News Samsung launches 8Gb GDDR5 chips, hints at PS4 redesign

Could a PS4 Slim be on the horizon?
http://www.bit-tech.net/news/hardware/2015/01/15/samsung-gddr5-ps4/1

 

Yes. Yes, I did. Fixed, ta!

 

My version is correct. A shock, I know. Note the capitalisation of the B: a lower-case b indicates bits; an upper-case B indicates bytes. There are eight bits in a byte¹, so one gigabyte equals eight gigabits. Eight 1Gb (one gigabit) memory chips connected together on a DIMM would give 1GB (one gigabyte) of storage capacity.

Eight 512MB (five hundred and twelve megabyte, or half-gigabyte) DRAM chips, by contrast, would give 4GB (four gigabyte) of storage capacity.

¹ For the purposes of our discussion there are, anyway. Yes, some systems have used oddly-sized bytes, but PC DRAM doesn't so I'm choosing to ignore that little fact.

 

Quite a lot, actually - at least, when you include supporting power circuitry and board traces.

 

Now read my *entire* sentence. Chip footprint is not the biggest cost, here. (Also, count the chips: you're missing half of 'em in that picture.)

 

(Apologies for aggressive snipping, here, as I'm on my phone.)

If I were redesigning the PCB, I'd leave the top chips alone and move some other components to where the bottom chips used to be to save maximum space.

Also, you're thinking two-dimensionally. Look up a picture of a BGA-packaged GDDR5 chip and count the number of solder balls on the underside. Every single one of those needs a PCB trace. The ones you see on the top of the board are part of the story: there are twenty-some layers to that PCB, and traces in all of them. Traces can't cross over each other on the same layer: the more traces you have, the more layers you need and the more complex the PCB. After a while, you hit an upper limit of layers and you need to start tracing circuitous routes to avoid existing traces, often jumping between layers using vias. What you see as empty areas of PCB are likely *filled* with traces you can't see - otherwise their be wasted space, and nobody likes wasted space - least of all the bean-counters.

Am I suggesting that simply halving the RAM chips will let Sony build a pocket-sized PS4? No. Am I suggesting that it could be combined with other advances made in the last two years (a more efficient PSU, perhaps, or new stepping of APU which draws less power) to build a PS4 smaller than the existing model? Yes
They've done exactly that in previous generations, so why are you suggesting it's impossible now? What makes the PS4 so different to the PS3, or PS2, or PS - all of which got slim variants, despite the original designs being exactly as jam-packed and optimal as e PS4?

 

Ah, but that part of the post wasn't present when I started composing my reply - sneaky! (As an aside: blimey, it's good to be back on the desktop. Editing replies on the phone is horrid.)

Well, no: as the article says, all Samsung is saying is that its new RAM could reduce the number of chips used in the PS4 (well, the games console that uses GDDR5 - which is the PS4) if used as a replacement for the (Samsung, incidentally) 512Mb chips currently in use with no cost to performance (to address the "but parallelism" complaint from above that I missed originally: given Intel's flagship Haswell-E processors' memory controller is quad-channel, what do you think the chances are that AMD's poor ickle Jaguar-based APU has a sixteen-channel memory controller on board to address all 16 512Mb chips at once? Choose from: no chance, zero chance, or not a chance in heck.) All Samsung cares about is a redesign of the PCB to accommodate its new chips; it couldn't give two hoots if the revised PS4 that results is smaller, the same size, or even bigger.

EDIT:
Almost completely off topic, but related to memory density and PCB design: the PCB for Uncle Clive's classic ZX81 microcomputer had room for two different density memory chips. Depending on what was available on the market at the time, it would arrive fitted with two 4Kb (512B) or one 8Kb (1KB) DRAM chips. You can see it on this picture of mine: my kit came with two 4Kb chips, but you can see a larger silk-screen (and the matching holes) for a bigger component marked IC4. That would have been the 8Kb chip, if it had been used. This way, Uncle Clive could use whatever RAM was cheapest on the market at the time without having to redesign the PCB. Externally, of course, the ZX81 would look identical - you'd never know whether it had one or two RAM chips inside, apart from perhaps measuring the slightly lower power draw of the one-chip variant.