How small could you make a working computer?

I originally wrote this as a reply to rimar2000 in another forum.  It seems sufficiently interesting to warrant a separate discussion thread.

How small could you make a fully-operational personal computer (say, something with the capability of a Netbook).  I think the technology already exists to make one the size of a deck of playing cards:
  • Hundreds of GB of storage in something the size of a little MP3 player
  • WiFi transceivers fit inside a standard USB "thumbdrive" casing
  • Projected keyboards could be integrated (not a separate box)
  • The same technology could make an RGB projected display
  • A small footprint CPU (maybe with "embedded Linux") ought to be practical
Without a big display, hard drive, etc., you don't need much power at 5V to drive everything.  A standard cellphone battery (say 3.7V, 1000 mAh) ought to be enough to run such a machine for a couple of days between charges.

I'm not competent enough as an electronics engineer to prototype something like this, but it seems like a really great challenge for the DIY experts out there.  How small could you make a working PC using existing current technology?

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CameronSS7 years ago
<a href="http://www.linuxfordevices.com/c/a/News/Linux-Space-Cube-ready-for-blastoff/">Pretty darned small.</a><br />
kelseymh (author)  CameronSS7 years ago
Thank you, Cameron! I was both rolling on the floor and rather uncomfortable with the quote from a review towards the end of the article,<blockquote><div><em><span class="txt">The review tested the system as drawing a low 5 Watts</span></em><span class="txt">[sic]</span><em><span class="txt"> of power, and reports that "for such a small and low-powered PC, the Space Cube is actually pretty nippy."<br /></span></em></div></blockquote>A bit anachronistic to be sure, but still, referring to a Japanese product as "nippy"?!? How did the copy editors let that one through?<br />
sorry this is off topic but does anyone know why i am seeing html code above instead of seeing what the html actually does?
kelseymh (author)  Tanners7 years ago
I got the Space Cube link via Hackaday, but I see <a href="http://www.linuxfordevices.com/c/a/News/Tiny-tactical-mission-computer-runs-Linux/">another computer in the links at the bottom</a> that appears to be much more of a functional computer, albeit somewhat larger (3"x4.3"x7" instead of 2"x2"x2.1"). While the Space Cube only has 64MB of RAM and a 200MHz-300MHz processor, the DuraCor has 1GB RAM and a 1.4MHz processor, which is better than most netbooks. It doesn't have a connection awesomely labeled "<a href="http://en.wikipedia.org/wiki/SpaceWire">SpaceWire</a>", but it all of its connections are MIL-spec screw-on connectors, which are also cool, and the thing could keep running after it got run over by a dump truck.<br /><br />I saw one of those handheld projectors at Office Depot today...it was a non-working display model, I was really hoping to see one in action.<br />
Were there any editors that looked at it? There's a lot fewer of them about these days...

PKM7 years ago
As many people have pointed out, the average smartphone has more processing power than my desktop from ten years ago, and I did publishing and spreadsheets and played 3D games on that.

If you are looking for a "proper" computer, I think your playing cards estimate is about right.

Computer: Gumstix
Tiny, 600MHz processor, integrated 802.11 WiFi, add-on boards to interface with peripherals and add network connections etc- everything you need for the core of the system.

Keyboard/mouse: Gumstix computers can use USB through a breakout board, or a microcontroller can be used to interface with a keyboard.

Display: this is where problems arise. Projected displays aren't quite mature enough to be a proper solution in this much space, but there are pico projectors emerging which could project the display onto a nearby wall.

Power supply: a couple of Li-Ion phone batteries could power the device for a few hours, or you could give up trying to make it entirely self-contained and plug it into a wall-wart, or use inductive charging (a bit of a cheat).

If you don't mind not having a keyboard, mouse or display, the Sheevaplug is a decent existing product, and I'm sure it wouldn't take too much to add a couple of USB sockets for mouse/keyboard and a video output for a monitor or pico projector to one of those.
kelseymh (author)  PKM7 years ago
Thanks, PKM!  I knew about smartphones when I posted this; that was kind of my point.  These devices have crappy keyboards and displays for anything like real work -- try doing a multipage accounting spreadsheet for a corporation, or a CAD design, on an iPhone.  You won't be doing it for very long.

If you have to plug an external mechanical keyboard into the device, then the size of that keyboard counts toward the total size of the system.  Same goes for external displays.

My point was, how much of all this separate modular tehnology (including pico projectors) could be stripped of their casings and independent power supplies and company logos, and all put into one single box?  And how big or small would that box be?

Tethering to a wall-wart isn't completely unreasonable if you're doing fixed-site work, but portability and chargeableness :-) are obvious consequences of making a fully-powerful "desktop" computer fit in your pocket.
PKM kelseymh7 years ago
In that case, I think about the size of a Psion is a sensible minimum.  It has space for the components mentioned above, a decent-sized battery (at a draw of several watts, a phone battery wouldn't last long) and a usable keyboard.  Those laser keyboards are cool but I refuse to believe using one with no touch feedback at all is going to be pleasant.

Here's an idea- my current computer keyboard has at least four iPhones-worth of spare space at the top taken up by 8 mostly-useless media keys.

Why not go the route of the BBC micro et al, and have a full-size keyboard with the computer built into it?  You could easily fit a pico projector, small laptop battery, Gumstix board and so on into a PC keyboard.  I realise that what I have just described is quite similar to a crazy device called a "laptop", but if you want a really usable keyboard you need a keyboard.

That would be quite a fun project- find a keyboard with enough spare space in it and build a computer entirely inside it. Maybe a job for Ben Heckendorm?
PKM PKM7 years ago
OK, last post.  What about the size of a tangerine?

That includes a CF card reader, sound output, wired ethernet and even a VGA monitor port.  That is exactly the hardware I'd want for my hypothetical keyboardputer.

The LinuxStamp and CherryPal linked from that article might also interest you.  Getting the display out seems to be the hardest part- the "silver bullet" for this application would be a chip that can take character or pixel blitting input and generate the monitor signal on the fly.
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