Category Archives: Raspberry Pi

pi-topRO – the new RISC OS portable computer

It has been a long time coming but Fourth Dimension (4D) is now pleased to announce that we are able to supply the first RISC OS portable computer since Acorn’s A4 (launched in 1992).

Based on the ‘pi-top’ and incorporating the Raspberry Pi model B[1].
Extensive work has been undertaken to add full RISC OS support.

pi-topRO in Grey
pi-topRO in Grey

Screen: 13.6″ HD Screen 1366×768 (1360×768 on RISC OS)
Battery Life: 10+ hours
82 key keyboard
16GB microSD card with RISC OS 5
Power saving features!

RISC OS software included:
RISC OS 5 installed
!PowerOff – Turns power off at shutdown
!SpkrSetup – To enable the speaker
!BatteryMon – Reports battery usage including estimated time left
!Brightness – Controls screen brightness
Custom MDF
Screensaver – turns screen power off
!HID with custom setup file

Complete system with Raspberry Pi 2 or 3, software as above, speaker, RTC, and nano WiFi router £499 including UK delivery.

More details and purchasing information is available at

Available for immediate despatch.

The keyboard is 86% the size of a RiscPC keyboard. As with most portable/small keyboards some compromises have had to be made, the function keys are accessed using a ‘Fn’ modifier key. Break and most normal keys are available.

Update for pre announcement purchasers: The ‘Fn’ modifier key will work correctly if in !Configure you set ‘Num Lock’ OFF! NB. Not having to use the ‘pi-top’ modifier key also seems to significantly reduce spurious key entry and repeats. Thanks to Jon Abbott for spotting the cause.

The system is also available without a nano WiFi router and/or speaker. Software and hardware upgrades are available separately for users who have already purchased a pi-top.

Software and hardware upgrade kits for the pi-topCEED coming soon!

[1]Users can choose the latest model Raspberry Pi, the Pi 3, or go with the Pi 2 for currently greater software compatibility.

Measuring your Raspberry Pi’s low power!

We all know that the Raspberry Pi is low power, but just how low is the power consumption of your set up?
Measuring the voltage is easy with a digital meter but measuring current (to give you power) is awkward as you need to break into the power line and wire it through the meter whilst maintaining good contact at each join. Our USB Voltage & Current meter is plug and play and will tell you accurately just how much power you are using (Power in Watts = Volts x Amps) by giving you voltage as well as the current you can also detect under specced PSUs or dodgy cables.

Our neat little USB Voltage & Current meter has a USB A plug and socket and measures the power coming out of a USB socket so we include suitable adaptors/cables.

If powering your Model A, B or B+ Pi via its microUSB socket this will do the job:
Photo of DVM connected to a Pi B+
For specs and more details or to buy please see our Order Page

If you are reverse powering a Model A or B through a Pi’s USB A socket then a different cable & adaptor is required, as shown below:
Photo of Digital Meter measuring power going into a USB A Socket
For specs and more details or to buy please see our Order Page

n.b. We could have used a solid USB A plug to plug adaptor but that would result in a 10cm long solid block being plugged into the Pi’s USB socket which could mechanically strain the socket more than we think advisable. By using a good quality USB A- A cable no significant voltage loss is made.

Adding a meter, cable & adaptor will affect the power getting through, but we were very pleasantly surprised to see that measuring the voltage on the Pi TP1 to TP2 only dropped 0.06V when the meter with adaptor and cable was added.

When testing on a reverse power model B, a cheap 55cm USB A -A lead we tested had a 1V drop across it!

Add a power switch to your Raspberry Pi!

The Pi has no on board power switch, which can be a pain! Unplugging and re-plugging the power cable isn’t ideal.

However you power your Pi we probably have a power switching option for you, basically whatever cable carries the power we can provide a version with an in-line switch or an extension cable with one!


Only NINE options!

Powering a Pi via its microUSB socket is normally the best option as that leaves both USB ports free for data. The most common option is a dedicated PSU: PSU for Raspberry Pi UK (Mains plug to microUSB plug) 1200mA with in-line On/Off Switch


Standard 2.1mm DC socket to microUSB plug with in-line switch. Very useful if you want to power other items like small LCD monitors also at 5V as you can then use a DC splitter cable and run everything from one PSU! Also could be used with some Power over Ethernet (POE) units including ‘Spare Wires POE’


Standard 2.1mm DC plug to microUSB plug with in-line switch. A 2.1mm plug version of the above for use with equipment that can supply power from a 2.1mm socket like some POE adaptors e.g. TL-POE10R (POE10R + Switched cable)


If you power your Pi via its microUSB socket then this short lead can plug in-line with whatever your current power source is: microUSB extension cable with in-line switch (microUSB Female to microUSB Male 20cm approx.)


USB A Male to microUSB Male for Raspberry Pi with in-line Power Switch
For powering a Pi through its microUSB socket from a powered hub or other computer’s USB port or a PSU with USB A socket/s


USB A extension cable USB Power/Data cable USB A Female to USB A Male for Raspberry Pi with in-line Power Switch.
Short extension cable with ON/OFF switch suitable for powering your Revision 2 Pi via a USB A socket. One use would be for connecting to a powered hub with captive input cable


USB Power/Data cable USB A plug to USB B for Raspberry Pi including Power Switch
Power and data cable with ON/OFF switch for powering your Revision 2 Pi via its USB A socket from a powered HUB with a USB B socket.


Combined USB Power and Data cable for Atrix LapDock to Raspberry Pi including power switch
Provides a very neat solution for connecting an Atrix LapDock to your Pi.
Connects the microUSB on an Atrix LapDock to Raspberry Pi Rev.2 USB port, providing a USB connection and switched power. Upon the advent of the MK2 Pi we realised that a much neater solution than was previously used (modified splitter cables) was a microUSB Female to USB A Male but we couldn’t find such a cable, so set about making one. microUSB Male or Female cannot be hand assembled reliably but we could source factory made microUSB extension leads, so all we needed to do was solder on a standard USB A Plug, but even that we decided would be difficult to do to the quality needed for a commercial product. Then we had a minor Eureka moment and realised that if we put an in-line switch mid cable we could could use factory assembled leads for the two parts and make the in-line connections within the switch for a reliable professional looking cable. When used with our microHDMI Female to HDMI Male cable it makes a simple, neat LapDock Pi system.


iTX/ATX POWER Control Module & Real Time Clock module for the Raspberry Pi
I’m planning a more detailed blog about the iTX/ATX/? Power Control module later.


All of the above are normally available from stock!
We ship world wide and can offer quantity discounts on orders of five or more

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