Author Archives: Eben Upton

Learn to write games for the BBC Micro with Eben

via Raspberry Pi

Long-time fans of the Raspberry Pi will know that we were inspired to make a programmable computer for kids by our own experiences with a machine called the BBC Micro, which many of us learned with in the 1980s.

This post is the first of what’s going to be an irregular series where I’ll walk you through building the sort of game we used to play when we were kids. You’ll need a copy of BeebEm (scroll down for a Linux port if you’re using a Pi – but this tutorial can be carried out on a PC or Mac as well as on an original BBC Micro if you have access to one).

I’m going to be presenting the next game in this series, tentatively titled Eben Goes Skiing, at the Centre for Computing History in Cambridge at 2pm this afternoon – head on down if you’d like to learn how to make scrolling ascii moguls.

Helicopter tutorial

We’re going to build a simple helicopter game in BBC BASIC. This will demonstrate a number of neat features, including user-defined characters, non-blocking keyboard input using INKEY, and positioning text and graphics using PRINT TAB.

Let’s start with user-defined characters. These provide us with an easy way to create a monochrome 8×8-pixel image by typing in 8 small numbers. As an example, let’s look at our helicopter sprite:

Each column pixel position in a row is “worth” a different power of 2, from 1 for the rightmost pixel up to 128 for the leftmost. To generate our 8 numbers, we process one row at a time, adding up the value for each occupied pixel position. We can now create custom character number 226 using the VDU 23 command. To display the character, we change to a graphics mode using the MODE command and display it using the PRINT command.

Type the following:

10MODE 2

70VDU 23,226,0,248,32,116,126,116,112,0

RUN

PRINT CHR$(226)

You should see the little helicopter on the screen just above your prompt. Let’s define some more characters for our game, with character numbers 224 through 229. These represent leftward and rightward flying birds, a rightward flying helicopter, the surface of the sea, and a landing pad.

Type the following:

50VDU 23,224,0,14,12,104,16,28,8,0

60VDU 23,225,0,112,48,22,8,56,16,0

80VDU 23,227,0,31,4,46,126,46,14,0

90VDU 23,228,0,102,255,255,255,255,255,255

100VDU 23,229,255,255,0,0,0,0,0,0

Trying running your program and using print to view the new characters!

Now we’re ready to use our sea and platform characters to build the game world. Mode 2 on the BBC Micro has 20 character positions across, and 32 down. We’ll draw 20 copies of the sea character in row 30 (remember, rows and columns are numbered from zero) using a FOR loop and the PRINT TAB command, and pick a random position for the platform using the RND() function.

Type the following:

110FOR I%=0 TO 19

120PRINT TAB(I%,30) CHR$(228);

130NEXT

140P%=RND(20)-1

150PRINT TAB(P%,30) CHR$(229);

RUN

You should see something like this:

Don’t worry about that cursor and prompt: they won’t show up in the finished game.

It’s time to add the helicopter. We’ll create variables X% and Y% to hold the position of the helicopter, and Z% to tell us if it last moved left or right. We’ll initialise X% to a random position, Y% to the top of the screen, and Z% to zero, meaning “left”. We can use PRINT TAB again to draw the helicopter (either character 226 or 227 depending on Z%) at its current position. The whole thing is wrapped up in a REPEAT loop, which keeps executing until the helicopter reaches the ground (in row 29).

Type the following:

160X%=RND(20)-1:Y%=0:Z%=0

180REPEAT

260PRINT TAB(X%,Y%) CHR$(226+Z%);

290UNTIL Y%=29

RUN

You’ll see the helicopter sitting at the top of the screen.

We’re almost there: let’s give our helicopter the ability to move left, right and down. On each trip round the loop, we move down one row, and use the INKEY() function to read the Z and X keys on the keyboard. If Z is pressed, and we’re not already at the left of the
screen, we move one column left. If X is pressed, and we’re not already at the right of the screen, we move one column right.

Type the following:

210IF INKEY(-98) AND X%>0 THEN X%=X%-1:Z%=0

220IF INKEY(-67) AND X%<19 THEN X%=X%+1:Z%=1

230Y%=Y%+1

RUN

You should see something like this:

The game is much, much too fast to control, and the helicopter leaves trails: not surprising, as we didn’t do anything to erase the previous frame. Let’s use PRINT TAB to place a “space” character over the previous position of the helicopter, and add an empty FOR loop to slow things down a bit.

