Raspberry Pi interview: Eben Upton reveals all (Linux User) [LWN.net]

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 17:49 UTC (Tue) by jzbiciak (guest, #5246)
In reply to: Raspberry Pi interview: Eben Upton reveals all (Linux User) by karim
Parent article: Raspberry Pi interview: Eben Upton reveals all (Linux User)

Add up the price of purchasing those pieces and/or assembling them to the RPi and the Bone suddenly won't seem too bad.

To me, the Raspberry Pi is almost like the ZX81 of our generation -- just enough parts in it to call it a computer, and nothing more. But, to do anything useful, you need to start expanding it. But, the base system is cheap, cheap, cheap! Am I far off in this assessment?

How much do the things cost that you'll be connecting to either system? Presumably, you're connecting some form of input and some form of display. What happens when you apply an Amdahl's Law type of focus to the price of a complete, usable system, even if you didn't expand it with serial ports, JTAG, etc. and just stuck to, say, a keyboard, monitor and an SD card?

IIRC, a ZX81 wasn't that much less expensive than, say, a Commodore VIC-20 once you considered the price of a cassette recorder and TV to go with it, but their base retail prices had a similar ratio...

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Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 18:49 UTC (Tue) by dlang (guest, #313) [Link] (3 responses)

input is any USB keyboard/mouse

display is any HDMI enabled TV

power is a microUSB wall-wart. I've seen these <$10, but I have a half dozen sitting around the house right now, so I wouldn't necessarily need to buy one (this is the same thing a kindle, and most new cell phones use)

storage is a SD card, these can be <$10

what else do you need for your 'complete, usable system'?

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 19:06 UTC (Tue) by jzbiciak (guest, #5246) [Link] (2 responses)

Well, if you leave the TV out, then that adds another 50% to the price, roughly, if you assume you can get the keyboard, mouse, microUSB charger and SD card for $15-$20. Not too bad, I suppose.

A BeagleBone goes for $90. So, looking system to system, it's just over a 2:1 ratio: $110 vs. $50.

For many engineering geeks, I doubt the $60 differential is a huge deal breaker if you're only buying one. If you're on a much tighter budget, though, or buying many of these (either for many projects, or, say, outfitting for a lab full of students), I can definitely see the lower price being very attractive.

And to point out the obvious, I include the developing world under "much tighter budget." If the goal is to get computers into as many hands worldwide as possible, the BeagleBone is a much harder sell.

If you're just selling to tinkerers that have extra cash, it's hard to see how the Raspberry Pi is dramatically more compelling than the BeagleBone unless your project requires a many boards. I think distinguishing between different goals and scenarios might be helpful for evaluating their relative strengths.

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 19:49 UTC (Tue) by dlang (guest, #313) [Link] (1 responses)

well, does the beaglebone include the keyboard, mouse, charger, and an extra SD card? or would you have to get those for it as well?

Also, many people will have stray keyboards and mice around.

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 20:33 UTC (Tue) by jzbiciak (guest, #5246) [Link]

In the system to system price, I included the same $15 - $20 adder. Actually, I computed a $20 adder for the BB system vs. $15 for the RPi. If I correct the math, it's pretty much exactly 2 to 1: $90 => $110 vs. $35 => $55.

And sure, you may have a spare keyboard or USB power adaptor around (many tinkerers will), and that makes a difference when you're buying one or two to tinker with. My point is that you can't really count on that if you're, say, outfitting a classroom or doing some other mass deployment.

That brings me back to the final point I was trying to make: Tease apart the different scenarios where you might be choosing between these, and see how the strengths and weaknesses of each play into those scenarios. Reading through these threads, I see a bunch of goalpost shifting, because different commentators are assuming different use scenarios.

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 6, 2012 19:25 UTC (Tue) by gmaxwell (guest, #30048) [Link] (1 responses)

"is almost like the ZX81 of our generation"

Except for the fact that that most of the transistors in the main chip are locked up in a completely proprietary DSP which is why the devices needs an 18MByte binary blob to even boot.

...and the ARM CPU (really a coprocessor) is anemic enough that without this DSP there is basically no hope of reasonable video decoding on this platform.

Pretty lame from the perspective of an expirementer's platform, really.

Raspberry Pi interview: Eben Upton reveals all (Linux User)

Posted Mar 9, 2012 22:16 UTC (Fri) by WolfWings (subscriber, #56790) [Link]

The same description can be given to many thousand-dollar laptops I know regarding the CPU: Video decoding is wildly inefficient on the CPU versus the GPU/DSP, that's the nature of the beast. And, in fact, what GPUs/DSPs are created to assist with anyways. I've played 1080p video on my laptop with the CPU sitting at 800Mhz and all but one core switched off specifically because the GPU did it, if I used a software-decoder the system barely survives at 2*2.0Ghz chugging away.

CPUs are general purpose, but that doesn't mean they're maximally efficient for all workloads, especially insanely parallel ones like video decode/3D rendering.