Raspberry Pi is a series of credit card-sized single-board computers developed in the UK by Raspberry Pi Foundation with the intention of the teaching of basic computer science in schools. It was released in February 2012.
The original Raspberry Pi was based on the Broadcom BCM2835 system-on-a-chip(SoC). This SoC had ARM1176 processor which was ARMv6 architecture, along with Broadcom VideoCore IV GPU and 256 MB of SDRAM. And there was SDHC slot (for SD card) to be used for boot media and persistent memory (i.e., secondary storage like hard disk).
The original Raspi came in 4 models, namely A, A+, B, and B+. The SoC was same across all the models, but the RAM was increased from 256 MB to 512 MB in model B and B+. While A & B models had SDHC slot, A+ & B+ replaced it with Micro SDHC slot. The A & A+ models consume 1.5 & 1 Watt of power. The B & B+ models took 3.5 & 3 Watts of power respectively.
The Raspberry 2 released in February 2015, as of now comes in only one model, model B. The SoC is upgraded to BCM2836, which has an all new ARMv7 architecture processor Cortex-7 and is quad-core operating at 1 GHz. The RAM muscled up to 1 GB and VideoCore IV GPU is now dual-core . Rest of the system is identical to that of model B+ with 16KB of L1 cache and 128 KB of L2 cache, 40 pin GPIO header, CSI camera interface, four USB 2.0 ports and a 10/100 Ethernet port. Expecting Gigabit Ethernet though!
There’s a significant architectural change in RPi 2. The CPU & RAM are not on the same chipset any more. The RAM chip is Elpida EDB8132B4PB-8D-F and is moved to back of the board, which I think is to upgrade the RAM independently of SoC in future releases. You may think that the RPi 2 is just the upgrade of CPU and memory of previous B+ board. Which is true, however, RPi 2 has opened the doorway to realize CPU intensive applications and demanding I/O needs. And we’re going to see some amazing projects from this day on.
The primary goal is affordability.
- Raspi model A+ ==> US$20
- Model A & B+ ==> US$25
- Model B & Raspi 2 ==> US$35
- CM ==> US$30
There are Raspi ‘clone’ boards like Banana Pi, Orange Pi, Odroid, and Cubieboard which rub the shoulders with Raspberry Pi. But there are larger, more expensive and certainly more capable boards like HummingBoard and BeagleBone Black. Comparing them with Raspi should consider the price point. Truly that’s quite an achievement of RPi.