As to Qs for Pete Lomas

A couple of weeks ago, I had dinner with Pete Lomas, the Raspberry Pi Foundation trustee and all round good bloke who did the hardware design for the Raspberry Pi. It was a good opportunity to put some of the questions our Twitter followers had sent to him. (You may have seen Pete in some of our videos – he’s the fella in the lab coat and tartan trousers with the soldering iron and a fistful of capacitors.) At some point the names of those asking the questions went adrift from the questions themselves (entirely my fault) – if you asked one of these and would like to be acknowledged, please leave a comment below!

Pete’s answering questions here rather than on Twitter because he is constitutionally incapable of expressing himself in fewer than 140 characters. Over to Pete:

Why do birds suddenly appear every time you are near?

Cos I have bird seed in my pocket – why else?

Will RAM upgrades be available soon? And do you think you will move towards the multi processor boards?

We are looking at the possibility of a Model B+ with additional RAM, but the costs do not look promising and unless we really run out of space for the cool stuff people want to do then it will be a while

Why is the Pi selective about SD cards it will work with, surely the SD SDHC is a standard? [[Liz: This is about the problems we’ve had with Class 10 cards.]]

It looks like the jump to smaller die and process has created some anomalies that for some reason the BCM2835 cannot handle, this is also reflected in issues with Class 10. We will publish a tested list but we have already found that the same Card manufactured in different years – have different die, the early one is OK and the later one not. This is an issue and a real pain but we are looking at it.  It also affects microSD cards for identical reasons.

What beer do you like?

Peroni & Guinness – how end of the spectrum can you get. [[Liz: I will point out here that while Pete is trying to present himself as the Common Man in his beverage choices, we *did* spot a bottle of Cristal on his desk just before Christmas.]]

Are you surprised by the demand, or just feeling quietly justified that you’ve made something really cool that everyone wants?

Overwhelmed – never justified – we have a target to get these in schools and filling that gap – that’s my focus. However my 9 yr old son tells me its cool!

How to be so awesome?

(Do I even understand the question) I’d say do your best – s**t happens – but keep focused and you’ll get there…eventually.  That’s what I kept telling myself trying to route out the BGA…

Why alre the USB ports so misaligned with the ethernet one?! Ok, I know the answer, but tell him – crying – all the same!

When I saw the prototype I realised I’d messed this one up – my PCB symbol’s outline was just plain wrong – makes cases kind of interesting.  Eben is threatening to buy me beer until I agree to fix it – I think we will as soon as we spin.

Why no sound input on RPi ? (could have used the same audio jack but with 4 contacts – like on a mobile phone)

There are no inbuilt Audio ADC’s so there would be a cost adder – everyone was sat on my head to get costs down. They can be easily added via the GPIO.

Was there ever consideration to put Bluetooth on the Pi?

Would have been really cool but the budget would be blown – Bluetooth to USB is the way to go.

No holes, difficult casing :( Why not microSD and combined composite video + stereo jack to free some board space?

OK but mounting holes cost 7-8mm diameter where no tracks can go – could not see any sensible locations without compromising I/O.  In plastic it is quite easy to mould catches – there is something on the way…

Ask him if there is anything he would have done differently, knowing what he knows now? Also – What was the biggest sacrifice?

There are a few niggles with the design, mounting holes, connector alignment but in the basic design, but no, it does the job. The biggest sacrifice….hmmm staying sober to do the layout :-)…..seriously if it achieves the goal we have set – its awesomely worth it . Thanks for your support.

Can the fuses at USB be safely removed to provide >140 mA to USB or is there power concern that requires the limitation? [[Liz: I believe this is a question of interest to almost nobody but Abishur, but asked Pete to answer it because Abishur is a very helpful fellow around these parts!]]

The fuses kick in hard around 280mA and fold back and limit to 140mA. If you remove them then all you have for protection is the 700mA inbound fuse. The tracking on the board is good for 500mA+ so you could if you really wanted too. What about a powered hub – to power the Pi and bigger USB devices.

No questions, but please say THANK YOU PETE!

Thanks for you support – enjoy.

