What Next For The SBC That Has Everything?

In the decade-and-a-bit since the first Raspberry Pi was launched we’ve seen an explosion of affordable single-board computers (SBCs), but as the prices creep up alongside user expectation and bloat, [Christopher Barnatt] asks where the industry will go next.

The Pi started with an unbeatable offer, $35 got you something similar to the desktop PC you’d had a decade earlier — able to run a Linux desktop on your TV from an SD card. Over the years the boards have become faster and more numerous, but the prices for ARM boards are now only nominally as affordable as they were in 2012, and meanwhile the lower end of x86 computing is now firmly in the same space. He demonstrates how much slower the 2023 Raspberry Pi OS distribution is on an original Pi compared to one of the early pre-Raspbian distros, and identifies in that a gap forming between users. From that he sees those people wanting a desktop heading towards the x86 machines, and the bare-metal makers at the lower end heading for the more powerful microcontrollers which simply weren’t so available a decade ago.

We have to admit that we agree with him, as the days when a new Raspberry Pi board was a special step forward rather than just another fast SBC are now probably behind us. In that we think the Pi people are probably also looking beyond their flagship product, as the hugely successful lunches of the RP2040 and the industrial-focused Compute Module 4 have shown.

What do you think about the SBC market? Tell us in the comments.

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Hackerboards: Making Finding The Right Single-Board Computer Easy

The great thing about the wide availability of single-board computers (SBCs) is that it offers such a large selection of options, in terms of CPU performance, GPU features, RAM size, I/O options and much more. This is however also the largest issue, especially with the annual surge of new boards with new feature sets. Trying to make sense of all these offerings is the recently overhauled Board-DB, also known as Hackerboards.

As [Martijn Braam] explains in the blog post on the changes, a major upgrade over the old Hackerboards (which we covered in 2016) is a far more extensive set of parameters that can be filtered against. This makes a fine-grained selection of detailed features significantly easier, which is also reflected in the technical specifications comparison feature. With over 450 active entries there are a lot of boards that can already be filtered on, but manufacturers are invited to take up contact to add further entries, which should keep the list up to date.

Incidentally, if you’d like to know how [Martijn] gets those gorgeous PCB photographs, he wrote a whole a separate write-up that goes over his camera setup.

Thanks to [Vlad] for the tip.

A breadboard with a few DIP chips

Minimalist 6502 System Uses A CPU And Not Much Else

A central processing unit, or CPU, is the heart of any computer system. But it’s definitely not the only part: you also need RAM, ROM and at least some peripherals to turn it into a complete system that can actually do something useful. Modern microcontrollers typically have some or all of these functions integrated into a single chip, but classic CPUs don’t: they were meant to be placed on motherboards along with dozens of other chips. That’s why [c0pperdragon]’s latest project, the SingleBreadboardComputer, is such an amazing design: assisting its 6502 CPU are just four companion chips.

The entire system takes up just one strip of solderless breadboard. Next to the CPU we find 32 KB of SRAM, 32 KB of flash and a clock oscillator. The fifth chip is a 74HC00 quad two-input NAND gate, which is used as a very tiny piece of glue logic to connect everything together. Two of its NAND gates are used for address decoding logic, allowing either the ROM or RAM chip to be selected depending on the state of the CPU’s A15 line as well as blocking the RAM during the low phase of the system clock. The latter function is needed because the address lines are not guaranteed to be stable during the low phase and could cause writes to random memory locations.

The remaining two NAND gates are connected as an RS-flipflop in order to implement a serial output. This is needed because the CPU cannot keep its outputs in the same state for multiple clock cycles, which is required for a serial port. Instead, [c0pperdragon] uses the MLB pin, normally used to implement multiprocessor systems, to generate two-clock pulses, and stores the state in the flipflop for as long as needed. A few well-timed software routines can then be used to transmit and receive serial data without any further hardware.

Currently, the only software for this system is a simple demonstration that sends back data received on its serial port, but if you fancy a challenge you could write programs to do pretty much anything. You could probably find some inspiration in other minimalist 6502 boards, or projects that emulate a complete motherboard in an FPGA.

The State Of The SBC Interface Ecosystem, Is It Time To Design A Standard?

We are spoiled for choice when it comes to single board computers, whether they be based around a microcontroller or a more capable SoC capable of running an operating system such as GNU/Linux. They can be had from well-established brands such as Arduino, Adafruit, or Raspberry Pi, or from a Wild West of cheaper Far Eastern modules carrying a plethora of different architectures.

Everyone has their own favourite among them, and along with that comes an ecosystem of operating systems and software development environments. There’s another aspect to these boards which has evolved; certain among them have become de facto interface connector standards for hardware peripherals. Do these standards make any sense? Let’s talk about that.

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Front and back of a handheld 6502 computer with bubble LED displays

The Pocket265 Is A Pocket-Sized 6502 Single-Board Computer

Single-board computers have been around ever since microprocessors became affordable in the 1970s and never went away. Today we have Raspberry Pis and LattePandas, while back in the ’70s and ’80s there were the Ferguson Big Board, the KIM-1 and a whole array of Intel SDK boards. Although functionally similar to their modern counterparts with a CPU, RAM, ROM and some basic peripherals, the old boards were huge compared to today’s tiny platforms and typically required a rather beefy power supply to operate.

