When the Raspberry Pi was first released, its creators hoped to sell a thousand units. Instead, they created one of the most popular and enduring low-cost computers to ever come to market, with sales of 19 million units as of March 2018. Since the $35 computer debuted, it’s been offered in a variety of form factors and capabilities, but the current Model B+ has used the same ARM CPU (Cortex-A53) since it debuted in 2016. The Raspberry Pi Foundation has been fairly good about tweaking the design to improve performance while keeping the price the same, but what are the chances for a near-term improvement — or a Raspberry Pi 4?
Eben Upton, the creator of the Raspberry Pi, recently told Tom’s Hardware what to expect and when to expect it. The bad news? There’s no RBP4 coming to market just yet. The good news? When the diminutive machine does appear, it should pack some significant improvements.
One major change with the next generation is the move away from 40nm manufacturing. Upton expects the next-generation of Pi to move away from this venerable process node and to something more recent. 28nm seems to be the most likely target (7nm was definitely out). This makes sense. Price is central to the appeal of the Raspberry Pi, and 28nm is a well-established, low-cost node already, with substantial performance improvements over 40nm.
Like its predecessors, the Pi 4 will keep its $35 price tag, despite inflation making that a bit tougher to target than it was back in 2012. It won’t be larger than the Raspberry Pi 3B+ or smaller than the Pi Zero. “I think everyone’s wish list for the product looks the same: more processor, more RAM, faster network [and] faster non-multimedia I/O,” Upton told Tom’s Hardware.
Keeping the price tag at $35 limits just how powerful the RBP’s hardware can be, but there are a few obvious places where performance and features can be improved. ARM’s Cortex-A55 is a good place to start. It’s the improved version of the A53, with better branch prediction, an improved memory subsystem, better cache performance, independent load/store units, and support for ARM’s DynamIQ technology (though it’s not clear if this is relevant to the Pi’s use-case). As the graph above shows, the overall performance improvement relative to the Cortex-A53 should be significant.
This, to be clear, is total speculation on our part. But it would be logical for the Pi 4 to move to ARM’s modern low-power 64-bit processor when it makes the shift to 28nm or below. The Cortex-A55 on 28nm should be capable of using LPDDR3 and possibly LPDDR4. Either would provide a significant reduction in power consumption compared with LPDDR2, but I’m not sure why using a 40nm process limits the current RBP 3 to LPDDR2, so I don’t want to assume LPDDR4 is available to 28nm designs. Regardless, it seems likely that Pi enthusiasts can look forward to at least 2GB of RAM, possibly more, when the system finally ships.
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