Published on July 8th, 2012 | by Richard Cartwright0
A Slice of Raspberry Pi Hardware
Time for another slice of Raspberry Pi. I had hoped to be able to provide a hands on hardware review, but alas I am still on backorder. The Raspberry Pi Foundation’s offering to encourage both stodents and hobbyists to get hands on with coding and hardware come in two types, the Model A and the Model B. The Model A has 256 MB of onboard memory, aone USB port and that is it. The Model B adds an additional USB port for a total of two and an Ethernet port as well. Both devices come with an HDMI and a RCA video port, plus a standard audio jack. There is no VGA port because the designers believe that VGA is on the way out as a display standard and want to cater to re purposing old tube TVs or flat-screens as cheap display options. There is also a slot for an SD card that is envisioned to be the source for the operation system to boot. At present there is no case provided, but there are several on offer and in the spirit of re-purposing ,modders have used an old Super Nintendo set or a BBC Micro case design along with the LEGO creation form our last post.
As you can see from the schematic, things are compact. In fact the card weighs in at 45 grams and measures a trim 85.6mm by 53.9mm and 17mm high, although the connectors and slotted SD card will poke out a bit. The petite size is achieved because the Raspberry Pi is a system on a chip or SoC design powered by a Broadcom BCM2835, containing an ARM1176JZFS, with floating point, clocked at 700Mhz. The Videocore 4 GPU accesses 3D functions via Open VG and Open GL ES2.0 libraries. The graphics processor is able to delever 1Gpixel/s, 1.5Gtexel/s or 24 GFLOPs of general purpose processing power., plus Blu-Ray video output via H264 at 40MBits/s. The 256MB of RAM is part of the SoC and cannot be swapped or added to either.
For those of you who worship at the altar of overclocking, since the Raspberry Pi has no BIOS to speak of , overclocking is no easy task but according to the Foundation, the system could be nudged up to around 800Mhz. Speaking of clocks, there is no real time clock either, but one can be added using the GPIO pins. For those of you trying to puzzle out where the power switch is, look no more because there is not one. Plugging the supply in and removing the plug to power it down is as good as it gets. Further, as mentioned in the prior post, you have to purchase a power supply separately. The board is powered by a five volt micro-USB which will allow most any late model phone charger to do double duty provided that it can supply at least 700mA for the Model B. The Model A needs only about 300mA since there are no additional USB or networking ports to supply.
Benchmarks are not available as such, but the Foundation states that the graphics capabilities are “…roughly equivalent to Xbox 1 level of performance. Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics.” Users can hook up a mouse and keyboard using the USB port and a USB hub in tandem. Peripherals would be a function of the operating software, which we will be serving up next time.