In this article I'm going to explain how the Raspberry Pi can be made to run RISC OS. In a few months time it will be possible to buy an SD card with RISC OS already written on it. Once this is available, you'll be able to simply slot the SD card into the Pi, switch on, and the set up will boot into the RISC OS desktop. From there you can run software, or write your own. This article is about getting to that point under your own steam. As such it embraces the Raspberry Pi philosophy of not being afraid to get "hands-on" and being DIY minded.
Here is how to write RISC OS onto an SD card.
In addition to the Pi you will need;
• Micro USB Power Supply (DC 5 Volts, 1 Amp output)
• Class 4 SD card of 4 GB
• USB mouse & keyboard
• HDMI monitor & connecting cable
I bought the Maplin N19HX power supply for £14.99, and an (Intenso) SDHC memory card for £3.99. I already had suitable keyboard, mouse, and monitor with cable. Class 6 SD cards are suitable but problems have been reported with class 10. Power supplies rated less than 1 amp (1000 mA) are a source of problems.
I used an Apple laptop (a MacBook Pro) to write the SD card. I only used what comes with it, built in. The laptop does not have an SD card reader so I used an adaptor to allow me to connect the blank SD card up to a USB port. Ordinarily, I use this adaptor, shown in figure 1, to pull photographs off SD cards from digital cameras.
The SD card image of the current 'alpha' version of RISC OS for the Raspberry Pi is obtained by clicking on figure 2. Many thanks to Chris Hall for packaging RISC OS in this user friendly way.
Figure 3 shows the file being downloaded on the Apple laptop.
This is a zip file so it needs unzipping before we can write the resulting SD card image onto the blank SD card. Double click on the zip file in the Downloads window, which will cause the Archive Utility window to appear. Figure 4 shows this window and, within it, the file in the process of being unzipped.
As the file finished being unzipped, a finder window opened to helpfully show me where the unzipped file had been placed, the relevant part of this shown in figure 5.
The More info... button is useful in obtaining the filepath to where the SD Card image has been parked. This will be needed. Figure 6 shows that mine is in /Users/helenjones/Downloads.
We're now going to access the command line within the Mac using the 'Terminal' app. Figure 7 shows where this can be found using 'Finder'. It's within Utilities in the Applications folder.
Double click on the image of the monitor in the finder window to open the Terminal window shown in figure 8.
With the blank SD card NOT plugged in, type df -h into Terminal. You should get something like figure 9.
Plug in the blank SD card via the adaptor into a USB port. Into Terminal again type df -h and compare your output with what was obtained previously. Mine is shown in figure 10.
The crucial line is the one that runs;
/dev/disk1s1 3.7Gi 1.7Mi 3.7Gi 1% /Volumes/Untitled
which was not present before and so must be the blank 4 GB SD card. This is further confirmed by the fact it is Untitled. We want the device name, which in my case is /dev/disk1s1 but *BE CAREFUL* yours may be different. Now unmount with the command;
diskutil unmount /dev/disk1s1
as shown in figure 11.
The tricky line comes next in which you need to accurately specify the pathname of the input file and where the output file is to be placed. For me this is;
sudo dd if=/Users/helenjones/Downloads/RISCOS_Alpha_13Jul2012.img of=/dev/disk1
as shown in figure 12.
Finally, eject the SD card with;
diskutil eject /dev/disk1
as in figure 13.
The job is now done. Take the card out of the adaptor, insert it into the Raspberry Pi and power on. After a short delay you should get the RISC OS desktop on screen. RISC OS looks for a DCHP server as it boots up. If you've not networked your Pi yet, press <Escape> to skip that step.
Next time, we'll look at some fun things to do with RISC OS.
With thanks to Helen Jones for the use of her Apple Laptop
Comments by email are welcome.
Chris Hill writes:
While sitting waiting for RISC OS to write to my SD card, I realised it would be faster if I added the parameter bs=1M to the dd command. This is on Linux (Ubuntu) but I expect it would work on a Mac too.
Chris is @Chillly on Twitter.
Readers without an Apple Laptop can install RISC OS on the Raspberry Pi using only a Raspberry Pi !
Step 1 - Boot up the standard Debian Linux from the standard Raspberry Pi SDHC card.
Step 2 - Plug in a 4 Gig USB memory stick and mount it - standard Linux mount.
Step 3 - Download the Alpha Image to the empty space on the 4Gig memory stick.
Step 4 - Plug in a USB adapter with a second SDHC card plugged into that.
Step 5 - Copy the image to the second card - sudo dd if=RISCOS_Alpha_13Jul2012.img of=/dev/sdb
Step 6 - Shutdown Linux, Change SDHC cards and Power up.
For those without a network, the image could be preloaded onto the 4Gig memory stick using any Windows PC (and quite probably, an Apple)
John also posts on the Raspberry Pi forum for RISC OS.
Matt Kevan writes:
Thanks for your guide to installing RiscOS on the Raspberry Pi. I'm really excited about playing with RiscOS again, having not used it since my trusty A410 died about 10 years ago. Just one thing; I noticed for someone fairly n00bish like me it's not immediately obvious that you need to drop the 's1' bit from the device name when running the dd command. Now I know it's important I can see it isn't in your example command, but it took me a couple of false starts and a fair amount of googling before I found out why it wasn't working. Also I discovered that as dd doesn't give any visual feedback, you can press CTRL-T to get a progress report.
Many thanks and keep up the hard work.