Beginners FAQ:Hardware Support (Rev #8)

Q: Which file systems does RISC OS support
A: RISC OS supports FAT16 and FAT32 as well as its own (FileCore) file system.

Q: How do I remove my thumb drive safely?
A: Click MENU (middle mouse button) on the drive icon and select ‘Dismount’. If the drive was FAT32 you will notice that its name changes from ‘FAT32_0’ to ‘:0’. Now it is safe to unplug it.

Q: How can I format my thumb drive, so that RISC OS is able to read it from within RISC OS?
A: RISC OS currently only formats drives with its own (FileCore) format. If you plan exchanging data you should go for FAT32 on Windows/Linux/MacOS. To use the RISC OS file system see: using HForm.

Q: I have a spare USB hard disk. How do I use this on the RISC OS box?
A: You an use it with FAT32 or the RISC OS native file system (FileCore). See using HForm.

Q: What are the size limitations of the FileCore format?
A: FileCore supports up to 2 ²⁹ sectors, a sector is commonly 512 bytes, giving 256GB as the upper limit. Note that the controller used on the Iyonix motherboard can only use fast UDMA access to the first 128GB of the drive, the upper 128GB will use slower PIO accesses.

FileCore 3.61 and later allow for the maximum size of any individual file to be 0xFFFFFFFF bytes (4GB minus 1), earlier versions were limited to 0×7FFFFFFF bytes (2GB minus 1).

Q: How can I enlarge the RISC OS Pi SD card image to use the full SD card?
A: SystemDisc is part of the DiscTools suite, and is a general-purpose tool for managing the system software on modern RISC OS systems. SystemDisc allows you, easily and quickly, to initialise new SD cards for booting your RISC OS system, entirely from within RISC OS. It creates a two-partition SD card which can use all of the available space on your SD card. See this forum thread for a solution that adds a third FAT32fs partition on the original 2G SD card image where there is still free space on the SD card.

Q: Can I have an icon on my iconbar for my Fat32 filesystem?
A: Use ‘AddTinyDir’ to add an icon to your iconbar. Something like this should do the trick:

fat32fs:mount -p2 :16 { > null: }
addtinydir Fat32fs::fat32_16.$

Assuming that your fat32fs module is loaded in predesk (which is the default place to put it) you can pop the above commands in an obey file and either run it manually, or add it to the boot sequence to add the folder to your iconbar.

Q: Can I cache filesystems in RAM?
A1: Yes. !Memphis is a RAM based file system that auto-sizes to provide a cache for commonly used files. An option is available to automatically cache the !Scrap directories, which can lead to an improvement in performance for applications like !NetSurf which make a lot of use of this area.
A2: RISC OS provides RAMFS, which can be controlled from the !Configure utility.

Q: The Risc PC has CMOS RAM and a real-time clock. These were interrogated when RISC OS first started to establish the boot filing system and drive number as well as the current time and date. How is this done on the new platforms?
A: When RISC OS first starts up then the USB system is fired up in a minimalist way so that the keyboard can be recognised. If the delete KEY is held down then the ‘factory default’ settings for the CMOS are established (these are stored separately within the ROM image). If not then the memory above the rom is examined to see if a properly checksum’d CMOS settings file has been loaded there. If so, then that is used. If not then a particular area of the rom is similarly examined and, again, if that is properly checksum’d that is used. If the module ‘SDCMOS’ is present, then a file ‘cmos’ is examined in the same place (the SD card) that the rom was loaded from and that is used. Finally the IIC bus is examined to see if there is a hardware cmos widget presentand, if so, that is used. All of the available methods were used to save changed settings. From June 2013 this approach was found to give performance issues and the SDCMOS module was silently omitted from OMAP ROM builds. Although the bug was fixed in July 2013 (making the SDCMOS module inactive where a hardware cmos widget was fitted), the SDCMOS module was not reinstated until April 2014.

The user can influence this bahaviour by unplugging the SDCMOS module, by adding a cmos widget (the recommended approach) or by adding a ‘fatload cmos’ command to the boot script.

Holding down SHIFT (if the boot option is set) will leave the computer in supervisor mode rather than the desktop. Otherwise the boot process will decide from the configuration settings in the boot filesystem how to set the time: from a hardware real time clock, from a network-connected time server or, failing those, from the stored time and date when the computer was last shutdown.

Overall this gives users with or without a cmos widget the ability to retain settings after shutdown. Except for those without a cmos widget between June 2013 and April 2014 rom builds that is.