Type the following:

190PRINT TAB (%,Y%)"";

280FOR I%=1 TO 200:NEXT

RUN

Much better! This is starting to feel like a real game. Let’s finish it off by:

  • Adding a bird that flies back and forth
  • Detecting whether you hit the pad or not
  • Getting rid of the annoying cursor using a “magic” VDU 23 command
  • Putting an outer loop in to let you play again

Type the following:

20REPEAT

30CLS

40VDU 23,1,0;0;0;0;

170A%=RND(18):B%=10:C%=RND(2)-1

200PRINT TAB(A%,B%) "";

240A%=A%+2*C%-1

250IF A%=0 OR A%=19 THEN C%=1-C%

270PRINT TAB(A%,B%) CHR$(224+C%);

300IF X%=P% PRINT TAB(6,15) "YOU WIN" ELSE PRINT TAB(6,15) "YOU
LOSE"

310PRINT TAB(4,16) "PRESS SPACE"

320REPEAT UNTIL INKEY(-99)

330UNTIL FALSE

RUN

And here it is in all its glory.

You might want to try adding some features to the game: collision with the bird, things to collect, vertical scrolling. The sky’s the limit!

I created a full version of the game, using graphics from our very own Sam Alder, for the Hackaday 1K challenge; you can find it here.

Appendix

Here’s the full source for the game in one block. If you get errors when you run your code, type:

MODE 0
LIST

And compare the output very carefully with what you see here.

10MODE 2
20REPEAT
30CLS
40VDU 23,1,0;0;0;0;
50VDU 23,224,0,14,12,104,16,28,8,0   
60VDU 23,225,0,112,48,22,8,56,16,0
70VDU 23,226,0,248,32,116,126,116,112,0
80VDU 23,227,0,31,4,46,126,46,14,0
90VDU 23,228,0,102,255,255,255,255,255,255
100VDU 23,229,255,255,0,0,0,0,0,0
110FOR I%=0 TO 19
120PRINT TAB(I%,30) CHR$(228);
130NEXT
140P%=RND(20)-1
150PRINT TAB(P%,30) CHR$(229);
160X%=RND(20)-1:Y%=0:Z%=0
170A%=RND(18):B%=10:C%=RND(2)-1
180REPEAT
190PRINT TAB(X%,Y%) " ";
200PRINT TAB(A%,B%) " ";  
210IF INKEY(-98) AND X%>0 THEN X%=X%-1:Z%=0  
220IF INKEY(-67) AND X%<19 THEN X%=X%+1:Z%=1
230Y%=Y%+1
240A%=A%+2*C%-1
250IF A%=0 OR A%=19 THEN C%=1-C%
260PRINT TAB(X%,Y%) CHR$(226+Z%);
270PRINT TAB(A%,B%) CHR$(224+C%);
280FOR I%=1 TO 200:NEXT
290UNTIL Y%=29
300IF X%=P% PRINT TAB(6,15) "YOU WIN" ELSE PRINT TAB(6,15) "YOU LOSE"
310PRINT TAB(4,16) "PRESS SPACE"
320REPEAT UNTIL INKEY(-99)
330UNTIL FALSE


The post Learn to write games for the BBC Micro with Eben appeared first on Raspberry Pi.

Coolest Projects International 2018

via Raspberry Pi

Like many engineers, I have folder upon folder of half-completed projects on my computer. But the funny thing is that this wasn’t a problem for me as a child. Every other Friday evening, I’d spend two hours at Ilkley Computer Club, where I could show off whatever I’d been working on: nothing motivates you to actually finish a project like the opportunity to share it with an audience.

Raspberry Jams, Code Clubs, and CoderDojos all provide children (of all ages: we’re looking at you, Peter Onion) with a place where they can learn, share ideas, and make cool stuff with code and computers. But you can get so involved with the things you’re working on that you forget to take a step back every once in a while to look at what you’ve accomplished. And what do you do when you’ve shown your project to everyone you know, and you fancy a shot at a slightly larger audience?

Enter Coolest Projects International, now in its seventh year. Here’s a video that captures about 1% of the awesomeness of being there in person.

Celebrating Coolest Projects International 2018

Coolest Projects is a world-leading showcase that empowers and inspires the next generation of digital creators, innovators, changemakers, and entrepreneurs. This year, for the first time, we brought Coolest Projects to the UK for a spectacular regional event in London!

Coolest Projects brings Ninjas from CoderDojos across the globe together in Dublin for a chance to share their work with the world, and to compete to be coolest in one of several categories:

  • Scratch projects
  • Websites
  • Games
  • Mobile apps
  • Hardware
  • Evolution (basically, next-level stuff)

At this year’s event, more than 1000 children presented projects, from 15 countries including Argentina, Bulgaria, Italy, Japan, Romania, and Spain.

Raspberry Pi on Twitter

This is it! #CoolestProjects https://t.co/eoepjNWLsC

And for the first time, Coolest Projects was open to Raspberry Jam and Code Club members, and to the broader Raspberry Pi community.

Liz, our daughter Aphra, and I spent the day at the event, along with the CoderDojo team, what felt like half the Raspberry Pi Foundation, keynote speaker Pete Lomas, and the most amazing army of volunteers. Between chugging slushies, I had the opportunity to judge hardware projects with Noel King, CoderDojo volunteer and co-founder of Coolest Projects. Noel provided the judges with a pep talk at the start of the day. He reminded us that the aim wasn’t necessarily to find the most complete, or polished, or technically audacious project, but to seek out creativity: the project that does something unique, or does something you’ve seen before but in a unique way.