62 comments

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Hi Liz,

Great info there, just wondered if there will be an update on when the reworked first 10k Pi’s will arrive back in Blighty?

Cheers

Mike

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You’ll know as soon as we do.

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Just got notification from Newark/Farnell/Element 14 that my R-Pi is shipping on March 30th – next Friday! Happy Birthday, indeed, and thanks to you, Eben, and the rest of the team for this sweet little chocolate Easter Egg with a Raspberry nougat “centre”!

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Farnell (in their last missive) seemed confident that (what is now) 2-7 days would see them putting stamps on boxes.

No idea how much robbing off is involved in such an email though.

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“I seek not to know all the answers, but to understand the questions…”

Nonetheless, I very much appreciate you both taking the time to reveal this hidden wisdom. Many congratulations on all your hard work so far!

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Tks Pete :D!

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I was reading through it and went “ah! that’s me!” Thanks Liz!

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THANK YOU PETE

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Happy belated birthday to Liz. I am told the Rpi board is excellent. Like many still awaiting their delivery. Meanwhile created a co-blog with fellow raspberrians getting ready to program their slice . . .
http://raspberrypy.tumblr.com/
What languages do Pete and others at Pi HQ use? Liz do you know Python?

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Are you not worried about the Osborne effect, talking about the next model before your existing one has got off the ground?

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Well, given that, as Pete says here, we don’t even have plans to start working on one because the pricing doesn’t work out at all yet…no!

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Well. You can say that the Pi won’t run Windows until you are blue in the face, but will they listen to you?

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but surely, Windows 8 will run on ARM?

….sorry, I’m just leaving now… ;(

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As far as I can see all Pete is talking about is making the PCB slightly different. Which will effect only those who are working on cases. There will be nothing which makes the current ones obsolete,

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THANK YOU PETE!

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THANKS PETE! :)

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Peroni?! c’mon, you can’t be serious!

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A San Miguel Beer for you, Pete!

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“There are no inbuilt Audio ADC’s so there would be a cost adder – everyone was sat on my head to get costs down. They can be easily added via the GPIO.”

Can any provide a high level overview of what this would entain? Some form of daughter board? Can this be ‘easily’ done by someone with lots of linux skills but very little hardware skills (basic arudiono level).

Another question is any word on the Gertboard?

Thank you!

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Big thanks to Pete for all his work!

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Thanks for the As Pete, and to Liz for passing them on with the Qs!

One goof on the beta board traces while DUI (Digitizing Under the Influence :) ).

The misalignment of the connectors with the case faces deserves thirty lashes with a wet noodle … gives a whole new meaning to SMOP (a Small Matter Of Plastic ;) ).

Still can’t wait to receive my R-Pi!

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Liz, please check you email box, I wrote you some days ago but still not answer from you (only now I saw about you knee incedent on mountain.)

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Liz gets a lot of email – please be patient.

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As for sound input – USB microphones are pretty common these days, I assume that would work since the ADC is in the microphone?

I noticed that the logo now has a TM, although normally it’s not in a circle like (R).

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Just another thing to add… has there been a slight colour change in the logo? I’m sure it was more… purpley before.

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I thought so too, but it turns out that all that happened was the logo was made a little brighter (same colors less dark). I believe this was done by the designer of the logo? I forget, it’s not really important I guess, but the point is he thought the colors were too dark, but now they’re too bright :-P He’s working on getting it balanced out correctly to more correctly match that raspbery red color.

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I couldn’t resist drawing my own raspberry:

http://blog.chown.org.uk/2012/03/03/making-pies/

(This isn’t a criticism of the official logo. I just thought a 3D raspberry was an interesting thing to draw!)

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I will have to check whether actual raspberries are icosahedral, because if they are that is awesome.

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On other Linux systems, I’ve used the $1.29 USB audio interfaces often seen on ebay.

I was playing with using a stepper motor as a rotary encoder. If you turn the shaft on a motor, it acts as a generator. The interface I got only had a single channel input, so it would have taken two, to get quadrature input. Kind of a cabling mess for what amounts to a silly science demo.

