Raspberry Pi has long been the gold standard for inexpensive single-board computing, powering everything from robots to smart home devices to digital kiosks. The Raspberry Pi 4 takes Pi to another level, with performance that’s good enough to use in a pinch as a desktop PC, plus the ability to output 4K video at 60 Hz or power dual monitors.
For the same $35 starting price as prior models, you get speeds that are two to four times faster, support for USB 3 and true Gigabit Ethernet. Perhaps more importantly, there is a $45 Raspberry Pi 4 with 2GB of RAM and a $55 unit with 4GB, four times more than any previous Pi has had. Makers and hobbyists should add the Raspberry Pi 4 to their arsenals, and tech enthusiasts who’ve never used a Pi before now have even more reasons to buy one.
We had did extensive testing on the Raspberry Pi 4 B, the full name of the first Pi 4 model, and were able to benchmark a board with 4GB of RAM. What we saw is a full-fledged mini computer that’s packed with potential. We’re particularly excited about the possibilities for inference, particularly object and sound detection.
While there were some apps that needed updating at launch time, almost everything that ran on the Pi 3 B works on the Raspberry Pi 4 B. If you have old microSD cards from a prior Pi build, they may not work, because the Pi 4 B requires Raspbian Buster, the lastest version of the platform's official OS. Support from other operating systems such as Ubuntu has also improved.
However, game emulation is still flagging a bit (see below). And because of the subtle differences in the design (dual microHDMI ports, USB-C power), any case that was designed to hold the Pi 3 B will not fit.
Game Emulation or Lack Thereof
Nearly five months after launch, Retropie, the very popular gaming emulator software, does not officially support the Raspberry Pi 4 out of the box. There's a workaround that allows you to install and use Retropie on a Raspberry Pi 4, but it's not officially supported and it takes some time to do.
Lakka, an alternative to Retropie, now does officially support the Pi 4. However, this emulation platform isn't as full-featured or attractive as Retropie.
The table below shows a key specs comparison between the Raspberry Pi 4 B, the first an only Pi 4 model, and the Raspberry Pi 3B+, the fastest version of the Pi 3.
|Spec||Raspberry Pi 4 B||Raspberry Pi 3 B+|
|CPU||1.5-GHz, Quad-Core Broadcom BCM2711B0 (Cortex A-72)||1.4-GHz, Quad Core Broadcom BCM2837B0 (Cortex A-53)|
|RAM||1 - 4GB DDR4||1GB DDR2|
|GPU||500 MHz VideoCore VI||400 MHz VideoCore IV|
|Video Out||dual micro HDMI ports||single HDMI port|
|Max resolution||4K 60 Hz + 1080p or 2x 4K 30 Hz||2560 x 1600|
|USB Ports||2x USB 3.0 / 2x USB 2.0||4x USB 2.0|
|Wired Networking||Gigabit Ethernet||330 Mbps Ethernet|
|Wireless||802.11ac (2.4 / 5 GHz), Bluetooth 5.0||802.11ac (2.4 / 5 GHz), Bluetooth 4.1|
|Charging Port||USB Type-C||micro USB|
|Power Requirement||3A, 5V||2.5A, 5V|
|Size||3.5 x 2.3 x 0.76 inches (88 x 58 x 19.5mm)||3.2 x 2.2 x 0.76 inches (82 x 56 x 19.5mm)|
|Weight||0.1 pounds (46 grams)||0.11 pounds (50 grams)|
The most important new features are the faster processor and GPU, more and faster RAM, the addition of USB 3 ports, dual micro HDMI ports instead of a single HDMI connection and support for 4K output. The higher bus speed that enables USB 3 support also allows the on-board Ethernet port to support true Gigabit connections (125 MBps) where the last-gen models had a theoretical maximum of just 41 MBps. The microSD card slot is also twice as fast, offering a theoretical maximum of 50 MBps versus 25 MBps on the 3B+.
Because the new SoC needs more power, the Raspberry Pi 4 B charges over USB Type-C instead of micro USB. It also requires a power adapter that can deliver at least 3 amps of power and 5 volts, though you may be able to get away with 2.5 amps if you don’t attach many peripherals to the USB ports. Putting aside the power needs, USB Type-C connectors are reversible, which makes them much easier for kids (and adults) to plug in.