To my mind, the focus on creativity is what sets Coolest Projects apart. This is, after all, a contest that aims to “empower and inspire the next generation of digital creators, innovators, changemakers, and entrepreneurs”, and that recognises that each of those activities is, at heart, a creative pursuit.

Unsurprisingly, given the strength of the field, judging went on for some time. Each category’s winner and runner-up were exceptional, and there were countless other projects that didn’t quite make the cut but that I’d be proud to have made myself. Where were these folks when I was a teenager?

You can see the winners and runners up in each category on the Coolest Projects Twitter feed, and you should also check out the winners of the six special prizes. One that especially struck me was Selin Alara Ornek’s project, iC4U, a robot guide dog that she developed at her local CoderDojo in Turkey.

While Coolest Projects started in Dublin, it’s now an international phenomenon. In the last couple of months we’ve seen Coolest Projects regional events in Belgium, Romania, and the UK.

Showcasing your projects at Coolest Projects UK 2018

Coolest Projects is a world-leading showcase that empowers and inspires the next generation of digital creators, innovators, changemakers, and entrepreneurs. This year, for the first time, we brought Coolest Projects to the UK for a spectacular regional event in London!

In September we’ll be holding the inaugural Coolest Projects North America at the Discovery Cube in Orange County.

Coolest Projects began as a volunteer-run event, and we’re immensely privileged to have this wonderful showcase for our community. We are enormously grateful to all the staff and volunteers who continue to give huge amounts of their time, effort, and talent every year to make it the wonderful event that it is. Thank you, all of you.

Events like these give me hope that the future of our industry will be every bit as exciting, and vastly more diverse, than our past and present. If you have a chance to participate in one of them, I think you’ll come away feeling the same.

The post Coolest Projects International 2018 appeared first on Raspberry Pi.

Raspberry Pi 3 Model B+ on sale now at $35

via Raspberry Pi

Here’s a long post. We think you’ll find it interesting. If you don’t have time to read it all, we recommend you watch this video, which will fill you in with everything you need, and then head straight to the product page to fill yer boots. (We recommend the video anyway, even if you do have time for a long read. ‘Cos it’s fab.)

A BRAND-NEW PI FOR π DAY

Raspberry Pi 3 Model B+ is now on sale now for $35, featuring: – A 1.4GHz 64-bit quad-core ARM Cortex-A53 CPU – Dual-band 802.11ac wireless LAN and Bluetooth 4.2 – Faster Ethernet (Gigabit Ethernet over USB 2.0) – Power-over-Ethernet support (with separate PoE HAT) – Improved PXE network and USB mass-storage booting – Improved thermal management Alongside a 200MHz increase in peak CPU clock frequency, we have roughly three times the wired and wireless network throughput, and the ability to sustain high performance for much longer periods.

If you’ve been a Raspberry Pi watcher for a while now, you’ll have a bit of a feel for how we update our products. Just over two years ago, we released Raspberry Pi 3 Model B. This was our first 64-bit product, and our first product to feature integrated wireless connectivity. Since then, we’ve sold over nine million Raspberry Pi 3 units (we’ve sold 19 million Raspberry Pis in total), which have been put to work in schools, homes, offices and factories all over the globe.

Those Raspberry Pi watchers will know that we have a history of releasing improved versions of our products a couple of years into their lives. The first example was Raspberry Pi 1 Model B+, which added two additional USB ports, introduced our current form factor, and rolled up a variety of other feedback from the community. Raspberry Pi 2 didn’t get this treatment, of course, as it was superseded after only one year; but it feels like it’s high time that Raspberry Pi 3 received the “plus” treatment.

So, without further ado, Raspberry Pi 3 Model B+ is now on sale for $35 (the same price as the existing Raspberry Pi 3 Model B), featuring:

  • A 1.4GHz 64-bit quad-core ARM Cortex-A53 CPU
  • Dual-band 802.11ac wireless LAN and Bluetooth 4.2
  • Faster Ethernet (Gigabit Ethernet over USB 2.0)
  • Power-over-Ethernet support (with separate PoE HAT)
  • Improved PXE network and USB mass-storage booting
  • Improved thermal management

Alongside a 200MHz increase in peak CPU clock frequency, we have roughly three times the wired and wireless network throughput, and the ability to sustain high performance for much longer periods.

Behold the shiny

Raspberry Pi 3B+ is available to buy today from our network of Approved Resellers.

New features, new chips

Roger Thornton did the design work on this revision of the Raspberry Pi. Here, he and I have a chat about what’s new.