[Kids, you can try this at home, if you have a disposable audio input. Don’t use the built in audio on your laptop, that is too expensive to replace. Engineering challenge: design a resistor network to limit the current, and put in some diodes to limit the input voltage. See if you can make it so it works at high speed, without destroying the audio inputs. In my experience, kids pay more attention to technology lessons, if there is a reasonable chance that something will blow up. $1.29 USB adapters make it affordable to blow things up.]

This is the companion silly science demo, to driving a servo motor from an audio output. Since you can generate precise sine waves in software, you get perfect control, down to the minimum frequency in your audio system. (Not good for holding position. Also, way less efficient than a real stepper driver.) [Kids! Back EMF can kill your audio amplifier. Don’t use anything you would get in trouble for destroying!]

Anyone know of any ultracheap USB interfaces that have stereo inputs?

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You can get external USB sound cards for about £10 that support 5.1 surround sound and 2x stereo inputs. I’ve got this one and it works pretty well:

http://www.ebuyer.com/106540-xenta-external-usb2-0-8-channel-sound-card-a-cm106

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Thanks. Google tells me, that that model is based on the cm106 chip and Linux supports it. Here are instructions for using to to drive a laser light show: http://laserpointerforums.com/f47/sound-card-dac-tutorial-40569.html

That exact model doesn’t look easy to get on this side of the pond, but there are some like it on eBay for just under $20(USD) including shipping to the US.

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Hey Liz, I am so so sorry, but there is a typo:

“Why alre the USB ports so misaligned with the ethernet one?!”

We will assume this was done on purpose.

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I just copied ’em verbatim. Spelling is not Twitter’s strongest point.

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So after so much hype the Raspberry Pi, which we still can’t have, looks more becoming a Raspberry Poo, after six years working on it, how come you screwed up using a wrong symbol outline ?, also issues with SD cards ? what other surprises we’ll find when (if we ever get them) the boards are finally shipped ?
Also using a CPU that is partially documented, well, that really sucks …

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And you stopped by and said that for your first post? Thanks! Well, I think you are a load of poo too. Do you spend a lot of time wandering round the internet insulting peoples hard work?
Oh, and please, try and learn some facts before commenting.

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troll, troll, troll your comments
all across the net
merrily, merrily, merrily, merrily
ignoring all the facts!

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thumbs up to Abishur

thumbs down to Jorge .. why not go away, create your own micro arm pc and undercut the price of the RasPi?

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First of all I don’t intend to insult anybody, it is not something personal.

Second I’m just expressing my opinion, I respect yours, you may not like or agree with mine and that is fine.

I’m not ignoring any facts and have been following the Rpi development for quite a while, to be frank I confess that personally it feels disappointing, but these are my feelings and I don’t expect you to feel the same way.

Third, I’m not going away and it is not in my plans to develop an ARM based PC, there are other ARM based boards out there that you can order, get shipped and work, obviously not at the same price but with more features, and calling the Rpi a “PC” is far stretched IMHO.

For those offended or hurt by my comments, my sincere apologies.

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If you’re truly being sincere then I’d come to the forums to discuss this, but fail to see how a device that uses a full fledged OS can be anything but a PC. I mean no one would deny the myriad of tablets and netbooks as being a PC. The pi uses a “CPU” from the the same family only at a lower clock speed. The lower speed hardly causes it to cease to be a PC. A mistake on the schematic that causes the USB to stick out is an inconvenience but hardly as big as you came across. It might also help to realize that they haven’t been working on this schematic for 6 years, they’ve been working on the concept for 6 years. It was the size of a usb stick at one point, this is just the most recent iteration so yeah there were going to be some “oops” moments. The SD card issue is one I’ve seen in Linux in general and not just limited to the R-pi, everyone has had to work to get it to work, it’s just that there are a lot more developers working with AMD and Intel so they already got the issue fixed. The “cpu” is only partially documented for non-business partners of broadcom, the reason why they chose this chip has been well documented, but the fact that they got *any* information released for it from Broadcom is nothing short of astounding! Finally, there shouldn’t be anything hardware wise left to discover, that’s why they haven’t released it. They took the time to properly test this rather than being like Apple (you’re holding the phone wrong!) Microsoft (Windows Vista) or Sony (Oops, Blu-ray 2.0 is nonbackwards compatible with 1.0, you’ll just have to buy all your movies over again)

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If you want to talk about facts, the BCM2835 is not comparable as a “CPU” to a SoC or Single/Multi Core Microprocessor as found on PCs and other devices as you mentioned. SC card issues and limitations are well known and many of them well documented and resolved. Comparing Microsoft, Apple or Sony with the R-pi foundation does not provide any solid argument.
I guess “the proof is in the pudding”, when we get it.
Do you have a R-pi already ?

