Beginners FAQ:Hardware Support (changes)

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This page answers some hardware-related questions about RISC OS. Further information about running RISC OS on specific hardware platforms can be found in the “Target hardware documentation” section of the Library index page.

Keyboards

Q: I’m using a compact keyboard that doesn’t have a Break key. How can I issue Alt-Break and Ctrl-Break?
A1: Many keyboards have a PAUSE key that performs the same function as BREAK.
A2: If your keyboard has neither key, use see KeyMapper¹The Break key to for substitute a another possible key workaround. of your own choosing. For example, to use “PrtScr” in this fashion, you would load KeyMapper and issue the command:
*keymap 13 15
This would allow Ctrl-PrtScr to behave like Ctrl-Break and Alt-PrtScr to behave like Alt-Break.

Monitors

Q: I’m using a FullHD (or 4K) monitor but RISC OS always starts up in 640×480. Why does this happen?
A: Some monitors auto-sense the input to use (HDMI/VGA/DisplayPort etc.) which introduces a delay into the monitor start-up process. Also, some hardware platforms (e.g. older models of Raspberry Pi) cannot drive a 4K monitor at full resolution. In these cases RISC OS is prevented from using the native resolution of the monitor, so uses “640×480 pixels, 256 colours” as a startup resolution instead.

The fix is to go to Configuration > Screen and change the resolution from its default setting (“Native”) to a value more suitable for your monitor (e.g. 1920×1080 pixels, 16 million colours). The start-up screen will still be displayed at a low resolution, but the desktop will appear at the chosen resolution.

Discs and filing systems

Q: Which file systems does RISC OS support?
A: RISC OS supports its own FileCore file system, as well as some non-native formats such as FAT (FAT12 or FAT16 or FAT32).

Q: How do I remove my disc safely?
A: Click MENU (middle mouse button) on the drive icon and select ‘Dismount’. Wait an extra 10-15 seconds for all disc activity to cease: it is now safe to remove the disc.

If the drive was using the FAT32FS module you may notice that its name changes from ‘FAT32_0’ to ‘:0’ also.

Q: How can I format my disc so that RISC OS is able to read it?
A: RISC OS currently only formats drives with its own FileCore format using the HForm utility. If you plan on exchanging data with other systems you should go for FAT32 on Windows/Linux/MacOS.
When formatting a FAT32 drive on another system, choose Master Boot Record (MBR) partitioning. Do not use “GUID Partition Table” – RISC OS cannot read that format.

Q: I have a spare USB hard disc. How do I use this?
A: Plug the drive into a spare USB port, it will be handled by SCSIFS as a mass storage device.

Q: What are the size limitations of the FileCore format?
A: FileCore supports up to 2²⁹ sectors, a sector is most 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).

FileCore 3.63 and later support sector sizes of 2kB and 4kB within the same 2²⁹ sector limit as before. Therefore the maximum drive size it supports is 2TB, though this does require the underlying filing system to talk to 4kB supporting hardware.

Q: How can I enlarge the RISC OS Pi SD card image to use the full SD card?
A1: 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.
A2: See this forum thread for a solution that adds a third (FAT32) partition on the original 2G SD card image where there is still free space on the SD card.

Q: How do I access both partitions on a boot SD?
A: Assuming the card is plugged into a USB card reader:
To access the DOS partition, click Select (left mouse button) on the drive icon.
To access the Filecore partition, click Adjust (right mouse button) on the drive icon. If you’ve already accessed the DOS partition, choose “Dismount” from the icon bar menu before trying to access the Filecore partition.
If the card is plugged into the SD card slot, only the Filecore partition will be accessible from the drive icon. Double-click on “Loader” (inside !Boot) to access the DOS partition.

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 have a temporary RAM file system?
A: RISC OS provides RAMFS, which can be controlled from the “Tasks” window (look for the “RAM disc” entry in the System memory allocation section). Drag the bar – or click where the bar should be – to change the size of the RAM disc. To remove the RAM disc when it is no longer needed, either drag the bar all the way to the left, or choose “Quit” from the RAM icon bar menu.

Other hardware

Q: The Risc PC stores configuration settings in battery backed CMOS RAM much like a PC BIOS does, how is this done on the newer platforms?
A: When RISC OS first starts up the hardware abstraction layer (HAL) attempts to detect the presence of a hardware CMOS widget – this add-on fulfils the same function as the chip in a Risc PC, but doesn’t need a battery backup.

If the CMOS widget is not found then a region of memory above the ROM is examined to see if a properly checksum’d CMOS settings file has been loaded there by a command in the script run by the OS loader (this is the mechanism used by the Raspberry Pi).

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. If no key is pressed then the settings already loaded are used.

The rest of the ROM modules are then started, which on systems with SD card interfaces may include the module ‘SDCMOS’. This module emulates the CMOS memory by saving it to a file on the SD card, but as it is not loaded until after the rest of the system has started cannot be used for some of the more advanced uses (like unplugging modules that conflict).

Q: The Risc PC keeps time via a battery backed clock chip, how is this done on the newer platforms?
A: The Iyonix, BeagleBoard and Titanium include a clock chip too, though the BeagleBoard may require a battery fitting as the circuit board is usually sold without.

The PandaBoard and Raspberry Pi can optionally fit an RTC plugin module, purchased separately. These may require additional software to be usable under RISC OS.

On all platforms, the time can be manually adjusted using the ‘Time and date’ configuration plugin, or set to collect the time from a network time server. The network time server will be called during the boot sequence, so if no network connection is present the time will be wrong.

The Raspberry Pi will also use the timestamp of the CMOS file (updated each time the computer is successfully shut down) to try to restart a software clock² – though of course this will be appear to be ‘frozen’ when the power is removed.

² This is done so that applications won’t see the system clock “jump backwards” after a reboot.