Introducing the Raspberry Pi 3 Model B+

Raspberry Pi 3 Model B+ is now on sale now for $35, featuring: – A 1.4GHz 64-bit quad-core ARM Cortex-A53 CPU – Dual-band 802.11ac wireless LAN and Bluetooth 4.2 – Faster Ethernet (Gigabit Ethernet over USB 2.0) – Power-over-Ethernet support (with separate PoE HAT) – Improved PXE network and USB mass-storage booting – Improved thermal management Alongside a 200MHz increase in peak CPU clock frequency, we have roughly three times the wired and wireless network throughput, and the ability to sustain high performance for much longer periods.

The new product is built around BCM2837B0, an updated version of the 64-bit Broadcom application processor used in Raspberry Pi 3B, which incorporates power integrity optimisations, and a heat spreader (that’s the shiny metal bit you can see in the photos). Together these allow us to reach higher clock frequencies (or to run at lower voltages to reduce power consumption), and to more accurately monitor and control the temperature of the chip.

Dual-band wireless LAN and Bluetooth are provided by the Cypress CYW43455 “combo” chip, connected to a Proant PCB antenna similar to the one used on Raspberry Pi Zero W. Compared to its predecessor, Raspberry Pi 3B+ delivers somewhat better performance in the 2.4GHz band, and far better performance in the 5GHz band, as demonstrated by these iperf results from LibreELEC developer Milhouse.

Tx bandwidth (Mb/s) Rx bandwidth (Mb/s)
Raspberry Pi 3B 35.7 35.6
Raspberry Pi 3B+ (2.4GHz) 46.7 46.3
Raspberry Pi 3B+ (5GHz) 102 102

The wireless circuitry is encapsulated under a metal shield, rather fetchingly embossed with our logo. This has allowed us to certify the entire board as a radio module under FCC rules, which in turn will significantly reduce the cost of conformance testing Raspberry Pi-based products.

We’ll be teaching metalwork next.

Previous Raspberry Pi devices have used the LAN951x family of chips, which combine a USB hub and 10/100 Ethernet controller. For Raspberry Pi 3B+, Microchip have supported us with an upgraded version, LAN7515, which supports Gigabit Ethernet. While the USB 2.0 connection to the application processor limits the available bandwidth, we still see roughly a threefold increase in throughput compared to Raspberry Pi 3B. Again, here are some typical iperf results.

Tx bandwidth (Mb/s) Rx bandwidth (Mb/s)
Raspberry Pi 3B 94.1 95.5
Raspberry Pi 3B+ 315 315

We use a magjack that supports Power over Ethernet (PoE), and bring the relevant signals to a new 4-pin header. We will shortly launch a PoE HAT which can generate the 5V necessary to power the Raspberry Pi from the 48V PoE supply.

There… are… four… pins!

Coming soon to a Raspberry Pi 3B+ near you

Raspberry Pi 3B was our first product to support PXE Ethernet boot. Testing it in the wild shook out a number of compatibility issues with particular switches and traffic environments. Gordon has rolled up fixes for all known issues into the BCM2837B0 boot ROM, and PXE boot is now enabled by default.

Clocking, voltages and thermals

The improved power integrity of the BCM2837B0 package, and the improved regulation accuracy of our new MaxLinear MxL7704 power management IC, have allowed us to tune our clocking and voltage rules for both better peak performance and longer-duration sustained performance.

Below 70°C, we use the improvements to increase the core frequency to 1.4GHz. Above 70°C, we drop to 1.2GHz, and use the improvements to decrease the core voltage, increasing the period of time before we reach our 80°C thermal throttle; the reduction in power consumption is such that many use cases will never reach the throttle. Like a modern smartphone, we treat the thermal mass of the device as a resource, to be spent carefully with the goal of optimising user experience.

This graph, courtesy of Gareth Halfacree, demonstrates that Raspberry Pi 3B+ runs faster and at a lower temperature for the duration of an eight‑minute quad‑core Sysbench CPU test.

Note that Raspberry Pi 3B+ does consume substantially more power than its predecessor. We strongly encourage you to use a high-quality 2.5A power supply, such as the official Raspberry Pi Universal Power Supply.

FAQs

We’ll keep updating this list over the next couple of days, but here are a few to get you started.

Are you discontinuing earlier Raspberry Pi models?

No. We have a lot of industrial customers who will want to stick with the existing products for the time being. We’ll keep building these models for as long as there’s demand. Raspberry Pi 1B+, Raspberry Pi 2B, and Raspberry Pi 3B will continue to sell for $25, $35, and $35 respectively.

What about Model A+?

Raspberry Pi 1A+ continues to be the $20 entry-level “big” Raspberry Pi for the time being. We are considering the possibility of producing a Raspberry Pi 3A+ in due course.

What about the Compute Module?

CM1, CM3 and CM3L will continue to be available. We may offer versions of CM3 and CM3L with BCM2837B0 in due course, depending on customer demand.

Are you still using VideoCore?

Yes. VideoCore IV 3D is the only publicly-documented 3D graphics core for ARM‑based SoCs, and we want to make Raspberry Pi more open over time, not less.

