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The instructions given below are suitable for models of Raspberry Pi up to and including the Pi 4B and Pi 400.
The Raspberry Pi 5 is not supported.
The Raspberry Pi bootloader files live in the DOS partition of the boot SD. On a standard RISC OS build using a Dual-format SD card, this can be reached by double-clicking on !Boot.Loader (i.e. shift-doubleclick on !Boot and then double-click on the file called “Loader”).
The Pi Zero, Pi 1, Pi 2 and Pi 3 use the following files:
bootcode.bin
– The boot loader for the CPU.start.elf
– The GPU firmware. Forms a matched pair with fixup.datfixup.dat
– Additional code for the GPU. Forms a matched pair with start.elfriscos.img
– The RISC OS ROMconfig.txt
– Configuration parameters for the boot loader. See below for suggested contents.cmdline.txt
– (Optional) Additional parameters to be passed to the kernel (i.e. RISC OS). See below for possible contents.On the Pi 4 (and Pi 400) the following two files take the place of bootcode.bin
, start.elf
and fixup.dat
:
start4.elf
– The Pi 4 GPU firmware. Forms a matched pair with fixup4.datfixup4.dat
– Additional code for the Pi 4 GPU. Forms a matched pair with start4.elfNote that the Pi 4 has its boot code in the onboard EEPROM so it does not need bootcode.bin.
If you have the latest beta ROM, there is a good chance that the latest Raspberry Pi firmware will work. Visit the Raspberry Pi firmware download site on GitHub to download the latest versions of bootcode.bin, fixup.dat, fixup4.dat, start.elf and start4.elf.
If you experience problems with the latest firmware – or if your RISC OS ROM dates from 2022 or earlier – you should try an older firmware release:
For the Pi Zero, Pi 1, Pi 2 and Pi 3, the procedure to follow is:
For the Pi 4B and Pi 400, the procedure to follow is:
From RISC OS:
From Windows/macOS/Linux:
This is a plain text file. The following example should be suitable for all models of Raspberry Pi, including the Pi 4B and Pi 400:
[pi4]
enable_gic=1
[all]
arm_64bit=0
fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
init_emmc_clock=100000000
kernel=RISCOS.IMG
ramfsfile=CMOS
ramfsaddr=0x508000
If you have a Pi 4B or Pi 400, config.txt must have a [pi4]
section containing the line
enable_gic=1
Parameters applicable to all models of Raspberry Pi appear in the [all]
section.
These parameters – and several others that may be of interest to RISC OS users – are discussed in more detail at config.txt (Raspberry Pi).
This file is optional: RISC OS will still boot if it is not present.
If you are running a development version of RISC OS (5.27, 5.29 or 5.31) you may need to specify the following parameter to avoid a blank screen issue.
disable_gamma
Parameters must be space separated on the first line of the file, so if you wanted to specify two parameters parameters, you would do it like this:
disable_mode_changes disable_gamma
For details of the parameters available, see cmdline.txt (Raspberry Pi).