After we first published this review, we found out that some USB Type-C cables don't work with the Raspberry Pi 4. Those cables that are "electronically marked" will see the Pi 4 as a USB audio device and not provide power. Only USB-C to USB-C cables can be electronically marked and you only find this on cables that operate at 5 Gbps or higher. In our tests, we found 11 low-cost USB-C cables that work with the Raspberry Pi 4 and only found a few cables, all USB 3.1, that did not. If you buy Raspberry Pi's official Pi 4 charger, which comes with a cable, you also won't have a problem. The Pi foundation says it will fix the problem on future builds, but it can't be solved via a firmware update.
At 3.5 x 2.3 x 0.76 inches (88 x 58 x 19.5 mm) and 0.1 pounds (46 grams), the Pi 4 is thin enough to fit in your pocket and light enough to carry anywhere. The board is durable enough to probably survive rolling around in your bag, but we recommend sticking it in something protective, mostly to protect the pins. However, during testing, I always used the board bare on my desk and I carried it back and forth between work and home many times by simply putting it in a cardboard box with no padding or static bag.
Unfortunately, if you want a case, you can’t use one that’s been designed for any previous Raspberry Pi. The Raspberry Pi 3 B / 3 B+ have almost the same dimensions, but the port layout has changed just enough to make the Pi 4 B incompatible. Where prior Pis had a single, full-size HDMI port, the dual micro HDMI connectors on the Pi 4 jut out more and so don’t line up with the holes on anything that was designed for the Pi 3 B. We really like the Pimoroni Pibow, a $10 / £8.50 case that looks really good and doesn't cover over the GPIO pins.
The Raspberry Pi 4 covers more than just the basics when it comes to ports. The right side has four USB Type-A connections, two of which are USB 3.0. There’s also a full-size, Gigabit Ethernet port for wired connections there. The bottom edge has a 3.5mm audio jack, two micro HDMI ports and the USB Type-C charging port. On the left side, you’ll find the microSD card reader.
And on the top surface of the board, you’ll see ribbon connectors for the Camera Serial Interface (CSI) and Display Serial Interface (DSI), which provide dedicated connections to Raspberry Pi’s own camera and screen (or compatible accessories). Of course, you can connect a camera to a USB port as well and there are a couple of more common ways, including the micro HDMI ports, to output to a screen.
New CPU, RAM
The Raspberry Pi 4 has similar design and dimensions to its predecessors, but it’s an all-new platform, powered by a new processor, the Broadcom BCM2711B0. Since the first Pi in 2012, all Pis have used 40nm SoCs, but this new chip is based on a 28nm process and, instead of the older Cortex-A53 microarchitecture, it uses Cortex-A72. The BCM2711B0 in the Raspberry Pi 4 has four cores and is clocked at 1.5 GHz, which at first blush, doesn’t seem much quicker than the quad-core, 1.4 GHz BCM2837B0 in the Raspberry Pi 3B+.
However, Cortex A72 has 15-instruction pipeline depth, compared to just 8 on the older model, and it also provides out-of-order execution so it’s not waiting for the output of one process to start on another. So, even at the same clock speed (and the BCM2711B0 is based on a smaller process node), Cortex-A72 processors will be significantly faster and use more power than their A53-powered ancestors.
For example, on the Linpack benchmark, which measures overall compute power, the Pi 4 absolutely whooped the Pi 3 B+ in all three tests. On the all-important single precision (SP) test, the Pi 4, scored 925 as compared to the 3 B+’s mark of 224, a boost of 413 percent.
On the Sysbench CPU test, the Pi 4 B was capable of performing 394 events per second as compared to 263 for the Pi 3 B+. That's a difference of 50 percent.
The RAM is also quite a bit quicker, going from 1GB of DDR2 RAM operating on the Pi 3B+ to up to 4GB of DDR4 RAM. In addition to the increased bandwidth, having more memory is a huge deal, particularly for web surfing.
The Pi 4’s RAM returned read and write rates of 4,130 and 4,427 Mbps, respectively. That’s 51 percent and 54 percent better than the 3 B+.
Both the CPU and the RAM are implicated when you do file compression. When zipping a file in multithreaded mode, the Pi 4 B is 37 percent quicker than its predecessor, but it’s far stronger in single-threaded, eclipsing the 3 B+ by 60 percent.