Credits

A project like this requires a vast amount of focused work from a large team over an extended period. Particular credit is due to Roger Thornton, who designed the board and ran the exhaustive (and exhausting) RF compliance campaign, and to the team at the Sony UK Technology Centre in Pencoed, South Wales. A partial list of others who made major direct contributions to the BCM2837B0 chip program, CYW43455 integration, LAN7515 and MxL7704 developments, and Raspberry Pi 3B+ itself follows:

James Adams, David Armour, Jonathan Bell, Maria Blazquez, Jamie Brogan-Shaw, Mike Buffham, Rob Campling, Cindy Cao, Victor Carmon, KK Chan, Nick Chase, Nigel Cheetham, Scott Clark, Nigel Clift, Dominic Cobley, Peter Coyle, John Cronk, Di Dai, Kurt Dennis, David Doyle, Andrew Edwards, Phil Elwell, John Ferdinand, Doug Freegard, Ian Furlong, Shawn Guo, Philip Harrison, Jason Hicks, Stefan Ho, Andrew Hoare, Gordon Hollingworth, Tuomas Hollman, EikPei Hu, James Hughes, Andy Hulbert, Anand Jain, David John, Prasanna Kerekoppa, Shaik Labeeb, Trevor Latham, Steve Le, David Lee, David Lewsey, Sherman Li, Xizhe Li, Simon Long, Fu Luo Larson, Juan Martinez, Sandhya Menon, Ben Mercer, James Mills, Max Passell, Mark Perry, Eric Phiri, Ashwin Rao, Justin Rees, James Reilly, Matt Rowley, Akshaye Sama, Ian Saturley, Serge Schneider, Manuel Sedlmair, Shawn Shadburn, Veeresh Shivashimper, Graham Smith, Ben Stephens, Mike Stimson, Yuree Tchong, Stuart Thomson, John Wadsworth, Ian Watch, Sarah Williams, Jason Zhu.

If you’re not on this list and think you should be, please let me know, and accept my apologies.

The post Raspberry Pi 3 Model B+ on sale now at $35 appeared first on Raspberry Pi.

Happy birthday to us!

via Raspberry Pi

The eagle-eyed among you may have noticed that today is 28 February, which is as close as you’re going to get to our sixth birthday, given that we launched on a leap day. For the last three years, we’ve launched products on or around our birthday: Raspberry Pi 2 in 2015; Raspberry Pi 3 in 2016; and Raspberry Pi Zero W in 2017. But today is a snow day here at Pi Towers, so rather than launching something, we’re taking a photo tour of the last six years of Raspberry Pi products before we don our party hats for the Raspberry Jam Big Birthday Weekend this Saturday and Sunday.

Prehistory

Before there was Raspberry Pi, there was the Broadcom BCM2763 ‘micro DB’, designed, as it happens, by our very own Roger Thornton. This was the first thing we demoed as a Raspberry Pi in May 2011, shown here running an ARMv6 build of Ubuntu 9.04.

BCM2763 micro DB

Ubuntu on Raspberry Pi, 2011-style

A few months later, along came the first batch of 50 “alpha boards”, designed for us by Broadcom. I used to have a spreadsheet that told me where in the world each one of these lived. These are the first “real” Raspberry Pis, built around the BCM2835 application processor and LAN9512 USB hub and Ethernet adapter; remarkably, a software image taken from the download page today will still run on them.

Raspberry Pi alpha board, top view

Raspberry Pi alpha board

We shot some great demos with this board, including this video of Quake III:

Raspberry Pi – Quake 3 demo

A little something for the weekend: here’s Eben showing the Raspberry Pi running Quake 3, and chatting a bit about the performance of the board. Thanks to Rob Bishop and Dave Emett for getting the demo running.

Pete spent the second half of 2011 turning the alpha board into a shippable product, and just before Christmas we produced the first 20 “beta boards”, 10 of which were sold at auction, raising over £10000 for the Foundation.

The beginnings of a Bramble

Beta boards on parade

Here’s Dom, demoing both the board and his excellent taste in movie trailers:

Raspberry Pi Beta Board Bring up

See http://www.raspberrypi.org/ for more details, FAQ and forum.

Launch

Rather to Pete’s surprise, I took his beta board design (with a manually-added polygon in the Gerbers taking the place of Paul Grant’s infamous red wire), and ordered 2000 units from Egoman in China. After a few hiccups, units started to arrive in Cambridge, and on 29 February 2012, Raspberry Pi went on sale for the first time via our partners element14 and RS Components.

Pallet of pis

The first 2000 Raspberry Pis

Unboxing continues

The first Raspberry Pi from the first box from the first pallet

We took over 100000 orders on the first day: something of a shock for an organisation that had imagined in its wildest dreams that it might see lifetime sales of 10000 units. Some people who ordered that day had to wait until the summer to finally receive their units.

