_{Logo © Andy Taylor (MW0MWZ)}

UltraViolet

An open-source emulator for Sun UltraSPARC workstations, starting with the Ultra 5 and Ultra 10: the sun4u (sparc64) platform's UltraSPARC IIi processor with its on-chip memory controller and PCI host bridge, the PCI I/O chipset, onboard ATI Rage graphics and, on the Ultra 10, the UPA slot. The aim is to run the original OpenBoot PROM and Solaris unmodified, at or above the speed of the real machine, with a just-in-time compiler for the UltraSPARC IIi. It runs on Linux, macOS and Windows.

_{Solaris 8 and CDE on the Ultra 10 with a Creator3D in the UPA slot}

OpenBoot 3.31	CDE on the onboard Rage Pro	Machine settings

Status

UltraViolet runs the original OpenBoot PROM and real operating systems, installed from their own media.

• Machine: OpenBoot 3.31 runs its power-on sequence and boots from disk, CD-ROM or the network, with the screen and keyboard or the serial port (ttya) as its console. Modelled: the UltraSPARC IIi's PCI bus module (Sabre) with its IOMMU and interrupt mapping, the Advanced PCI Bridge (Simba), the PCIO EBus with the flash PROM, the M48T59 NVRAM and clock, the SuperIO's keyboard and mouse UARTs and floppy controller, the SAB82532 serial ports, the CMD646 IDE controller with ATA disks and an ATAPI CD-ROM drive, the on-board Happy Meal Ethernet, the on-board ATI Rage Pro graphics with its drawing engine, the CS4231 audio codec, the front-panel power button, and a Sun Type 5 keyboard and mouse. The screen comes up at the resolution chosen in the settings (--resolution: 640 x 480 to 1600 x 1200 on the Rage Pro), on a monitor that answers DDC with its EDID.
• Creator3D: a Creator3D (FFB2+) in the Ultra 10's UPA slot, with UltraViolet's own open source FCode for it built in (firmware/creator3d), or Sun's FCode read from a real card (see Firmware and media), at resolutions up to 1920 x 1200: OpenBoot takes it as its screen, with the FCode's banner logo; Solaris 8 and 9 run the CDE desktop on it and Solaris 10 its GNOME desktop, and NetBSD, OpenBSD and Linux their consoles. Its 2D drawing, window lookups, overlay and vertical retrace interrupt are modelled; its 3D operations are not yet.
• Guests: Solaris 8, 9 and 10 install from their media; Solaris 8 and 9 run the CDE desktop on the Rage Pro, and Solaris 10 its GNOME desktop in 24-bit colour. NetBSD/sparc64 (8.1 and 11.0), OpenBSD/sparc64 8.0 and Debian GNU/Linux 9 (sparc64, Linux 4.15) install to disk and boot to a login, with networking; OpenBSD runs X on the Rage Pro.
• Processor: the SPARC V9 integer unit with register windows, trap levels and the global register sets, the I- and D-MMU with their TLBs and TSB pointers, the internal ASIs, TICK and interrupts, the floating-point unit and VIS 1.0; decoded blocks are cached, and blocks run often are compiled to x86-64 or AArch64 code. Guest time keeps to the wall clock.
• Front end: a window with the machine's screen, its keyboard, mouse and sound on the host, menus and settings, and terminal windows for the serial ports; or headless, with ttya on the terminal. It builds on Linux, macOS and Windows.

Not done yet: the Creator3D's 3D operations, audio capture, audio CDs, and the Blade 100/150 and Blade 1000/2000 machines. See docs/ARCHITECTURE.md for how it is put together.

Performance

The same NetBSD/sparc64 8.1 disk image run under UltraViolet and under QEMU 10.0's sun4u machine, both with 256 MB of memory, on the same host each time. UltraViolet ran with its default settings (guest time kept to the wall clock, disks at the host's speed). Each figure is the median of three runs, in seconds; lower is better. The last column is UltraViolet's speed as a multiple of QEMU's: above 1x is faster, below 1x slower.

x86-64 (2 cores)

Test	What it does	QEMU 10.0	UltraViolet	Relative to QEMU
Process start	300 runs of /bin/echo from the shell	3.58	2.58	1.39x
awk	a 2-million-step integer loop	17.09	7.64	2.24x
gzip	gzip -6 of the kernel (10 MB)	2.89	3.06	0.94x
md5	md5 of the kernel, three times	1.55	0.86	1.80x
sort	sort the word list, forwards and in reverse	2.41	1.31	1.84x
C compile	cc -O2 of a 100-function source file	18.89	12.33	1.53x
FP matrix	160 x 160 double-precision matrix multiply, 20 times	2.08	1.24	1.68x
FP library	2 million rounds of sin, cos and sqrt	3.37	2.01	1.68x
Page faults	touch every page of 32 MB, 8 times	2.00	1.44	1.39x
memcpy	8 MB copies, 120 times	2.41	0.55	4.38x
Large fork	300 forks of a 32 MB process	2.76	1.87	1.48x
Disk write	64 MB written with dd, then sync	1.28	0.85	1.51x
Disk read	128 MB read from the raw disk with dd	1.47	0.87	1.69x
tar	/usr/include copied with tar, then sync	10.28	5.57	1.85x
sleep	sleep 10	10.01	10.00	1.00x

