Ubiquitous Unix Units

Plummeting hardware costs means afull-blown Unix system can be hadfor as little as $5.

This is part of my collection of tiny single-boardUnix systems, including a $5 Raspberry Pi and aNetgear router rescued from a Dumpster. Eachruns some version of Linux in as little as 32 MB ofmemory and 8 MB of nonvolatile flash.

Each of these relies on an ARM- or MIPS-basedSystem-on-Chip (SoC), which contains a proces-sor, cache, memory, and a variety of peripher-als such as Ethernet controllers, WiFi radios, andgraphics accelerators.

While ARM has captured the lion’s share of theembedded processor market (there is at least onein your cell phone), MIPS processors are still go-ing strong in consumer wireless routers, such asthe one you have at home.

All of these run Unix.

Raspberry Pi 3Model B$25

Broadcom BCM28371.2 GHz ARM Cortex A53 (Quad Core)1 GB LPDDR2-90032 GB SD card

Raspbian, based on Debian Linux

The Raspberry Pi is the king of the hobbyist sin-gle board Unix machines. Based on BroadcomSoCs intended for smartphones, over 19 millionPi’s have been sold since their debut in 2012 be-cause they are inexpensive, powerful, and well-supported.

While all Pi’s have included a graphics proces-sor an HDMI video, newer models include WiFiand Bluetooth.

Raspberry PiZero v1.3$5

Broadcom BCM28351 GHz ARM1176512 MB LPDDR28 GB SD card

Raspbian, based on Debian Linux

This is an extremely inexpensive, stripped-downversion of the Raspberry Pi that is neverthelessable to run a full graphical Unix environment.

This earlier version (2015) doesnot have WiFi or Ethernet; laterversions include WiFi.

The Raspberry Pi Zero was likelythe first Unix computer to havebeen given away with a magazine(MagPi 40, December 2015)

OnionOmega2+$13

MediaTek MT7688580 MHz 32-bit MIPS 24KEc128 MB DDR232 MB Flash

OpenWRT 18.06

Onion’s Omega computing module is based on aMIPS-based SoC intended for consumer wirelessrouters. It includes WiFi, Ethernet, and USB, butno video output.

It runs Onion’s variant of OpenWRT, a hobbyistLinux distribution designed for wireless routerswith minimal RAM and flash.

Orange PiZero H2$15

Allwinner H2+1.2 GHz ARM Cortex A7 (Quad Core)256 MB DDR32 GB SD Card

Debian Buster with Armbian

One of many Chinese Raspberry Pi knockoffs, theOrange Pi series ranges from this modest boardto 6-core low-end desktop replacements. All areable to run Raspberry Pi operating systems as wellas Android and others.

Armbian is a Debian Linux distribution tailoredto ARM development boards

Lichee PiNano H2$9

Allwinner F1C100s900 MHz ARM926-EJS32 MB DDR64 MB SD Card

OpenWRT 18.06

The Lichee Pi series is another Chinese RaspberryPi knockoff. The Nano is the smallest single-boardUnix computer in my collection, yet still supportsUSB, SD cards, and an LCD controller.

NexxWT3020HMini Router$17MediaTek MT7620N580 MHz MIPS 24KEc64 MB DDR8 MB Flash

OpenWRT 18.06

This small, inexpensive consumer wireless routercan nevertheless accommodate a reasonably pow-erful embedded Unix environment. Sporting oneof the many MIPS-based SoCs designed for con-sumer wireless routers, the Nexx has Wifi, twoEthernet ports, and USB.

I replaced the stock firmware with an Open-WRT image designed for this router and added aconnection to the serial debug console.

NetgearWNDR3400v1WiFi Router$40Broadcom BCM4718480 MHz MIPS 74Kc64 MB8 MB Flash

OpenWRT 18.06

Representative of consumer wireless routers, thisNetgear sports a Broadcom MIPS-based SoC, WiFiradios, a pair of Ethernet interfaces, and enoughRAM and flash to run a small Unix.

I took this router from the trash and installedan OpenWRT image. While new firmware canbe installed without opening the router, I addeda connection to the serial debug console, whichmost router manufacturers leave onboard.