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As I said, it is in the same family as tablets and netbooks with a lower clock speed, by definition that makes them non-comparable (which is to say non-equivalent) but that doesn’t change the fact that it is the same core technology. My comparison of Apple, Microsoft and Sony is to point out the flaws of not thoroughly testing your product before releasing it and meant only to be an illustration not an argument. These three companies pushed out a product when they knew they weren’t ready just to get the product out there. The RPF on the other hand has done diligent testing which is why they found each of these errors and gotten them fixed. No nasty hardware surprises there. No, I don’t have an R-pi, I’m not a developer.

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Dude, can you not appreciate the immense entrepreneurship? It is extremely rare to see new IT giant arising in the era we live in right now. It is because the technological hurdles to develop an entirely new platform are almost impossible to overcome. Are you genuinely saying all the achievements do not weigh up for a misaligned SD-card reader? That’s bullshit and you know it

You can call the raspberry pi whatever you like, though it’s a personal computer in much the same way the 8086 was used in PCs

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@reiuyi are you talking to me ?

Do you call RPF a new IT giant ? The Beagleboard, Beaglebone and many other boards are out there, you can buy them, get them and they work fairly good, and they are not pretending to create more buzz than Lady GaGa.

The Rpi still looks promising, still far away from a complete “PC” and the claimed $25. Will the RPF be able to deliver on their promise ?, really don’t know, so far the boards are not still out, there is no clear indication when they will be out, there is no word about what happened with the first 10K batch, we are learning about some hardware issues, the launch was IMHO a disaster and the distributors don’t seem to be doing such a great job.

For those that want to drop comparisons with Apple, they just sold 3 million iPads in 3 days, but the comparison doesn’t mean much.

Rpi == 8086 PC ? I think you can’t be serious, and if you want to talk about BS, you can point in other direction.

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And you completely ignore the facts I bring to the table. More and more you seem to be trolling :( It is by every definition a full fledged PC, it has always been a base price of $25, sorry you felt like that should include tax, vat, and postage, but it doesn’t work that way. I don’t know where you’re getting the idea that there’s no info on the 10K boards, look a few posts down on the home page.

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@jorge.
Yes, I have a Raspberry PI already. On it I run a full Debian linux with the LXDE desktop. It is, basically, a PC. It’s more powerful than the 8086 devices (in fact it performs at about the 300Mhz Pentium 2 level), and by every definition of the word, it is a PC. It also has much better video performance than many desktop PC of even more recent vintage. There is an intermittent SD card fault, that has been fixed on my build – this required some debugging by Broadcom (it was specific to the device), but is now done.
What was your question again?

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@JamesH
Are you saying the SD card issue mentioned by Pete Lomas in this post in no longer a issue?
(even for the coming first batch of Raspberry Pi’s)

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I’m not sure – I know there is a fix for a particular SD card problem, I just don’t know if its the one mentioned.

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My understanding is that the CPU is documented to about the same extent as the one in my desktop PC. There is a difference in that the Pi needs a microcode file to boot, whereas with a PC the microcode file is optional and just used so that your machine benefits from recent bug fixes. Both microcode files are closed source, though. Changing the Intel microcode would be quite interesting but it’s not obvious how you might go about it.

Similarly with the graphics support. Broadcom publish a closed source driver for the Pi, and nVidia publish a closed source driver for the PC. I know open source drivers would be nice to have, but at the moment graphics hardware vendors don’t want to give that much information away.

