Review: Single Board 65C02 and 65C816 Computers

The 6502 is a classic piece of computing history. Versions of this CPU were found in everything from the Apple ][, to the Nintendo Entertainment System, and the Commodore 64. The history of the 6502 doesn’t end with video games; for the last forty years, this CPU has found its way into industrial equipment, medical devices, and everything else that doesn’t need to be redesigned every two years. Combine the longevity of the 6502 with the fact an entire generation of developers first cut their teeth on 6502 assembly, and you have the makings of a classic microprocessor that will, I’m sure, still be relevant in another forty years.

The cathedral of The 6502 is Western Design Center. For more than 35 years, WDC has been the home of 6502-related designs. Recently, WDC has been interested in the educational aspects of the 6502, with one of the VPs, [David Cramer], lending his time to an after-school club teaching opcodes.

The folks at WDC recently contacted me to see if I would give their hardware a close look, and after providing a few boards, this hardware proved to be both excellent. They’re great for educators adventurous enough to deviate from the Arduino, Processing, and Fritzing zeitgeist, and for anyone who wants to dip their toes into the world of 65xx development.

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Olimex Claims the World’s First $9 Computer Costs $39

The C.H.I.P. from Next Thing Co. bills itself as the world’s first nine dollar computer. That’s not a lie; their Kickstarter took in over two million dollars for a tiny single board computer with composite Video, WiFi, Bluetooth 512MB of RAM, 4GB of storage, and a 1GHz CPU. That’s a complete computer, sans keyboard, mouse, and monitor. You won’t get that with the $35 Raspberry Pi – you’ll need to add a WiFi adapter and an SD card for the same functionality – and you won’t get that with any other single board computer.

Understandably, the C.H.I.P. is already extremely successful. The company behind it has about 50,000 pre-orders, and people lined up to wait until well into next year for this computer. Exactly how Next Thing Co. managed to build a single board computer and send it out the door for nine dollars is a question that has yet to be answered, and is leaving more than a few people puzzled.

The Olimex blog has given their opinion of the C.H.I.P, and if that’s to be believed, the news isn’t good. The guys at Olimex know their stuff when it comes to making cheap single board computers; they have more than a few for sale, and they know what the Flash and DRAM market is like. To them, it’s impossible to sell a computer like the C.H.I.P. at $9. A quote from Allwinner for a similar module is $16 at the quantity Next Thing Co. would be looking at. That’s just the module with RAM and Flash – no Wifi, no board, no connectors. How could it be possible to sell this computer for only $9?

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C.H.I.P. is a Linux Trojan Horse for Nine Bucks

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.

chip-single-board-computer

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.

An Amazing DIY Single Board ARM Computer with BGA

DIY Single Board Computer ARM

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!

DUO Decimal – a Minimalist Single Board Computer

duodecimal

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.

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The Three Chip Retrocomputer

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.

Easy to build Z80 single board computer

[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.

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