New GPU, Faster Graphics Performance
The GPU is getting a nice boost too. It moves from a Broadcom VideoCore IV that operated at a core clock speed of 400 MHz to a VideoCore VI that’s set at 500 MHz. The new architecture allows it to output to a display at up to 4K resolution with a rate of 60 fps or to support dual monitors at up to 4K 30 Hz.
While we wish we could have tried some of the more resource-intensive emulators in Retropie in time for this review, there wasn’t a Pi 4-compatible version at launch. However, the OpenArena Benchmark, which measures frame rates in a game that’s a a clone of Quake III Arena, did run.
At 720p resolution, the Pi 4 was the only Raspberry Pi capable of delivering smooth frame rates. Yes, you can play on the Pi 3, 3 A+ or 3 B+, but all three deliver rates between 27 and 28 fps as compared to 41.4 fps on the Pi 4.
No matter how fast your processor, RAM and GPU are, if your storage is slow, everyday tasks like opening apps and files will be laggy. Like all Raspberry Pis, the 4 B’s primary storage device is its microSD card reader, which is convenient but a bit constrained. According to the Pi Foundation, the 4 B has a top transfer rate of 50 MBps, which is double the speed of the reader on the 3 B+. There’s no known limit on capacity.
Our benchmarks, which were conducted with a Samsung EVO Plus microSD XC Class 10 card, show less impressive rates than the theoretical maximums. The Pi 4 B returned sequential read / write rates of 45.7 and 27.7 MBps, while the 3 B+ trailed at 22.8 and 17.5 MBps. Keep in mind that the card is rated for 100 MBps reads and 60 MBps writes.
If you have a speedy USB Flash drive or an external SSD, you can get far better storage performance out of the Pi 4 B. The Pi 4 B is the first with USB 3 ports, which have a maximum, theoretical bandwidth of 625 MBps. To find out how this works in real-life, we wrote a separate article where we attached an external SSD to a Raspberry Pi 4 B. You'll find full results in the article, but what we found was impressive.
Using a Western Digital Blue SSD in a USB to M.2 enclosure, we saw transfer rates that were 2 to 13x times faster than the microSD card. And applications definitely opened a lot faster with the SSD attached. Unfortunately, a regular USB Flash drive, was often slower than the microSD card.
However, it's important to note that, at present, the Pi 4 firmware doesn't allow you to boot off an external drive so the best that you can do is run all of your programs, including the majority of the OS, off of an SSD while leaving the boot partition on a microSD card. A firmware update should fix this in the next few weeks, but for now, we have an article explaining how to run your Raspberry Pi 4's software from an SSD.
Fast USB 3 ports are about more than just storage. You can use other high-bandwidth peripherals like Google’s Coral USB Accelerator, which helps with artificial intelligence tasks.
The Raspberry Pi 4 has the same 802.11ac Wi-Fi as its direct predecessor, but it throws in Bluetooth 5.0 support, an improvement over the Bluetooth 4 on prior models. More importantly, the Ethernet port now has more bandwidth, which allows it to offer a full gigabit of throughput where prior models could only achieve about 330 megabits.
In testing, the PI 4 B’s Ethernet port achieved 943 Mbps, which blows away the other Raspberry Pis. In fact, in a throughput test, the Pi 4 B got 943 Mbps (close to the 1,000 Mbps maximum). That’s nearly five times as many as the Pi 3B+, which only got 237 Mbps.
Both the old and new Raspberry Pi have 802.11ac Wi-Fi that can run on 2.4 GHz or 5-GHz bands. So we didn’t expect to see much difference in performance here. But the 5-GHz throughput is noticeably higher for the Pi 4, returning a rate of 114 Mbps, compared to 97 Mbps on the Pi 3 B+, a decent 18 percent improvement.
Power and Heat
With a more power-hungry processor and the need for at least a 5-volt, 3-amp power adapter, the Pi 4 should be expected to consume more power than its predecessors.
At idle, the Pi 4 B draws 3.4 watts, which is just 17 percent more than the 3 B+. Under load, that number jumps to 7.6 watts, but that’s still only 19 percent more juice than its direct predecessor. If you want the lowest-power Pi, performance be damned, then go for the Pi Zero W, which consumes a mere 0.8 watts at idle and 1.6 watts under load.