Apple M4 (arm64 Linux)

Test	QEMU 10.0	UltraViolet	Relative to QEMU
Process start	1.87	0.90	2.08x
awk	11.86	3.06	3.88x
gzip	2.08	1.90	1.09x
md5	1.05	0.40	2.63x
sort	1.61	0.59	2.73x
C compile	9.44	6.47	1.46x
FP matrix	1.28	0.64	2.00x
memcpy	1.45	0.45	3.22x

UltraViolet is faster than QEMU in every timed test on the M4 (sleep only checks the clock), and in all but one on the x86-64 host: gzip, which takes about 6% longer there. Its time goes on short loops of translated code, most of it on the loads of the data being compressed, each waiting on the one before.

Both kept the guest's clock to the wall clock, to within a second over each whole run. With Fast disk turned off in the settings (the disks at an Ultra 10's own speed), on the x86-64 host the disk write takes 4.1 s, the read 8.5 s and tar 10.4 s; the other figures do not change.

Downloads

Ready-built programs are on the releases page. None of them include firmware or operating system media: see Firmware and media.

• Linux (x86-64 and arm64): an AppImage, for Ubuntu 22.04, Debian 12 or any distribution as new. Make it executable (chmod +x) and run it.
• Windows (x64): a zip. Unpack it and run ultraviolet.exe.
• macOS (15 or later, Apple silicon or Intel): a disk image. Open it and drag UltraViolet.app to Applications. It is not notarized, so before opening it the first time, clear the download mark: xattr -dr com.apple.quarantine /Applications/UltraViolet.app.

Building

You need:

• CMake 3.21 or later, Ninja (or make) and pkg-config;
• a C++20 compiler: GCC 12 or later, or Clang 15 or later;
• SDL3 for the display window, keyboard and mouse. Without it the emulator still builds, but runs on the serial console (ttya) only (CMake warns when it cannot find SDL3);
• libslirp for user-mode networking (--net user). Without it only --net tap:NAME is available.

On Debian 13 or Ubuntu 25.04 and later (including 26.04 LTS):

sudo apt install build-essential cmake ninja-build pkg-config libsdl3-dev libslirp-dev

On Fedora:

sudo dnf install gcc-c++ cmake ninja-build pkgconf-pkg-config SDL3-devel libslirp-devel

On macOS (Apple silicon or Intel), with the Xcode command-line tools for the compiler and Homebrew for the rest:

xcode-select --install
brew install cmake ninja pkgconf sdl3 libslirp

On Windows, with MSYS2: in its UCRT64 shell,

pacman -S mingw-w64-ucrt-x86_64-gcc mingw-w64-ucrt-x86_64-cmake mingw-w64-ucrt-x86_64-ninja \
          mingw-w64-ucrt-x86_64-pkgconf mingw-w64-ucrt-x86_64-sdl3 mingw-w64-ucrt-x86_64-libslirp

TAP networking is Linux-only; user-mode networking works everywhere.

Ubuntu 24.04 LTS and older releases do not package SDL3; build and install it from source first (SDL's build instructions), or build without it for the serial console only. Distribution SDL3 packages support both Wayland and X11 desktops; an SDL3 built from source needs the Wayland and X11 development headers installed beforehand to support them.

Then, on every system, configure and build (the first command makes the build folder; run it again after installing a missing library):

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
ctest --test-dir build      # unit tests

Check the configure output: it says if SDL3 or libslirp was not found.

On macOS the build makes build/UltraViolet.app, a normal application with the menus in the system menu bar (build/ultraviolet links to the program inside it, for running from the terminal). Once it is built, to make a copy that runs on its own, with the libraries it uses copied in and signed for this Mac, in the Applications folder:

cmake --install build --prefix /Applications

No sudo is needed: an administrator account can write to /Applications. (The install_name_tool warnings about invalidated signatures are expected: the copy is signed again as the last step.)

On Windows, build/ultraviolet.exe runs from the MSYS2 shell; to run it elsewhere, copy the DLLs it uses from /ucrt64/bin next to it.

Running

./build/ultraviolet

opens the window with the machine off and the settings from last time (Machine > Settings: processor clock, memory, console, keyboard layout, the PROM folder, NVRAM, hard disk and CD-ROM images, network, timing). The settings, a log and folders for ROMs, disk images and NVRAM are kept in an UltraViolet folder in the user's Documents folder. The flash PROM is UltraViolet's own OpenBoot, built in; Machine > Settings (Flash PROM) or --prom supplied takes the newest Ultra 5/10 image in the PROM folder instead (roms beside the program, else the UltraViolet folder's roms), such as Sun's OpenBoot 3.31.