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I know it’s early, but in terms of “next gen” designs, has any thought gone into dealing with the problem that the BCM2835 has a v6 ARM, but many of the ARM supporting (desktop level) OSs are moving to supporting only v7 and later? I’d guess that the BCM28150/28155 are (way?) too expensive and beyond having more performance than probably needed (though dual cores would allow teaching uses to go into “true” parallel processing), they carry useless (for this application) baseband modems. AFAIK, (at least not under NDA) Broadcom hasn’t made any noise about a 2835 follow-on (i.e., low cost) with a v7 core.

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Way too early. There are only a couple of classes of problems that would warrant design changes in the near term. Highest priority would be if anything causes manufacturing issues. For example, if some connector isn’t available in sufficient quantity, it would make sense to change the board layout to support something that is available. If there aren’t any problems like that, then the next set of issues would be whatever causes severe problems for the target audience, which are the students.

If students aren’t bricking very many boards or blowing out an excessive number of GPIO lines, then you would want to give the community a few months to figure out how to use the current version. Then use that feedback for designing future versions.

People familiar with sourcing PoP memory chips will let us know when (if) the 512MB parts become affordable and available in quantity. No point in even asking the Foundation for a board with more RAM, while the prices are insanely high, or the distributors aren’t even stocking the parts.

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Late reply, but…

Not talking “near term”, just that I assume the RPF is in this for the long haul, and my experience in the industry is that by the time you ship a product, you are usually already fairly far down the path of designing (or at least architecting/spec’ing) the next one. These days you can’t really wait for the current product to be out in the field 6 months or a year before you _start_ thinking about a follow-on, or someone else will come along and replace you (and while the RPF says they don’t care who does this, I’d think they have too much time and effort invested to be that unconcerned about their own program’s long term).

Secondly, not talking about RAM. I date back to commercial real-time systems with 64KB of RAM, and have done very sophisticated datacomm systems in 1 or 2 MB. Unless you are tied to bloatware (which, admittedly, is becoming the case for some Linux distros), 256MB should be plenty for a long time, especially for an educational/real-time board. Further, as soon as parts are available inexpensively, a memory upgrade would be trivial.

No, I am talking about processor architecture, which has more significant impact. As I said, the problem is that the ARM core in the BCM2835 is a v6, and it appears that the mainline “desktop” OS releases (and in particular, the major Linux distros, like Ubuntu) may not provide support for v6 in the not too distant future (going for v7 or later only). This is not insurmountable – software for v6 can still be built – but it adds the requirement for a lot of time and resources that aren’t directly relevant to the RPF’s intended target, which is to provide a low-cost but fairly general purpose educational platform that _leverages existing infrastructure_ so they can concentrate on the educational bits.

They chose the BCM2835 because it was an existing, low-cost, highly integrated solution that did (most of) what they needed to meet that target. However, it isn’t ideal for their needs (not surprising – it wasn’t designed with their requirements in mind), and in particular, the ARM core it contains will, over time, become problematic (in fact, it already is, as they were originally intending Ubuntu to be their “preferred” standard distro, but it cannot be used for this specific reason). Therefore, it isn’t a ridiculous idea that they be giving this (and other practical limitations that exist in the Pi because of specific tradeoffs that exist in their design and the components they chose) some thought…

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Thanks, Pete! And thanks to everyone else who’s making a positive contribution.

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Thanks indeed Pete.

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Found one mistake, sorry. I believe the correct answer is:
“Why do birds suddenly appear every time you are near?”

Just like you, they long to be, close to me.
:)

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Can anybody explain in more detail what “Compliance testing” entails ? as mentioned in the last update from RS and how much longer it will represent to have the boards available ?

Is it “testing” or “certification” ?

Thanks in advance

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There’s a discussion about it in the forum (here’s a link) but Liz gave a very comprehensive answer in the comments of the Programming the Raspberry Pi webinar (here’s a direct link for you)

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Thanks, also read Eben’s post later today.

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You guys are doing an awesome job, and I hope to get my hands on one soon.

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http://www.bunniestudios.com/blog/?p=918

this blog post explains some SD card troubles that other people have had, may explain part of the pi problems with SD cards

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A fascinating read! I’m not sure if that’s what’s going on with the r-pi, but quite the fun read regardless!

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