As anyone who has been faced with a recently-manufactured household appliance that has broken will know, sometimes they can be surprisingly difficult to fix. In many cases it is not in the interests of manufacturers keen to sell more products to make a device that lasts significantly longer than its warranty period, to design it with dismantling or repairability in mind, or to make spare parts available to extend its life. As hardware hackers we do our best with home-made replacement components, hot glue, and cable ties, but all too often another appliance that should have plenty of life in it heads for the dump.
You’ve probably heard of the brave pilots, the so-called ‘few’, that took to the air in their Supermarine Spitfires and saved the day during the Battle of Britain. It’s a story that contains a lot of truth, but as is so often the case, it masks a story with a bit more complexity. Those pilots did scramble across the airfields of Southern England back in the summer of 1940, but more of them went into battle behind the controls of a Hawker Hurricane than its more glamorous stablemate.
The Hurricane might have been eclipsed by the Spitfire in the public’s eye, but not for [Marius Taciuc], who’s made a fully-functional RC model of one. Normally that wouldn’t be worthy of our attention, but in this case he’s employed a rather fascinating construction technique. He’s recreated the doped-fabric skin of the original by 3D-printing the frame of the aircraft and covering it in heat-shrink film, making this a very rare bird indeed.
The video below takes us through the steps including the development of the frame in a CAD package based on a tracing of a 2D aircraft picture, fitting the film, and finally attempts at flight that are unfortunately foiled by inappropriate wheel choice. But the short flight and crash does demonstrate that this construction method is durable, which leads on to our interest in it. While it evidently makes a functional aircraft, there are other applications that could benefit from such a lightweight and strong combination of materials.
One of the step changes in electronic construction at our level over the last ten or fifteen years has been the availability of cheap high-quality printed circuit boards. What used to cost hundreds of dollars is now essentially an impulse buy, allowing the most intricate of devices to be easily worked with. Many of us have put away our etching baths for good, often with a sigh of relief.
We’re pleased that [Riyas] hasn’t though, because they’ve etched an STM32 dev board that if we didn’t know otherwise we’d swear had been produced professionally. It sports a 176-pin variant of an STM32F4 on a single-sided board, seemingly without the annoying extra copper or lack-of-copper that we remember from home etching. We applaud the etching skill that went into it, and we’ll ignore the one or two boards that didn’t go entirely to plan. A coat of green solder mask and some tinning, and it looks for all the world as though it might have emerged from a commercial plant. All the board files are available to download along with firmware samples should you wish to try making one yourself, though we won’t blame you for ordering it from a board house instead.
It’s always nice to see that single board computers are not the sole preserve of manufacturers. If the RC2014 Micro doesn’t isn’t quite your style, there’s always the Blueberry Pi which features a considerably higher penguin quotient.
For many people, a retrocomputer is a classic machine from the past lovingly brought back to working order. But for some, the idea of a retrocomputer is wider than that, encompassing modern hardware that delivers to feel like a device from the past.
The Monotron from [Jonathan Pallant] is one such computer. It’s definitely a retrocomputer such as you might have found in the 1980s, but it’s running on a much more modern Tiva-C TI Launchpad dev board sporting an ARM Cortex M4.
The platform has been created entirely in Rust, and emulates what would have been a rather desirable machine in the early 1980s. With an 800×600 pixel 8-colour VGA display interface, 32k of RAM, and mono 8-bit audio, it already has a few simple demos and games running upon it. [Jonathan Pallant] has given more than one talk on its design and capabilities, we’ve placed one of them as a video below the break. There is even a PCB available which adds all the ports as well as a micro SD card slot for program storage.
We like the Monotron, and we look forward to seeing it develop. It’s an exciting time for retrocomputig with projects such as the RC2014 Z80 machine and the Gigatron TTL RISC processor, but is there space for an emulated one such as this? We hope so.
At the end of August I made the trip to Hebden Bridge to give a talk at OSHCamp 2019, a weekend of interesting stuff in the Yorkshire Dales. Instead of a badge, this event gives each attendee an electronic kit provided by a sponsor, and this year’s one was particularly interesting. The RC2014 Micro is the latest iteration of the RC2014 Z80-based retrocomputer, and it’s a single-board computer that strips the RC2014 down to a bare minimum. Time to spend an evening in the hackerspace assembling it, to take a look!
It’s An SBC, But Not As You Know It!
The kit arrives in a very compact heat-sealed anti-static packet, and upon opening was revealed to contain the PCB, a piece of foam carrying the integrated circuits, a few passives, and a very simple getting started and assembly guide. The simplicity of the design becomes obvious from the chip count, there’s the Z80 itself, a 6850 UART, 27C512 ROM, 62256 RAM, 74HCT04 for clock generation, and a 74HCT32 for address decoding. The quick-start is adequate, but there is also a set of more comprehensive online instructions (PDF) available.
Assembly of a through-hole kit is hardly challenging, though this one is about as densely-packed as it’s possible to make a through-hole kit with DIP integrated circuits. As with most through-hole projects, the order you pick is everything: resistors first, then capacitors, reset button and crystal, followed by integrated circuits.