Evolution

Even as we struggled to catch up with demand, we were working on ways to improve the design. We quickly replaced the USB polyfuses in the top right-hand corner of the board with zero-ohm links to reduce IR drop. If you have a board with polyfuses, it’s a real limited edition; even more so if it also has Hynix memory. Pete’s “rev 2” design made this change permanent, tweaked the GPIO pin-out, and added one much-requested feature: mounting holes.

Revision 1 versus revision 2

If you look carefully, you’ll notice something else about the revision 2 board: it’s made in the UK. 2012 marked the start of our relationship with the Sony UK Technology Centre in Pencoed, South Wales. In the five years since, they’ve built every product we offer, including more than 12 million “big” Raspberry Pis and more than one million Zeros.

Celebrating 500,000 Welsh units, back when that seemed like a lot

Economies of scale, and the decline in the price of SDRAM, allowed us to double the memory capacity of the Model B to 512MB in the autumn of 2012. And as supply of Model B finally caught up with demand, we were able to launch the Model A, delivering on our original promise of a $25 computer.

A UK-built Raspberry Pi Model A

In 2014, James took all the lessons we’d learned from two-and-a-bit years in the market, and designed the Model B+, and its baby brother the Model A+. The Model B+ established the form factor for all our future products, with a 40-pin extended GPIO connector, four USB ports, and four mounting holes.

The Raspberry Pi 1 Model B+ — entering the era of proper product photography with a bang.

New toys

While James was working on the Model B+, Broadcom was busy behind the scenes developing a follow-on to the BCM2835 application processor. BCM2836 samples arrived in Cambridge at 18:00 one evening in April 2014 (chips never arrive at 09:00 — it’s always early evening, usually just before a public holiday), and within a few hours Dom had Raspbian, and the usual set of VideoCore multimedia demos, up and running.

We launched Raspberry Pi 2 at the start of 2015, pairing BCM2836 with 1GB of memory. With a quad-core Arm Cortex-A7 clocked at 900MHz, we’d increased performance sixfold, and memory fourfold, in just three years.

Nobody mention the zenon death flash.

And of course, while James was working on Raspberry Pi 2, Broadcom was developing BCM2837, with a quad-core 64-bit Arm Cortex-A53 clocked at 1.2GHz. Raspberry Pi 3 launched barely a year after Raspberry Pi 2, providing a further doubling of performance and, for the first time, wireless LAN and Bluetooth.

All our recent products are just the same board shot from different angles

Zero to hero

Where the PC industry has historically used Moore’s Law to “fill up” a given price point with more performance each year, the original Raspberry Pi used Moore’s law to deliver early-2000s PC performance at a lower price. But with Raspberry Pi 2 and 3, we’d gone back to filling up our original $35 price point. After the launch of Raspberry Pi 2, we started to wonder whether we could pull the same trick again, taking the original Raspberry Pi platform to a radically lower price point.

The result was Raspberry Pi Zero. Priced at just $5, with a 1GHz BCM2835 and 512MB of RAM, it was cheap enough to bundle on the front of The MagPi, making us the first computer magazine to give away a computer as a cover gift.

Cheap thrills

MagPi issue 40 in all its glory

We followed up with the $10 Raspberry Pi Zero W, launched exactly a year ago. This adds the wireless LAN and Bluetooth functionality from Raspberry Pi 3, using a rather improbable-looking PCB antenna designed by our buddies at Proant in Sweden.

Up to our old tricks again

Other things

Of course, this isn’t all. There has been a veritable blizzard of point releases; RAM changes; Chinese red units; promotional blue units; Brazilian blue-ish units; not to mention two Camera Modules, in two flavours each; a touchscreen; the Sense HAT (now aboard the ISS); three compute modules; and cases for the Raspberry Pi 3 and the Zero (the former just won a Design Effectiveness Award from the DBA). And on top of that, we publish three magazines (The MagPi, Hello World, and HackSpace magazine) and a whole host of Project Books and Essentials Guides.

Chinese Raspberry Pi 1 Model B

RS Components limited-edition blue Raspberry Pi 1 Model B

Brazilian-market Raspberry Pi 3 Model B

Visible-light Camera Module v2

Learning about injection moulding the hard way

250 pages of content each month, every month

Essential reading

Forward the Foundation

Why does all this matter? Because we’re providing everyone, everywhere, with the chance to own a general-purpose programmable computer for the price of a cup of coffee; because we’re giving people access to tools to let them learn new skills, build businesses, and bring their ideas to life; and because when you buy a Raspberry Pi product, every penny of profit goes to support the Raspberry Pi Foundation in its mission to change the face of computing education.

We’ve had an amazing six years, and they’ve been amazing in large part because of the community that’s grown up alongside us. This weekend, more than 150 Raspberry Jams will take place around the world, comprising the Raspberry Jam Big Birthday Weekend.