It doesn’t have to be that way though, as [Aleksander] shows with the Pocket265: a handheld 6502 single-board computer somewhat reminiscent of the famous KIM-1. Like that classic machine, it’s got a hexadecimal keypad to enter programs using machine code and a row of LED displays to show the programs’ output. Unlike the KIM, the Pocket265 is small enough to hold in one hand and uses bubble LED displays, which make it look more like a programmable calculator from the 1970s. It comes with a lithium battery that makes it truly portable, as well as a sleek 3D printed case to make it more comfortable to hold than a bare circuit board.

The single ROM chip contains a monitor program that runs the basic user interface. It also makes programming a bit less tedious by implementing a number of system calls to handle things like user input and display output. A serial EEPROM enables local data storage, while a UART with a USB interface enables data transfer to other computers. If you’re interested in building and programming such a machine yourself, [Aleksander] helpfully provides code examples as well as full hardware documentation on his GitHub page.

The 6502 remains a firm favorite among hardware hackers: some projects we recently featured with this CPU include one beautifully made machine, this easy-to-build single-board computer and this huge breadboard-based contraption. Looking for something smaller? Try this tidy little board or this 6502 coupled to an FPGA.

A purple PCB with many DIP chips including a 6502

Hackaday Prize 2022: Reuse Those DIP Chips To Make A 1980s-Style Single-Board Computer

With the Great Chip Shortage still delaying deliveries of new components, now might be a good time to look around your lab and inspect those piles of chips that you thought “might come in handy one day”. Chances are you’ll find a good stack of 74xx series logic, once ubiquitous but today mostly obsolete thanks to powerful microcontrollers and FPGAs. It would be a shame to let them go to waste, so why not use them to make a neat 1980s-style computer?

With this idea in mind, [Anders Nielsen] designed the ABN6502: a single-board computer based on the venerable 6502 processor, but with relatively modern interfaces like a VGA monitor output, a PS/2 keyboard connector and even a wireless module to simplify firmware uploads from a PC. One design requirement was to minimize the number of new components needed; the average hacker interested in building the ABN6502 will probably have many of the chips lying around somewhere in their workshop.

The component list reads like a typical bill of materials for a 6502-based computer, but comes with a lot of flexibility to allow for part subsititution. For the CPU, both the classic NMOS 6502 as well as the modern CMOS-based 65C02 are supported, along with their 6522 companion chip that provides I/O ports and timers. A ROM socket can hold either modern, fast flash chips or traditional but slow UV-erasable EPROMs.

Instead of using DRAM chips with their complicated refresh requirements, [Anders] went for 32 KB of SRAM to implement the main memory; unaffordable in the ’80s but easily available today. Standard 74xx series logic chips glue all the components together, again with several options to add or remove features as the user prefers. Pin headers bring out the I/O ports for easy connection to external peripherals.

The ABN6502’s software library is currently limited to a bootloader, but a complete development toolchain based on the CC65 compiler should make it easy to develop all kinds of programs on this platform. We’ve already featured the clever wireless ROM flashing system, as well as a demonstration of the 6502 driving RGB LEDs.

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An M-Core module plugged into its devboard. Around it are Ethernet, HDMI, Type-C, two USB-A ports, one MicroSD card socket and one unpopulated footprint for a WiFi module

MangoPi To Bring A SD-Card-Sized Linux Module

Today’s Diminutive Device is a small castellated System-On-Module (Twitter link, nitter proxy) from [MangoPi] called M-Core, with a quad-core A53 CPU and 1 GB of RAM. As such, it’s very capable of running Linux, and even sports an HDMI output! Taking a closer look at the devboard picture, we can spot traces for three USB 2.0 ports, what seems to be two SDIO interfaces for MicroSD or WiFi cards, and an Ethernet MagJack with its termination network. This is a decent set of interfaces, rivaling what we’d expect out of a Pi Zero!

More importantly, this module is as small as an SD card itself – or as an OLED display that we hobbyists sprinkle onto our projects. Having power of Linux in such a small footprint is certainly something to behold! The back of the module is mostly flat, save for a few decoupling capacitors on the other side of the CPU – it seems, an Allwinner H616. On top of it, we can see the CPU itself, a small buck regulator and a DDR3 RAM chip, as well as tightly-packed passives. There’s even an unpopulated footprint for a DFN8 QSPI flash chip – with a lightweight enough OS build, you could perhaps dedicate your MicroSD card to storage only.

The devboard for uses the “FlexyPins”-like connectivity technique we’ve covered recently, and [MangoPi] say they bought those pins on TaoBao. We can’t help but be a bit amused at the thought of putting HDMI through such connections, but it seems to work well enough! Castellated modules like these are relatively easy to work with, so it shouldn’t be hard to literally pop this module out of the devboard and figuratively pop it onto your PCB. Next step is, reportedly, porting Armbian to this board, likely solving quite a few software support hurdles.

MangoPi have been posting updates on their Twitter page over the last few weeks, and, as it comes with the format, a lot of questions are left unanswered. Why does the devboard only show a single linear regulator of the kind we typically expect to deliver 1 A at most? Will we get higher-RAM versions? What’s the price going to look like? Will this module ever get to market? We can only hope, but if it does indeed, we are sure to see a few projects with these, whether it’s smart glasses, smart displays, phones, handhelds or malicious wall chargers. As usual, community makes or breaks an SBC, and we shall watch this one closely.

We thank [WifiCable] and [DjBiohazard] for sharing this with us!