I’m always a bit shy about soldering ICs directly to a circuit board so I supplemented my kit with sockets and jumpers. The jumpers are used to select an FTDI power source and ROM addresses for Grant Searle’s ROM BASIC distribution or Steve Cousins’ SCM 1.0 machine code monitor, and the kit instructions recommended hard-wiring them with cut-off resistor wires. There was no row of pins for the expansion bus because this kit was supplied without the backplane that’s a feature of the larger RC2014 kits, but it did have a set of right-angle pins for an FTDI serial cable.
Your Arduino Doesn’t Have A Development Environment On Board!
Having assembled my RC2014 Mini and given it a visual inspection it was time to power it up and see whether it worked. Installing the jumper for FTDI power, I attached my serial cable and plugged it into a USB port.
A really nice touch is that the Micro has the colours for the serial cable wires on the reverse side of the PCB, taking away the worry of getting it the wrong way round. A quick screen /dev/ttyUSB0 115200 to get a serial terminal from a bash prompt, hit the reset button, and I was rewarded with a BASIC interpreter. My RC2014 Micro worked first time, and I could straight away give it BASIC commands such as PRINT "Hello World!" and be rewarded with the expected output.
So I’ve built a little Z80 single board computer, and with considerably less work than that required for the fully modular version of the RC2014. Its creator Spencer tells me that the Micro was originally designed as a bargain-basement RC2014 as a multibuy for workshops and similar activities, being very similar to his RC2014 mini board but without provision for a Pi Zero terminal and a few other components. It lacks the extra hardware required for a more comprehensive operating system such as CP/M, so I’m left with about as minimal an 8-bit computer as it’s possible to build using parts available in 2019. My question then is this: What can I do with it?
So. What Can I Do With An 8-bit SBC?
My first computer was a Sinclair ZX81, how could it possibly compare this small kit that was a giveaway at a conference? Although the Sinclair included a black-and-white TV display interface, tape backup interface, and keyboard, the core computing power was not too far different in its abilities from this RC2014 Micro — after all, it’s the same processor chip. It was the platform that introduced a much younger me to computing, and straight away I devoured Sinclair BASIC and then went on to write machine code on it. It became a general-purpose calculation and computing scratchpad for repetitive homework due to the ease of BASIC programming, and with my Maplin 8255 I/O port card I was able to use it in the way a modern tech-aware kid might use an Arduino.
The RC2014 Micro is well placed to fill all of those functions as a BASIC and machine code learning platform on which to get down to the hardware in a way you simply can’t on most modern computers, and though the Arduino represents a far more sensible choice for hardware interfacing there is also an RC2014 backplane and I/O board available for the Micro’s expansion bus should you wish to have a go. Will I use it for these things? It’s certainly much more convenient than its full-sized sibling, so it’s quite likely I’ll be getting my hands dirty with a little bit of Z80 code. It’s astounding how much you can forget in 35 years!
The RC2014 Micro can be bought from Spencer’s Tindie store, with substantial bulk discounts for those workshop customers. If you want the full retrocomputer experience it’s a good choice as it provides about as simple a way into Z80 hardware and software as possible. The cost of simplicity comes in having no non-volatile storage and in lacking the hardware to run CP/M, but it has to be borne in mind that it’s the bottom of the RC2014 range. For comparison you can read our review of the original RC2014, over which we’d say the chief advantage of the Micro is its relative ease of construction.
A smartphone in 2019 is an essential piece of everyday equipment. Many of you are probably reading this page on one, and it will pack a very significant quantity of computing power into your hand. Pocket computing has a long history stretching back decades before the mass adoption of smartphones though, and Paleotronic has an interesting retrospective of that earlier history.
The piece starts with the Radio Shack PC-1, a rebadged Sharp with a calculator-style keyboard and a one-line alphanumeric LCD display, then continues through the legendary TRS-80 Model 100 to the era of the palmtop. It’s a difficult subject to cover in its entirety as there are so many milestones on the pocket computing path, but it’s an interesting read nevertheless as it successfully evokes the era when a 300 Baud connection via an acoustic coupler was a big deal. We might for example have mentioned the Atari Portfolio if only for its use by a young John Connor to scam an ATM in Terminator 2, and as any grizzled old sysadmin will tell you, there was a time when owning a Nokia Communicator might just save your bacon.
Of the classic pocket computing devices mentioned, only one has received significant coverage here. The TRS-80 model 100 still has a huge following, and among quite a few hacks featuring it we’ve seen one brought into the smartphone age by getting the ability to make a cellular connection.
TRS-80 Model 100 image: Jeff Keyzer from Austin, TX, USA [CC BY-SA 2.0]
If that’s your wish, then help could be at hand in the form of [Victor Ribeiro]’s RPiAPI. As its name suggests, it’s an API for your Raspberry Pi, and in particular it provides a simple web-accessible endpoint wrapper for the Pi’s GPIO library from which its expansion port pins can be accessed. By crafting a simple path on the address of the Pi’s web server each pin can be read or written to, which while it’s neither the fastest or most accomplished hardware interface for the platform, could make it one of the easiest to access.
Security comes courtesy of Apache password protected directories via .htaccess files, so users would be well-advised to consider the implications of connecting this to a public IP address very carefully. But for non experts in security it still has the potential to make a very useful tool in the armoury of ways to control hardware from the little single board computer. It’s not the first try at this idea as we’ve seen a PHP example early in the Pi’s lifetime as well as one relying upon MySQL, but it does seem to be a simpler option than the others.