Yesterday somebody said something about a "raspberry pie". So when I got 
home, I looked it up. It turns out Raspberry Pi is a kind of cheap, 
minimal computer system. It's powered by a 700MHz ARM11, which 
apparently is comparable in computational power to a 300MHz Pentium-II. 
It also has some kind of GPU onboard, which HDMI output. It's powered by 
USB, and the entire thing costs $35.

Naturally, I immediately asked myself whether you could build a cheap 
render farm out of these things. Having uttered the words aloud, at 
least one website about this subject must now exist. A trivial Google 
query verified this fact; there are indeed *several* such pages. They 
conclude that 100 Raspberries have roughly the same compute power is a 


In summary, you *can* do this, but the price per FLOPS is very poor. Or, 
it is if you use the *CPU*. My next question is what the hell happens if 
you try to use the *GPU* instead. I haven't seen an answer to this yet. 
(I also haven't looked very hard.)

Obviously the next important question is "can it run Haskell?" And the 
answer is obviously "yes" - although it seems it's difficult to compile 
anything particularly large on the actual machine itself, due to it 
having "only" 512MB of RAM.

You know, when I first learned Haskell, 512MB of RAM constituted a 
*very* high-end system. What the heck has the world come to when you 
need more RAM than that just to compile some source code?

(Then again, I haven't tried it personally. Perhaps they mean it can't 
really *huge* stuff like the entire Haskell compiler or something. They 
don't really quantify what constitutes "big".)

The goal of this project appears to be to churn out cheap computers that 
kids can mess around with to learn about computers and programming and 
stuff, similar to the way I did with the C64 when I was a kid. Trouble 
is, no kid today would find something as primitive as a C64 interesting, 
with its piffling 16-colour graphics and monophonic sound.

And there's the rub. It's got to be modern and powerful for anyone to be 
interesting. But if it's modern and powerful, it's going to be far too 
complex to tinker with at the level you would with the C64. If you have 
a C64, it's *feasible* to write a short machine code routine which 
performs a key-scan and pokes the video hardware in response to 
different key presses. You could, given a month of Sundays, 
realistically build your own micro-OS.

*Nobody* is ever going to do that for a Raspberry Pi. It takes something 
as complex as Linux to power it. Recall that Linux is the result of 
decades of effort by thousands of expert coders across the entire world. 
(And no, I'm not just talking about the kernel. The kernel, by itself, 
doesn't give you a runnable OS.) Nobody has the time or resources to 
write an entire OS in their spare time.

Similarly, with the C64 you can write a few POKE commands and watch the 
screen turn green or hear a sound play or something. The GPU on the 
Raspberry Pi are closed-source; you need to sign an NDA just to see what 
registers it has! Nobody is going to be experimenting with that anytime 
soon.

So, yes, it's a small hand-held computer with Python on it. But it's 
basically a normal PC, but smaller and cheaper. The fact that it's a 
bare PCB doesn't make it any more inviting to tinkering or whatnot. I 
suspect most kids are being to be really disinterested in this thing.

Now, the big kids who should know better? They might find this 
interesting...

Post a reply to this message

>
> Now, the big kids who should know better? They might find this
> interesting...

I seem to remember someone (Clipka?) trying to get POV to run on one...

Also, aside from the propeller-head scene, sone of the obvious 
applications for it would be as "single-function terminals" such as cash 
registers, call-center agent sets, ticket booths (movie theatres, train 
stations, etc...)

-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

Post a reply to this message

does it have a GPU at all?  if it is there, it may be more underwhelming than
any in the cheapest smartphone out there.  after all, it's not meant to run
games or smooth user interfaces, but to be tinkered by cli geeks... :)

Post a reply to this message

On Wed, 20 Mar 2013 19:59:19 -0400, Francois Labreque wrote:

> Also, aside from the propeller-head scene, sone of the obvious
> applications for it would be as "single-function terminals" such as cash
> registers, call-center agent sets, ticket booths (movie theatres, train
> stations, etc...)

Media centers seems fairly popular as well.

Jim

Post a reply to this message

On 21/03/2013 01:51 AM, nemesis wrote:
> does it have a GPU at all?  if it is there, it may be more underwhelming than
> any in the cheapest smartphone out there.  after all, it's not meant to run
> games or smooth user interfaces, but to be tinkered by cli geeks... :)

Supposedly it's meant to have hardware-accelerated real-time MPEG and 
H.264 decoding. It has HDMI output, after all...

It runs OpenGL and OpenVG, but I have no idea what 3D performance would 
be like. Unimpressive, I would imagine. (Remember, they're trying to 
make this thing cheap.)

Post a reply to this message

>> Also, aside from the propeller-head scene, sone of the obvious
>> applications for it would be as "single-function terminals" such as cash
>> registers, call-center agent sets, ticket booths (movie theatres, train
>> stations, etc...)

Seems reasonable. I could use one as an SSH server, for example.

(For reasons unknown, a bazillion SSH *clients* for Windows exist, but 
not one single *server* that doesn't cost £££.)

