Video cards

Which video cards FliperOS supports, and what each one gives on a 15 kHz CRT.

The difference between them is the dotclock: a 320x240 game at 15 kHz needs about 6.5 MHz, a 640x480i boot about 13 MHz. A card that generates those clocks shows each game at its native resolution.

A card that doesn't uses a super resolution: the same lines and the same refresh as the game, with the width multiplied (1280 or 2560 instead of 320). On a CRT the picture is almost the same, since the beam has no horizontal pixels. What gives it away: RetroArch draws its notifications at 2560 wide, so they come out squeezed.

Summary

Card	Driver	Analog output	15 kHz
AMD/ATI Radeon HD 2000 to HD 7000, R7/R9 200 and 300 (GCN 1.0)	radeon or amdgpu	VGA, DVI-I	Native (recommended)
AMD Radeon RX and newer, Ryzen APUs	amdgpu	None on the card; VGA on some motherboards	Native, through an active DisplayPort/HDMI to VGA converter that accepts low clocks
NVIDIA GeForce 8 to GTX 900, Quadro up to K series	nouveau, or NVIDIA's own driver (GTX 900)	VGA, DVI-I	Super resolution; native if the card passes the low resolution test
NVIDIA GTX 10 and newer (Pascal, Turing, Ampere...)	nouveau	None	Super resolution, through a converter
Intel Gen9 (HD/UHD 500 and 600 series: Skylake to Comet Lake)	i915	VGA on the motherboard	Super resolution, with interlace (patch 09)
Other Intel generations	i915	VGA on the motherboard	Super resolution; 480i may not work

Only one card has been seen on a CRT by the project: an AMD R7 240 (radeon). The other lines come from the kernel patches and from what the GroovyArcade and Batocera communities report.

AMD/ATI

The cards CRT_EmuDriver covers on Windows, with VGA or DVI-I: the HD 2000 series to the R7/R9 200 and 300 with GCN 1.0. The 15 kHz kernel patches cover radeon and amdgpu (DCE and DCN 1 to 3): native boot at 640x480iS and every game at its own resolution, in GroovyMAME, RetroArch and the frontends.

Good, cheap choices: HD 5450, HD 6450, HD 7750, R7 240, R7 250.

SI and CIK cards (HD 7000, R7/R9) work on both drivers; the Setup picks radeon by default and offers amdgpu (with Vulkan) in Video Setup > Video driver.

Cards with no analog output (RX 400 and newer) and the Ryzen APUs need an active DisplayPort or HDMI to VGA converter. The card generates the low clocks; whether they reach the tube depends on the converter's chip, so pick one that the GroovyMAME community reports for 15 kHz.

NVIDIA

NVIDIA cards run on the open driver, nouveau, out of the box. On the installed system, Setup > Video Setup > Video driver can switch to NVIDIA's own driver (see below).

With VGA or DVI-I (GeForce 8 to GTX 900, Quadro up to the K series). Out of the box nouveau refuses every mode under 25 MHz. FliperOS's own kernel patch (10_fliperos_nouveau_analog_low_dotclock.patch) lifts that floor on the analog outputs, but whether each card's PLL actually reaches 6.5 MHz varies.

So the card is tested on the tube:

1. boot the NVIDIA 15 kHz entry (super resolution, 1280x480iS);
2. after you confirm the output in the video output test, the Setup shows a Switchres grid at 320x240 for 20 seconds;
3. saw the grid → native resolutions (boot at 640x480iS, dotclock_min 0, RetroArch at native width);
4. black screen or no answer → super resolutions, as before. Nothing is lost by trying.

The test can be repeated on the installed system in Setup > Video Setup > Low resolutions. It only runs on an analog output with a 15 kHz monitor.

Community reports with low clocks on nouveau: GeForce 8400 GS and Quadro K600 (Batocera). No NVIDIA card has been seen on a CRT by the project yet.

Mind the speed: nouveau runs most GTX 600, 700 and 900 cards at their boot clock (it can't raise the clock of Maxwell 2, and on Kepler only by hand). For arcade and 2D consoles that is enough; for PS2, GameCube and Model 3, an AMD card is better, or NVIDIA's own driver.

A user's GTX 980 Ti (DVI-I, VGA-SCART) failed the grid on nouveau, while Batocera showed 320x240 at dotclock_min 0 on the same card. Batocera uses NVIDIA's own driver on those cards, not nouveau. On nouveau the likely limit is the pixel clock PLL: its calculation caps the divider at the VBIOS maximum and doesn't check the oscillator's minimum, so 6.5 MHz gives a black screen with no error. The kernel lines of the grid are saved in the Setup's log (/var/log/fliperos-setup.log) to confirm it.

NVIDIA's own driver. In Setup > Video Setup > Video driver on a card with an NVIDIA chip:

• NVIDIA driver downloads it from Ubuntu's own repository (a few hundred MB), and DKMS compiles its kernel module for the 15 kHz kernel (a few minutes). The package is nvidia-driver-580, from the GTX 900 (Maxwell, the last with DVI-I) to the current cards; it is the one checked to build on the 15 kHz kernel. The 470 of the GTX 600/700 (Kepler) does not build on kernel 6.18, so those cards and the older ones stay on nouveau.
• Both drivers stay installed; the kernel line chooses (modprobe.blacklist=nouveau nvidia-drm.modeset=1 nvidia-drm.fbdev=1, or the NVIDIA modules blacklisted for nouveau). The package's own nouveau blacklist in /lib/modprobe.d is overridden by a file of the same name in /etc/modprobe.d.
• The switch is on trial, like radeon/amdgpu: after the restart, press Enter to confirm the picture. With no answer in 15 s FliperOS goes back to nouveau and restarts. The boot menu (a key during the countdown) also has FliperOS - nouveau driver.
• The low resolution result belongs to a driver, so a switch starts in super resolution. Once the picture is confirmed, the Setup offers the 320x240 grid on the NVIDIA driver.
• X uses the nvidia driver with mode validation relaxed (ModeValidation: modes without EDID, low pixel clocks, any sync range), which a 15 kHz tube needs. RetroArch, Switchres and the console use its KMS (nvidia-drm).
• If a kernel update leaves no NVIDIA module for the new kernel, the boot tries DKMS again; with no module, it goes back to nouveau and restarts, so the screen is never left black.

Not seen on an NVIDIA card yet: the module was built against the FliperOS kernel (580.178.04 on 6.18.54-15khz), but nobody has run it on a CRT.

Without analog output (GTX 10 and newer). Super resolution only, through an active converter. RTX 20 and 30 cards need their GSP firmware, which stays in the system (/usr/lib/firmware/nvidia).

Intel

Intel integrated graphics use the Intel 15 kHz boot entry, always in super resolution (1280x480iS): i915 doesn't generate the low clocks.

On Gen9 (Skylake, Kaby Lake, Coffee Lake, Comet Lake) patch 09 enables interlace, with i915.no_ytiled_scanout=1 on the kernel line. Other generations have no interlace patch: 240p works, 480i may not.

The VGA port of many motherboards is a DisplayPort to VGA bridge chip on the board, so results vary by motherboard.

Several cards

A second card for a second or third monitor works best if it is AMD too. See Multiple monitors.