Yes, this board gets warm, warmer than its predecessor. Thermal images mirror what we experienced; the areas of the board near the CPU get really warm, not just the top of the processor itself. The Pi 4 board reaches a toasty 74.5 degrees Celsius (166 degrees Fahrenheit). That’s not enough for a serious burn, but kids especially should be sure to pick up the Pi by its sides only. The top surface of the Pi 3 B+ is much cooler, maxing out at 62.5 degrees Celsius (144.6 degrees Fahrenheit).
As with any modern computer, if you push the system too hard and the CPU or GPU get too hot, the computer will throttle down to avoid damage.
While running a CPU-intensive workload for 10 minutes, the processor hit 81 degrees and began throttling down from 1.5 to 1 GHz after 3 minutes. However, the system kept bringing itself back to the full 1.5 GHz when it dipped down to around 80 degrees, but then it would get warm again and go down to 1 GHz.
If you want to have better sustained performance under load, get an active cooler like the Pimoroni Fan Shim. In our tests, the Shim was so good that it allowed us to sustain an overclocked speed of 2,147 MHz.
The real star of the show on any Raspberry Pi is its set of 40 GPIO (General Input / Output) pins. The pin count and layout remains unchanged from prior models, going back to the Raspberry Pi 2, so any “hats,” sensors or LED screens that were made to attach to a Pi 2 or 3 will be compatible.
However, the Raspberry Pi 4 has added a few new capabilities to some of the pins. For hardcore makers who are wiring up a variety of peripherals, the GPIO pins now support four additional I2C, SPI and UART connections. So, if your sensors or peripherals require any of these interfaces, you now have a lot more of them.
Below, you'll find a new GPIO pinout, with the added capabilities of the Pi 4. To learn more about what each pin does, checkout our Raspberry Pi 4 GPIO pinout article.
The speed and responsiveness of the GPIO pins is also much faster on the Raspberry Pi 4, likely due to its faster processor. Our test uses the gpiozero Python library to toggle pins on and off continuously and measures the rate at which they switch. The Pi 4 achieved a speed of 50.8 KHz, compared to just 16.1 on the Pi 3 B+. That’s an improvement of 215%.
Using the Raspberry Pi 4 as a PC
One of the goals of the Raspberry Pi 4 is to be a capable PC that anyone can use for surfing the web, doing light productivity work or even playing very basic games. In order to test this use case, I spent several hours doing my everyday work on the device and I even wrote portions of this review using it.
I really liked being able to output to dual monitors, something I do everyday at both work and home. And, since much of my daily work routine these days takes place in a web browser, I had no problem writing, editing and researching articles using Chromium. Even with 15 tabs open, switching between them was smooth and I had not maxed out the 4GB of on-board RAM.
And while I wouldn’t want to use it every day, GIMP provides a decent way to edit still images. If I wanted to crunch spreadsheets or compose documents outside of Google Docs, Libre Office more than fits the bill.
My biggest problems involved video playback. If I wanted to watch a YouTube video, I had to keep it in a window, because even in 480p resolution, it was jerky at full screen. The other task I’d like to perform is playing retro games, but as of this writing, the Retropie package of emulators doesn’t work with Pi 4. I was able to install and play Quake Arena, however.
Keep in mind that the Raspberry Pi 4 works with a few different operating systems, but the best-supported one is Raspbian, a flavor of Linux that has a small learning curve for newbies. Users who are only looking for a low-cost web-surfing PC, without doing any tinkering, can find a Chromebook or low-end Windows laptop for $150 to $200.
4K Output, Video Playback and Transcoding
One of the downsides of prior Raspberry Pi computers is that they can only natively output to one screen at a time, but if you like multitasking and want to use a Pi for productivity, you really want that second screen. The Raspberry Pi 4 has dual micro HDMI ports that can each connect to a separate monitor or TV and can operate at up to 4K (3840 x 2160) resolution. If you have multiple 4K monitors, you have a choice: you can either run each screen at a somewhat-sluggish 30 Hz or, you can enable 4K mode in the settings menu, which jacks up the voltage a little so you can run one monitor at 4K 60 Hz and another at up to 1080p.
During extensive hands-on testing, I found that, while the 4K at 30 Hz is tolerable, little things like the movement of the mouse pointer are a bit sluggish. If you have a 4K screen, you’re definitely better off going for the 60 Hz mode, but note that the added voltage may also cause your CPU to get hot and throttle more easily.
