Raspberry Pi questions and answers (Rev #1)

Introducton

This page contains a number of general issues that may crop up when running RISC OS on the Raspberry Pi, but they don’t each deserve a page to themselves.

Boot (and !Boot) issues

Can I boot the Pi from USB (without an SD card at all)?

You can do it on the Pi 3B+ and Pi 3A+, but it’s not recommended. The reason is that RISC OS expects the CMOS file to be on the SD card – see CMOS RAM on the Raspberry Pi – so if you boot from USB your configuration changes will not be saved properly.

You could get round the problem by manually issuing SaveCMOS every time you make a configuration change, but it’s not a pleasant solution, and you will at some point forget to do it.

Can I move !Boot to an external disc drive?

Why moving !Boot is a good idea

Having !Boot on the SD card means that the SD card will see lots of writes (thanks largely to the presence of !Scrap inside !Boot). While an SD card does provide a low-cost storage medium, it must be remembered it was designed for use by devices such as digital cameras which would be writing a series of (say) 2MB files rather than the 1kB used by Filecore: this can result in the SD card performing substantially more write operations than expected. Also, the SD card does not understand Filecore format so does not know when a file has been deleted: this means that the wear levelling algorithms will become progressively less efficient as the drive fills up, leading to a reduced operating life.

tl;dr – You can improve SD card longevity by moving !Boot somewhere else.

How to do it

1. Copy ¹ !Boot to the root directory of the chosen device, e.g. SCSIFS::4
2. Press F12 and issue the following two commands:
   *configure filesystem SCSI
*configure SCSIFSDrive 4
3. Reboot.

Remember that you must retain !Boot.Loader on SDFS::0, but you can get rid of everything else on the SD card once you are sure that the system is using !Boot on SCSIFS::4.

¹ You must use Copy, not Move. Apart from the !Boot.Loader issue, there is the small detail that RISC OS is at this point using !Boot on the SD card, and could get upset if some (or all) of it were to go missing mid-session.

System configuration

Why are my configuration changes lost when I shut down?

This indicates that either the “CMOS” file is missing from !Boot.Loader, or you have ended up with two “CMOS” files (one in the root directory of the SD, the other in !Boot.Loader). This is explained further in CMOS RAM on the Raspberry Pi.

The fix is to issue *SaveCMOS !Boot.Loader.CMOS and – if necessary – rename (or delete) any file named “CMOS” in the root directory.

Why is the system clock showing the wrong time?

The Pi does not have a real-time clock. Hence, when the Pi boots up, it will not be aware of the correct time.

The fix is to run an Ethernet cable from the Pi to your broadband router (or equivalent network port with access to the Internet). The Pi will then be able to update its clock from the network.

Note: Several “real-time clock” add-ons are available for the Raspberry Pi, but will require custom software to work with RISC OS.

Other

Why can’t I use the onboard WiFi chip?

RISC OS does not currently support WiFi on any platform. Adding WiFi support to RISC OS is a major undertaking, but it is on the roadmap so will (we hope) eventually appear.