Given a machine on the command line it powers on at once:

./build/ultraviolet --nvram disks/ultra10.nvram \
    --disk disks/ultra10.img --disk-size 8192 --cdrom iso/solaris.iso

At power-on the window is sized for the screen's resolution (Settings, Resolution), shrunk to fit the desktop if need be; it can be resized freely after that. The status bar's Turbo button lifts the speed limit while the guest's clocks still follow the host's, so it keeps real time; Settings, Performance, Turbo on at boot powers on with it on.

The machine's screen is in the window, with the host's keyboard and mouse as its Sun keyboard and mouse: click the screen to give it the mouse, Ctrl+Alt+G (Ctrl+Option+G on a Mac) to take it back (opening Settings takes it back too); Ctrl+Alt+A sends Stop-A, Ctrl+Alt+E changes to the next CD in the set, Ctrl+Alt+F switches to full screen. The Machine menu also has the front-panel power button, the Sun keys a PC keyboard lacks (Stop, Again, Props and the rest), powering on with keys held (Stop, Stop-D, Stop-F, Stop-N), and unplugging the keyboard. The machine's audio, and the keyboard's bell and clicks, play on the host (Settings, Sound). The serial ports have terminal windows (View menu), where Pause or Ctrl+Shift+B sends a BREAK. With --console ttya there is no keyboard, and OpenBoot and Solaris use ttya as the console (Ctrl+Alt+A then sends a BREAK). --headless runs without a window, ttya on the terminal (Ctrl-] then q quits; ~# at the start of a line sends a BREAK). --disk is a raw image on the primary IDE channel (created at --disk-size megabytes if it does not exist); --cdrom is an ISO image in the CD-ROM drive (given more than once, a set of discs). --help lists the rest.

The Ethernet is on user-mode networking by default when built with libslirp (--net user; --hostfwd tcp:2222:22 forwards a host port to the guest), or on a TAP interface (--net tap:NAME, Linux), or unplugged (--net none). --mac sets the Ethernet address of a new NVRAM.

On user-mode networking the guest is behind a NAT, and DHCP gives it:

Address	10.0.2.15, netmask 255.255.255.0
Host name	UltraViolet
Domain	home.arpa (the domain reserved for local networks)
Gateway	10.0.2.2 (the host)
DNS server	10.0.2.3

These are fixed: each machine has a NAT of its own, so nothing else on that network can clash with them. The DNS server answers the guest's own name, and its address back to that name, in any domain: the one DHCP gives, or whatever domain an installer is given, so a name-service check during an install succeeds. A name the guest asks DHCP for is answered the same way, and so is an address query for no name at all, which is how the Solaris installer looks up its own name before it has set the one DHCP gave it. Other names go to the host's resolver.

Firmware and media

UltraViolet runs OpenBoot, with Solaris (or another sparc64 operating system) from its media. Its own OpenBoot is included and built in by default: open source, built from Sun's OpenBoot 4.23.0 release for the Ultra 5 and 10 (firmware/openboot). It is still being completed (Solaris 8, 9 and 10 boot with it, from their installation media and from disk; it has OpenBoot 3.x's selftests and diagnostic commands, but no power-on selftest yet); the Ultra 5/10's own Sun OpenBoot (3.31) is chosen under Settings (Flash PROM) or with --prom supplied. Sun's images and the operating systems are not included: roms/README.md says which images UltraViolet expects, where they come from, and how to make them from the original Sun files with the sunrom tool. The roms/, iso/ and disks/ folders are ignored by git (but for that page).

For the Creator3D, open source FCode is included: UltraViolet's own (firmware/creator3d), built into the program and used by default, so the card needs no Sun firmware. If you have a real Creator3D, you can read its own Sun FCode from the card's PROM in a running Solaris system and use that instead: tools/sunrom/README.md says how, and roms/README.md what the image should be. Put the image in the PROM folder, then choose it under Settings (FCode) or with --creator3d-fcode supplied.

Legal

Copyright (C) 2026 Andy Taylor (MW0MWZ).

UltraViolet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. See LICENSE.

The FCode in firmware/creator3d (the Creator3D's) and firmware/rage (the Rage Pro's) is under the MIT licence; see their LICENSE files (Creator3D, Rage Pro).

OpenBoot in firmware/openboot is Sun Microsystems' release of OpenBoot 4.23.0 under Sun's BSD-style licence, with UltraViolet's additions under the same terms; see its LICENSE.

The logos, UltraViolet's (in graphics) and those of the two FCode programs (in firmware/creator3d and firmware/rage), are © Andy Taylor (MW0MWZ), all rights reserved: neither licence covers them.

Sun, Ultra, Solaris and OpenBoot are trademarks of Oracle and/or its affiliates. SPARC and UltraSPARC are trademarks of SPARC International, Inc. ATI and Rage are trademarks of Advanced Micro Devices, Inc. UltraViolet is not affiliated with or endorsed by any of them.