While surfing the web, looking at still images and just enjoying all the extra screen real estate of 4K is great, video playback is the Raspberry Pi 4’s Achille’s heel, at least as of this writing. Whether we were attempting to stream a 4K video or use a downloaded file, we never got a smooth, workable 4K experience, either in Raspbian Buster or LibreElec, an OS that runs the Kodi media player. Several H.264 encoded videos, including Tears of Steel, did not play at all or showed as a jumble of colors. Even the sample jelly fish videos that the folks at Kodi recommended for my testing appeared as still pictures with no movement. Clearly, there’s a lot of optimization that still needs to be done both on the OS and software side to make the Raspberry Pi 4 capable of playing 4K video.
Unfortunately, even streaming 1080p YouTube videos is a challenge at this point. Running at 1080p resolution, full screen video trailer for Stranger Things showed obvious jerkiness. However, the playback was smooth when I watched the same clip in a smaller window. The same problem occurred, even when I dropped the stream’s resolution down to 480p.
Playing offline 1080p videos works well, provided your screen is at 1920 x 1080 or lower resolution. A downloaded trailer of Avenger’s Endgame was perfectly smooth when I watched it using the VLC player.
The Raspberry Pi 4 won’t replace anyone’s MacBook Pro or Dell XPS 13 creative workstation, but it can transcode videos for you, if you’re patient. It took the Raspberry Pi 4 48 seconds to transcode a very short H.264 encoded clip to NTSC DV format using FFmpeg. That’s much less time than the Pi 3 B+, which finished in 108 seconds, but if you’re converting a whole movie, you’ll probably need to walk away from your Pi for a while and then come back.
The web surfing experience on the Raspberry Pi 4 is noticeably much smoother than on any of its predecessors. The faster processor helps, but so does having more than 1GB of RAM. Keeping my eye on Gnome System Monitor, I noticed that, even with just one or two tabs open, I was using more than 1GB of RAM. However, on the Pi 4 with 4GB of RAM, I had no problem running over 15 tabs at once, switching back and forth between them.
While web pages don’t render as quickly as on my modern Core i7-powered laptop with Windows 10, the Pi 4 provides a very solid web browsing experience. I had no problems using my Google suite apps, including Gmail, Google Sheets and Google docs.
On Jetstream 1.1, a synthetic browsing benchmark that measures Javasript processing and page rendering, the Pi 4 trounced the Pi 3B+, 42.5 to 17.1 That’s an improvement of 148%, but the Pi still isn’t quite as powerful as a low-end, Intel-powered Chromebook like the Samsung Chromebook 3, which scored 49.7. However, there are PC laptops that fared worse, including the Dell Inspiron 14 3000, which hit just 35.9.
The Speedometer 2.0 benchmark measures overall responsiveness by loading dummy web apps and then simulating a user interacting with them. A higher score on this test, in terms of runs per minute, shows that when you’re actually using a web tool such as Google docs or Gmail, you should get less lag. As on Jetstream and in real-world scenarios, the Pi 4 came out comfortably ahead of its predecessor. In this case, it was 98 percent faster.
Just forget about using web sites with webGL animation on them, because they are slideshow like, at least with the current software. When I launched the webGL aquarium demo, which shows 50 fish swimming, I got a rate of just 2 fps on the Raspberry Pi 4 and a mere 1 fps on the Pi 3 B+. I guess that makes the Pi 4 twice as fast, but 2 fps is still useless.
It's very easy to use set up a Raspberry Pi web server and this is one of the most popular use cases for the computer. In fact, at Tom’s Hardware, we use a Raspberry Pi 3 B as a server on our local network that we use to host our laptop battery test. Raspberry Pi 4 promises even more robust web surfing thanks to its faster processor, greater amount of RAM and better network connectivity.
Using the Phoronix Apache Test, the Raspberry Pi 4 handled 3,983 requests per second versus 2,850 for the Pi 3 B+. That’s an improvement of 40 percent, which means that you can deliver heavier web pages or serve more visitors at the same time, without lag.
Many web applications use the PHP server-side scripting language so faster processing of PHP can help a lot. On PHPBench, which measures PHP performance, the Raspberry Pi 4 B scored 101,540, more than double the Pi 3 B+'s mark of 41,351.