Raspberry Pi Big Birthday Weekend 2018. GIF with confetti and bopping JAM balloons

If you want to know more about the Raspberry Pi community, go ahead and find your nearest Jam on our interactive map — maybe we’ll see you there.

The post Happy birthday to us! appeared first on Raspberry Pi.

Why Raspberry Pi isn’t vulnerable to Spectre or Meltdown

via Raspberry Pi

Over the last couple of days, there has been a lot of discussion about a pair of security vulnerabilities nicknamed Spectre and Meltdown. These affect all modern Intel processors, and (in the case of Spectre) many AMD processors and ARM cores. Spectre allows an attacker to bypass software checks to read data from arbitrary locations in the current address space; Meltdown allows an attacker to read arbitrary data from the operating system kernel’s address space (which should normally be inaccessible to user programs).

Both vulnerabilities exploit performance features (caching and speculative execution) common to many modern processors to leak data via a so-called side-channel attack. Happily, the Raspberry Pi isn’t susceptible to these vulnerabilities, because of the particular ARM cores that we use.

To help us understand why, here’s a little primer on some concepts in modern processor design. We’ll illustrate these concepts using simple programs in Python syntax like this one:

t = a+b
u = c+d
v = e+f
w = v+g
x = h+i
y = j+k

While the processor in your computer doesn’t execute Python directly, the statements here are simple enough that they roughly correspond to a single machine instruction. We’re going to gloss over some details (notably pipelining and register renaming) which are very important to processor designers, but which aren’t necessary to understand how Spectre and Meltdown work.

For a comprehensive description of processor design, and other aspects of modern computer architecture, you can’t do better than Hennessy and Patterson’s classic Computer Architecture: A Quantitative Approach.

What is a scalar processor?

The simplest sort of modern processor executes one instruction per cycle; we call this a scalar processor. Our example above will execute in six cycles on a scalar processor.

Examples of scalar processors include the Intel 486 and the ARM1176 core used in Raspberry Pi 1 and Raspberry Pi Zero.

What is a superscalar processor?

The obvious way to make a scalar processor (or indeed any processor) run faster is to increase its clock speed. However, we soon reach limits of how fast the logic gates inside the processor can be made to run; processor designers therefore quickly began to look for ways to do several things at once.

An in-order superscalar processor examines the incoming stream of instructions and tries execute more than one at once, in one of several “pipes”, subject to dependencies between the instructions. Dependencies are important: you might think that a two-way superscalar processor could just pair up (or dual-issue) the six instructions in our example like this:

t, u = a+b, c+d
v, w = e+f, v+g
x, y = h+i, j+k

But this doesn’t make sense: we have to compute v before we can compute w, so the third and fourth instructions can’t be executed at the same time. Our two-way superscalar processor won’t be able to find anything to pair with the third instruction, so our example will execute in four cycles:

t, u = a+b, c+d
v    = e+f                   # second pipe does nothing here
w, x = v+g, h+i
y    = j+k

Examples of superscalar processors include the Intel Pentium, and the ARM Cortex-A7 and Cortex-A53 cores used in Raspberry Pi 2 and Raspberry Pi 3 respectively. Raspberry Pi 3 has only a 33% higher clock speed than Raspberry Pi 2, but has roughly double the performance: the extra performance is partly a result of Cortex-A53’s ability to dual-issue a broader range of instructions than Cortex-A7.

What is an out-of-order processor?

Going back to our example, we can see that, although we have a dependency between v and w, we have other independent instructions later in the program that we could potentially have used to fill the empty pipe during the second cycle. An out-of-order superscalar processor has the ability to shuffle the order of incoming instructions (again subject to dependencies) in order to keep its pipelines busy.

An out-of-order processor might effectively swap the definitions of w and x in our example like this:

t = a+b
u = c+d
v = e+f
x = h+i
w = v+g
y = j+k

allowing it to execute in three cycles:

t, u = a+b, c+d
v, x = e+f, h+i
w, y = v+g, j+k

Examples of out-of-order processors include the Intel Pentium 2 (and most subsequent Intel and AMD x86 processors), and many recent ARM cores, including Cortex-A9, -A15, -A17, and -A57.

What is speculation?

Reordering sequential instructions is a powerful way to recover more instruction-level parallelism, but as processors become wider (able to triple- or quadruple-issue instructions) it becomes harder to keep all those pipes busy. Modern processors have therefore grown the ability to speculate. Speculative execution lets us issue instructions which might turn out not to be required (because they are branched over): this keeps a pipe busy, and if it turns out that the instruction isn’t executed, we can just throw the result away.

To demonstrate the benefits of speculation, let’s look at another example:

t = a+b
u = t+c
v = u+d
if v:
   w = e+f
   x = w+g
   y = x+h

Now we have dependencies from t to u to v, and from w to x to y, so a two-way out-of-order processor without speculation won’t ever be able to fill its second pipe. It spends three cycles computing t, u, and v, after which it knows whether the body of the if statement will execute, in which case it then spends three cycles computing w, x, and y. Assuming the if (a branch instruction) takes one cycle, our example takes either four cycles (if v turns out to be zero) or seven cycles (if v is non-zero).

