I’m sure you’ve already heard about C.H.I.P, the $9 Linux computer. It is certainly sexy to say nine-bucks but there should really be an asterisk next to that number. If you want things like VGA or HDMI you need an adapter board which adds cost (natively the board only supports composite video output). I also have questions about MSRP once the Kickstarter is fulfilled. But what’s on my mind isn’t cost; this is still going to be in the realm of extremely-inexpensive no matter what shakes out. Instead, I’d like to look at this being the delivery device for wider Linux acceptance.
The gist of the hardware is a small board with a SoC boasting a 1GHz clock, half a gig of ram, four gigs of flash, one USB, WiFi and Bluetooth. It also has add-ons that make it a handheld and is being promoted as a gaming console. It’s amazing what you get out of these SoC’s for the cost these days, isn’t it?
For at least a decade people have claimed that this is the year of the Linux desktop. That’s not the right way to think. Adults are brand-loyal and business will stick to things that just work. Trying to convert those two examples is a sisyphean effort. But C.H.I.P. is picking up on a movement that started with Raspberry Pi.
These are entry-level computers and a large portion of the user-base will be kids. I haven’t had a hands-on with this new board, but the marketing certainly makes an effort to show how familiar the GUI will be. This is selling Linux and popular packages like LibreOffice without even tell people they’ll be adopting Linux. If the youngest Raspberry Pi users are maturing into their adolescence with C.H.I.P, what will their early adult years look like? At the least, they will not have an ingrained disposition against Open Source Software (unless experiences with Rasbperry Pi, C.H.I.P., and others is negative). At best they’ll fully embrace FOSS, becoming the next generation of code contributors and concept evangelists. Then every year will be the year of the Linux desktop.
Typically, you buy a single board Linux computer. [Henrik] had a better idea, build his own ARM based single board computer! How did he do it? By not being scared of ball grid array (BGA) ARM processors.
Everyone loves the Raspberry Pi and Beagle Board, but what is the fun in buying something that you can build? We have a hunch that most of our readers stay clear of BGA chips, and for good reason. Arguably, one of the most important aspects of [Henrik’s] post is that you can easily solder BGAs with cheaply available tools. OSH Park provides the inexpensive high-quality PCBs, OSH Stencils provides the inexpensive stencils, and any toaster oven allows you to solder even the most difficult of components. Not only does he go over the PCB build, he also discusses the bootloader, u-boot, and how to get Linux running.
Everything worked out very well for [Henrik]. It’s a good thing too, cause we sure wouldn’t want to debug a PCB as complicated as this one. What projects have you built that use a BGA? Let us know how it went!
If you’ve ever struggled to fit your program into the RAM and ROM of a small micro, you’ll appreciate [Jack’s] creation, the DUO Decimal. DUO Decimal is a small single board computer running on an Atmel ATtiny84. The ’84 has 8KB flash memory, 512 bytes of SRAM, and 512 bytes of EEPROM. Not as bad as a the old days, but still tight by today’s standards.
User input to the DUO Decimal is through two buttons. Output is via a 7 segment numeric LED display. Not the easiest for typing in long programs, but on par with the switches and blinkenlights of the past. 3 bits of GPIO are available for connections to your own circuits.
[Jack] didn’t just design a board, he designed an entire language. DUO Decimal is programmed in an interpreted language called DUO Decimal Numeric Code (DDNC). There are 47 DDNC commands, covering everything from basic math to list manipulation. Programs can be entered through the buttons, or save your fingertips by downloading them through the AVR isp interface. The entire C code for the DUO Decimal, including the DDNC interpreter is available on [Jack’s] website.
[Jack] created several example DDNC programs, including a 6 function calculator with trigonometry, a Mandelbrot set tester, and an implementation of the rock paper scissors game. There’s even a platformer action game, though graphics on a single 7 segment display are simplistic to say the least.
Continue reading “DUO Decimal – a Minimalist Single Board Computer”
Where homebrew computers are usually complex bundles of wires and chips, [Mike]’s own single board computer is not. It’s a three-chip computer with only a CPU, RAM, and a microcontroller that is able to emulate the retrocomputers of yore.
Normally, a homebrew computer project requires some amount of ‘glue’ logic – a few NAND, OR, or inverters to combine signals and send them where they’re needed for address decoding. This tiny pocket computer doesn’t need any of that; all the address decoding is done on a 40-pin PIC microcontroller.
With 64kB on the PIC 18F46K22, there’s enough space for all the address decoding logic, space for a pseudo ACIA mapped onto the $DF page, and a ROM image that provides a monitor program and a copy of BASIC. Basically, with the addition of a USB to serial adapter, this is a three chip 6502 single board computer, and with the right ROM monitor can emulate an Apple I, Woz monitor included.
Yes, 6502 projects are a dime a dozen, but [Mike]’s work with the address decoding logic on the microcontroller is top-notch. There are a few remaining chip select lines in his schematic, and with another microcontroller it would be easy to add VGA out, a compact flash adapter, or some other really cool peripherals. Good thing there’s an expansion port on this thing.
[Alexis] sent in a single board computer he’s been working on. The project goal of his build was making it easily reproducible. From looking at the schematics, it’s one of the simplest fully-functional computers we’ve seen. The build runs CP/M 2.2 off of two 3.5 inch floppies. This opens up a lot of options as to what software is already available. Although it operates over a serial terminal, [Alexis] pretty much duplicated an Osborne I, only at double the speed.
[Alexis] got a little e-fame from his earlier 8088 homebrew computer built from very early 8088’s rescued from an electronics junk shop. These 8088 computers made the blog rounds by playing Still Alive with a SID chip from a Commodore 64 and a YM2151 FM synth chip.
For now, I guess we’ll have to settle for a video of [Alexis]’ Z80 computer running CP/M. Check out a video after the break of his computer running the greatest Infocom adventure, Hitchhiker’s Guide to the Galaxy.
Continue reading “Easy to build Z80 single board computer”