Change display mode?

How can I change the display mode? I need:

MODE 13 (320 × 256 8bpp)

or

MODE 49 (320 × 480 8bpp)

Is there a config file to add new modes?

Micky

If it’s a Raspberry Pi you’re using, then you’ll need AnyMode: http://www.pi-star.co.uk/anymode/

To expand on what Steve said…

Those modes are below the minimum bandwidth/clock spec for an HDMI connection (roughly 640×480 although you can creep lower). To use them you need some form of upscale system. RISC OS doesn’t have built-in upscaling, so realistically you’d need either an emulator or to use the Pi’s hardware upscaler, which is what Anymode does.

To use the Pi hardware upscaler, you need to disable the default setting for RISC OS on the Pi which is to handle mode-changes directly. Instead the Pi needs to be configured to auto-scale everything to the detected monitor’s EDID default mode. Note that this can sometimes fail with certain monitors (my test display is mis-identified, for example). To do this, you do so by adding disable_mode_changes to the first line of the cmdline.txt file in !Boot.Loader (create the file if it does not already exist).

Note this is also possible via a tick box in !PiTools but obviously the DIY method is easy and described above.

I don’t think you need to add MDF (monitor definition file) entries for numbered modes when using AnyMode, but I could be wrong.

I did not know this. Ok, HDMI goes down to max. 640 × 480. And what is with games like Wolfenstein 3D? It uses:

MODE 13 (320 × 256 8bpp)
or
MODE 49 (320 × 480 8bpp)

Not playlable?

Micky

What is with those games is they were written in the 1990s.

Wolfenstein 3D is on the list of games that work using ADFFS

Wolfenstein 3D is on the list of games that work using ADFFS

I think the operative, and critical, part of that sentence is “using ADFFS”
i.e. download ADFFS, setup as per instructions, use, do not attempt to do anything other than follow those instructions.

Which should be the first way to try playing old games.

Thanks for your tips!

I install ADFFS and start it. Then I start Wolfenstein 3d. Ups, out of frequency range from the monitor. If I start Anymod and then Wolfenstein 3D it runs.

Micky

Put disable_mode_changes in CMDLINE/TXT. See here for details.

Jon, if you’re reading, it would be nice if this info was also in the How to install and use ADFFS thread.

I never noticed it wasn’t in that guide myself, but it’s in the info for the release https://forums.jaspp.org.uk/forum/viewtopic.php?t=624

>Put disable_mode_changes in CMDLINE/TXT.<

Did not work. I use a Raspberry Pi 3b+ with HDMI. Lowest frequency range is 640 × 480.

With Anymod it works. Why, I dont know it.

Micky

Anymode causes the Pi to output at the monitors native resolution, and the GPU then scales up whatever mode RISC OS is using to fit.

That means HDMI is the reason for mismatch frequencies.

I use a HDMI to Scart converter, but no success too.

Micky

Something doesn’t sound right. If you are running ADFFS and have disable_mode_changes in cmdline.txt you don’t need to use Anymode.

To test it with ADFFS running. Click menu over the Display icon and type 13 into the mode field.Then click the display icon. It should show the resolution and colours.

For mode 13 should show 320×256 with 256 colours.

Without ADFFS or anymode running RISC OS will pick the closest it knows about depending on what EDID sees or the hardcoded MDF has available.
The whole time the monitor should stay at the same resolution it defaulted to at start up. e.g. 19210×1080 @60Hz.

I use a HDMI to Scart converter

This won’t pass correct EDID data from the monitor, but might pass something created in the adapter, so the rpi might do something random. I think disable_mode_changes is meant to stop this.

I test it without converter.

Start ADFFS.

After typing in 13 and click OK the monitor has no picture but it shows:

Frequency out of range:
16 KHz / 50 Hz
Please change the display mode to 1280 × 1024 with 60 Hz

Same with mode 49. Error message is then:

Frequency out of range:
21 KHz / 43 Hz
Please change the display mode to 1280 × 1024 with 60 Hz

I must reboot Riscos because I can’t stop the monitor message.

Starting Anymode and ADFFS mode 13 did not work but mode 49. I start Doom and a short time came the message from the monitor that it is out of range. But then Doom start with picture.

Micky

It was my mistake. In cmdline.txt I wrote:

disable_gamma
disable_mode_changes

But correct is in one line:

disable_gamma disable_mode_changes

Now it works.

Thanks for the help.

Micky