Speculation effectively shuffles the program like this:

t = a+b
u = t+c
v = u+d
w_ = e+f
x_ = w_+g
y_ = x_+h
if v:
   w, x, y = w_, x_, y_

so we now have additional instruction level parallelism to keep our pipes busy:

t, w_ = a+b, e+f
u, x_ = t+c, w_+g
v, y_ = u+d, x_+h
if v:
   w, x, y = w_, x_, y_

Cycle counting becomes less well defined in speculative out-of-order processors, but the branch and conditional update of w, x, and y are (approximately) free, so our example executes in (approximately) three cycles.

What is a cache?

In the good old days*, the speed of processors was well matched with the speed of memory access. My BBC Micro, with its 2MHz 6502, could execute an instruction roughly every 2µs (microseconds), and had a memory cycle time of 0.25µs. Over the ensuing 35 years, processors have become very much faster, but memory only modestly so: a single Cortex-A53 in a Raspberry Pi 3 can execute an instruction roughly every 0.5ns (nanoseconds), but can take up to 100ns to access main memory.

At first glance, this sounds like a disaster: every time we access memory, we’ll end up waiting for 100ns to get the result back. In this case, this example:

a = mem[0]
b = mem[1]

would take 200ns.

In practice, programs tend to access memory in relatively predictable ways, exhibiting both temporal locality (if I access a location, I’m likely to access it again soon) and spatial locality (if I access a location, I’m likely to access a nearby location soon). Caching takes advantage of these properties to reduce the average cost of access to memory.

A cache is a small on-chip memory, close to the processor, which stores copies of the contents of recently used locations (and their neighbours), so that they are quickly available on subsequent accesses. With caching, the example above will execute in a little over 100ns:

a = mem[0]    # 100ns delay, copies mem[0:15] into cache
b = mem[1]    # mem[1] is in the cache

From the point of view of Spectre and Meltdown, the important point is that if you can time how long a memory access takes, you can determine whether the address you accessed was in the cache (short time) or not (long time).

What is a side channel?

From Wikipedia:

“… a side-channel attack is any attack based on information gained from the physical implementation of a cryptosystem, rather than brute force or theoretical weaknesses in the algorithms (compare cryptanalysis). For example, timing information, power consumption, electromagnetic leaks or even sound can provide an extra source of information, which can be exploited to break the system.”

Spectre and Meltdown are side-channel attacks which deduce the contents of a memory location which should not normally be accessible by using timing to observe whether another location is present in the cache.

Putting it all together

Now let’s look at how speculation and caching combine to permit the Meltdown attack. Consider the following example, which is a user program that sometimes reads from an illegal (kernel) address:

t = a+b
u = t+c
v = u+d
if v:
   w = kern_mem[address]   # if we get here crash
   x = w&0x100
   y = user_mem[x]

Now our out-of-order two-way superscalar processor shuffles the program like this:

t, w_ = a+b, kern_mem[address]
u, x_ = t+c, w_&0x100
v, y_ = u+d, user_mem[x_]

if v:
   # crash
   w, x, y = w_, x_, y_      # we never get here

Even though the processor always speculatively reads from the kernel address, it must defer the resulting fault until it knows that v was non-zero. On the face of it, this feels safe because either:

  • v is zero, so the result of the illegal read isn’t committed to w
  • v is non-zero, so the program crashes before the read is committed to w

However, suppose we flush our cache before executing the code, and arrange a, b, c, and d so that v is zero. Now, the speculative load in the third cycle:

v, y_ = u+d, user_mem[x_]

will read from either address 0x000 or address 0x100 depending on the eighth bit of the result of the illegal read. Because v is zero, the results of the speculative instructions will be discarded, and execution will continue. If we time a subsequent access to one of those addresses, we can determine which address is in the cache. Congratulations: you’ve just read a single bit from the kernel’s address space!

The real Meltdown exploit is more complex than this, but the principle is the same. Spectre uses a similar approach to subvert software array bounds checks.

Conclusion

Modern processors go to great lengths to preserve the abstraction that they are in-order scalar machines that access memory directly, while in fact using a host of techniques including caching, instruction reordering, and speculation to deliver much higher performance than a simple processor could hope to achieve. Meltdown and Spectre are examples of what happens when we reason about security in the context of that abstraction, and then encounter minor discrepancies between the abstraction and reality.

The lack of speculation in the ARM1176, Cortex-A7, and Cortex-A53 cores used in Raspberry Pi render us immune to attacks of the sort.

* days may not be that old, or that good

The post Why Raspberry Pi isn’t vulnerable to Spectre or Meltdown appeared first on Raspberry Pi.