock scaling never moved the cadence.
The campaign itself lands in v4.0.0.
Known issues
Ultra Vortek netplay is verified over both transports: the direct TCP
link by an automated two-instance test through the in-game lockstep
exchange, and RetroArch netplay by play-testing on two devices. There is
still no automated test for the netplay transport (#494) — RetroArch
netplay cannot be driven by scripted input — so regressions there would
not be caught by CI.
The device-mismatch warning does not fire when the host was selected as
jaghub.local, from vj_netlink.txt, or via VJ_NETLINK_HOST (#501). It
compares against the raw option value rather than the resolved address, so
the warning degrades to silence — connections themselves are unaffected.
Link input latency is authentic rather than good: the modem's DTE rate is
permanently 19200 (proven from Atari's own JVM manual and the retail ROM,
where the connect-speed byte turns out to be cosmetic), which is ~5.8 ms of
wire time each way per frame against a strictly lockstep exchange. An
opt-in enhancement to compress it is tracked as #498 for v3.5.0.
Voice audio over the modem is not emulated (#485) — the real JVM carried
voice modem-to-modem, bypassing the console entirely.
The analog/driving controller implements the TR10 bank-switching protocol
on the $F14000 joystick matrix. No released title is known to read that
protocol, so its verification is the synthetic register-level suite in
test/tools/analog_decode_test.c.
Analog-capable software does exist, but it targets different hardware:
BattleSphere and BattleSphere Gold sample the motherboard 8-bit
ADC at $F17C00 — JERRY GPIO5, the "Paddle Interface", an ADC0844 fitted
only to early Jaguar boards and deleted from production silicon. They round-
robin four channels from a JERRY Timer 1 handler and consume two of them in
an "Analog Joystick Calibrator" screen and in GPU code, gated behind
Gameplay Options → 2nd Controller: Analog Stick. Club Drive writes the
same channel-select without ever reading it back. That interface is not
emulated — we return 0x0000 where an ADC-less console returns 0xFF —
and is tracked separately.
Downloads
Cores for 16 platforms are attached below. No BIOS files are required.
Stats
git diff --shortstat v3.3.0..v3.4.0 — 219 files changed, 98,856
insertions, 761 deletions, across 176 commits.
Maintainers
Joseph Mattiello, with the Virtual Jaguar libretro contributors.
Original Virtual Jaguar by David Raingeard (Potato Emulation) and
James Hammons.
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