> Media centers seems fairly popular as well.

I must admit, I have no idea what that actually means.

Post a reply to this message

> And there's the rub. It's got to be modern and powerful for anyone to be
> interesting. But if it's modern and powerful, it's going to be far too
> complex to tinker with at the level you would with the C64. If you have
> a C64, it's *feasible* to write a short machine code routine which
> performs a key-scan and pokes the video hardware in response to
> different key presses. You could, given a month of Sundays,
> realistically build your own micro-OS.
>
> *Nobody* is ever going to do that for a Raspberry Pi. It takes something
> as complex as Linux to power it.

Download RiscOS for it - far simpler than Linux (no protection or 
multi-user) and very simple to write assembler within the built-in BASIC 
interpreter. By default the stuff you write will run as a single-task 
you have complete control over the machine. Also the whole GUI is 
ridiculously fast and responsive as it was originally designed for ARM 
processors under 50 MHz (the web browser is way faster than whatever the 
one included in raspbian, although not as feature-rich).

> Similarly, with the C64 you can write a few POKE commands and watch the
> screen turn green or hear a sound play or something.

You can issue poke commands from BASIC directly in RiscOS - IIRC ?<addr> 
is a variable you can use to read or write a byte to that address, or 
!<addr> to read/write a 4-byte word in one go. RiscOS BASIC also allows 
you to drop into the assembler very simply and then obviously reading 
and writing to memory is easily possible. The assembly language is 
pretty easy to learn.

The version of RiscOS for the pi also contains new software interrupts 
(that are easily called from BASIC) to read and write to the GPIO pins 
on the PCB. The following program will output a square wave on one of 
the pins (apparently at about 300 kHz).

REPEAT
SYS "GPIO_WriteData" ,17,1
SYS "GPIO_WriteData" ,17,0
UNTIL FALSE

> The GPU on the
> Raspberry Pi are closed-source; you need to sign an NDA just to see what
> registers it has! Nobody is going to be experimenting with that anytime
> soon.

AFAIK they haven't managed to get GPU access in RiscOS yet. If you 
wanted to do GPU stuff then you'd be better off with Linux, for example 
I use mine mainly with xbmc as a media centre, plays 1080p videos fine 
from an external drive through HDMI to a TV, so the GPU must be involved 
somewhere.

Post a reply to this message

Orchid Win7 v1 <voi### [at] devnull> wrote:
[SNIP]
> *Nobody* is ever going to do that for a Raspberry Pi. It takes something
> as complex as Linux to power it.
Not true, have a look at
http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/os/
> Similarly, with the C64 you can write a few POKE commands and watch the
> screen turn green or hear a sound play or something.
> The GPU on the
> Raspberry Pi are closed-source; you need to sign an NDA just to see what
> registers it has! Nobody is going to be experimenting with that anytime
> soon.
The GPU itself is closed source just as the GPU in your PC is.
Well, the Linux API is open so you do have a way to poke it and also the
framebuffer is available for bare metal programmers, AKAIK.
> So, yes, it's a small hand-held computer with Python on it. But it's
> basically a normal PC, but smaller and cheaper. The fact that it's a
> bare PCB doesn't make it any more inviting to tinkering or whatnot.
Does your PC have GPIO pins that you can access by simply writing '1' or '0' to
a file? I thought not. The Pi is the cheapest and easiest way to do physical
computing.

> I suspect most kids are being to be really disinterested in this thing.
There's actually a lot of kids writing their own stuff either in scratch or in
python.
>
> Now, the big kids who should know better? They might find this
> interesting...

Regards
Aydan

Post a reply to this message

On Thu, 21 Mar 2013 07:45:43 +0000, Orchid Win7 v1 wrote:

>>> Also, aside from the propeller-head scene, sone of the obvious
>>> applications for it would be as "single-function terminals" such as
>>> cash registers, call-center agent sets, ticket booths (movie theatres,
>>> train stations, etc...)
> 
> Seems reasonable. I could use one as an SSH server, for example.
> 
> (For reasons unknown, a bazillion SSH *clients* for Windows exist, but
> not one single *server* that doesn't cost £££.)

Wrong.  Cygwin comes with sshd based on openssh, and it costs nothing.

>> Media centers seems fairly popular as well.
> 
> I must admit, I have no idea what that actually means.

A PC that's hooked up to a TV to play audio/video.

Jim

Post a reply to this message

>> (For reasons unknown, a bazillion SSH *clients* for Windows exist, but
>> not one single *server* that doesn't cost £££.)
>
> Wrong.  Cygwin comes with sshd based on openssh, and it costs nothing.

It seems rather silly to install an entire Unix emulator just to run one 
tiny application... but sure, I guess that works.

>>> Media centers seems fairly popular as well.
>>
>> I must admit, I have no idea what that actually means.
>
> A PC that's hooked up to a TV to play audio/video.

Perhaps the part I don't understand is "why would you ever want to do this?"

Then again, I also don't understand why anybody would ever buy "digital 
picture frames"...

Post a reply to this message