A.I., Inference and Machine Learning
Perhaps the most exciting new use case for the Raspberry Pi 4 is for inference and machine learning. With the earlier Pis, you could already use a camera to do simple object detection at low frame rates, but the added performance and I/O from this new model should open up a whole new world of use cases.
To see how well the Pi 4 handles object detection, we followed the steps in this tutorial, which uses a combination of Google’s TensorFlow machine learning platform and OpenCV, a programming library that’s good for computer vision. After spending a good three hours compiling and installing all the software, I got the app running and watched as the webcam identified a few -- very few -- objects in my office, including sensing that I was a “person” and my chair was a “chair” with great confidence. It operated at a sluggish rate of 1.7 fps, but that’s 70 percent better than the 1 fps I got when running it on the Pi 3 B+.
However, with a more optimized framework, the Pi 4 should be able to do real-time facial and object recognition. And, because it has USB 3, an accelerator like the Google Coral TPU USB dongle should have much more bandwidth to send data back to the SoC. Imagine building a home companion robot that recognizes every member of your household by face or one that helps a farmer sort cucumbers by type. Some of these workloads are possible on earlier Raspberry Pi computers, but the Pi 4 B should make them fast and accurate enough to use on a regular basis. We can’t wait to see what developers and what makers do with Pi 4 and A.I.
Scikit-learn is a popular python module that enables machine learning. Performing a task in Scikit-learn was more than twice as quick on the Pi 4 B.
With Linux, you sometimes have to compile programs you want to install. Several times during our testing, we had to compile software packages, including when we wanted to get an object recognition demo going.
A speedier processor and better RAM help the Raspberry Pi 4 B compile code much faster than its predecessor. When we ran a test which compiles a Linux Kernel, the 4 B finished 33 percent faster. So, whether you're a developer who is writing your own software or just a user who wants a program that's not available as a direct download, the Pi 4 will save you time.
Overclocking the Pi 4
We’ve explained how to overclock the Raspberry Pi 4 and what kind of results you get in a separate article. However, the top line is that you can easily overclock the 1.5 GHz CPU over 2 GHz (in our case, up to 2,147 MHz). and increase the frequency of the GPU from 500 to 600 MHz without missing a beat. Just make sure that you have a fan like the Pimoroni Fan Shim.
How Much Raspberry Pi 4 RAM Do You Need?
The Raspberry Pi 4 B comes in three configurations, which are identical but for the amount of RAM. The $35 entry-level model has 1GB of RAM, the $45 unit has 2GB and the $55 SKU goes all the way to 4GB. One of the great advantages of all Raspberry Pis is that they are affordable enough to use in anything, so you need to choose wisely. If you are building a robot or other iOT device that just deals with motors and sensors, 1GB should be enough, because you aren’t running a slew of apps and you don’t even need the GUI.
We recommend 2GB if you’re doing very light web surfing, setting up a kiosk or deploying a limited-use web server. The 4GB model is ideal for using your Pi as a PC or for more complex tasks such as A.I.
The Raspberry Pi 4 represents a giant leap forward, not only for the Raspberry Pi, but for single-board computing. For the first time, it’s realistic to use your Pi as a secondary or backup PC (or perhaps a kids’ first PC). However, the larger real benefit will come not from folks who use Raspberry Pi 4s in lieu of x86 PCs, but from all the innovators who harness the system’s enhanced performance, I/O and graphics to create new iOT devices, media servers and robots. Kids building Pi projects in school will also have a world of new learning possibilities.
If you need a Raspberry Pi computer today for retro gaming, you’ll have to live with some issues that are likely to get resolved in the near future when Retropie gets official support. While it’s certain that major applications will be ported to the new computer, we still don’t know exactly how good video playback will get once the operating system is refined over time.
Despite these small issues , the Pi 4 stands head and shoulders above its predecessors and all the other inexpensive single board computers on the market. The main question isn’t: what can the Pi 4 do for you out of the box, but what can you make with it?
Editor’s Note: Some of the benchmarks in this article were performed by co-author Gareth Halfacree, who has posted his own, detailed analysis of Raspberry Pi 4 performance on Medium.
Image Credits: Tom's Hardware, Gareth Halfacree
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