[Jeff Tranter] has done a number of retrocomputing projects. But he wanted to tackle something more substantial. So he set out to build a 68000-based single board computer called the TS2 that he found in a textbook. He’s documented it in a series of blog posts (about 30 posts, by our count) and a video that you can see below.
The 68000 had a very rational architecture for its day. A flat memory space was refreshing compared to other similar processors, and the asynchronous bus made hardware design easier, too. While most CPUs of the era assumed bus devices could perform their service in a fixed amount of time, the 68000 used a handshake with devices to allow them to take the time they needed. Most other CPUs had to provide a mechanism for a slow device to stall the bus which was complicated and, in many cases, less efficient.
Researchers in the past have exfiltrated information through air gaps by blinking all sorts of lights from LEDs in keyboards to the main display itself. However, all of these methods all have one problem in common: they are extremely noticeable. If you worked in a high-security lab and your computer screen started to blink at a rapid pace, you might be a little concerned. But fret not, a group of researchers has found a new light to blink (PDF warning). Conveniently, this light blinks “randomly” even without the help of a virus: it’s the hard drive activity indication light.
All jokes aside, this is a massive improvement over previous methods in more ways than one. Since the hard drive light can be activated without kernel access, this exploit can be enacted without root access. Moreover, the group’s experiments show that “sensitive data can be successfully leaked from air-gapped computers via the HDD LED at a maximum bit rate of 4000 bit/s (bits per second), depending on the type of receiver and its distance from the transmitter.” Notably, this speed is “10 times faster than the existing optical covert channels for air-gapped computers.”
We weren’t born last night, and this is not the first time we’ve seen information transmission over air gaps. From cooling fans to practical uses, we’ve seen air gaps overcome. However, there are also plenty of “air gaps” that contain more copper than air, and require correspondingly less effort.
You might think that our community would always strive to be at the cutting edge of computing and use only the latest and fastest hardware, except for the steady stream of retrocomputing projects that appear. These minimalist platforms hark back to the first and second generation of accessible microcomputers, often with text displays if they have a display at all, and a simple keyboard interface to a language interpreter.
Often these machines strive to use the hardware of the day, and are covered with 74 logic chips and 8-bit processors in 40-pin dual-in-line packages, but there are projects that implement retrocomputers on more modern hardware. An example is [Sebastian]’s machine based upon a couple of PIC microcontrollers, one of which is an application processor with a PS/2 keyboard interface, and the other of which handles a VGA display interface. The application it runs calculates whether a 4-digit number is a prime and displays its results.
His write-up gives a fascinating overview of the challenges he found in creating a reliable VGA output from such limited hardware, and how he solved them. Though this one-sentence description makes a ton of work sound easy, horizontal sync pulses are generated as hardware PWM, and pixel data is streamed from the SPI bus. The VGA resolution is 640×480, upon which he could initially place a 10×10 block of text. Later optimizations extend it to 14×14.
Sometimes it’s not the power of the hardware but the challenge of making it perform the impossible that provides the attraction in a project, and on this front [Sebastian]’s retrocomputer certainly delivers. We’ve featured many other retrocomputers before here, some of which follow [Sebastian]’s example using modern silicon throughout, while others mix-and-match old and new.
The aptly named [Clickity Clack]’s new YouTube channel promises to be very interesting if he can actually pull off a working computer using nothing but relays. But even if he doesn’t get beyond the three videos in the playlist already, the channel is definitely worth checking out. We’ve never seen a simpler, clearer explanation of binary logic, and [Clickity Clack]’s relay version of the basic logic gates is a great introduction to the concepts.
Using custom PCBs hosting banks of DPDT relays, he progresses from the basic AND and XOR gates to half adders and full adders, explaining how carry in and carry out works. Everything is modular, so four of his 4-bit adder cards eventually get together to form a 16-bit adder, which we assume will be used to build out a very noisy yet entertaining ALU. We’re looking forward to that and relay implementations of the flip-flops and other elements he’ll need for a full computer.
We’ve seen a variety of home-made laptops using the Raspberry Pi and other single board computers over the years. Usually, they combine off-the-shelf USB keyboards and trackpads with HDMI monitor panels, and cases made from layered laser cut sheet, or 3D printed plastic.
[Surferboy]’s Raspberry Pi laptop is the latest effort to come before us, and its claim to fame is the use of the official Raspberry Pi 7″ touchscreen as a display. Full instructions and 3D printer files are available on Thingiverse so you can have a go at replicating it if a portable Pi is your thing.
He’s taken the bold step of not attempting to place all the Pi’s interfaces next to the outside of the case. Instead, he’s desoldered the Ethernet and USB ports. The USB connections were wired directly to the keyboard, display, and a couple of external ports on the right-hand side of his case. This leaves the finished laptop with no Ethernet. However, losing ethernet is a worthy tradeoff for the thinner package.
[Surferboy] also brought the GPIO header to a female socket on the rear of the unit. It’s unclear exactly what battery he uses except for a reference to the battery from his keyboard. Since a keyboard battery will be too small for Pi and display we are guessing a larger pack will be necessary.
Though the Ethernet port and battery issue would probably be a dealbreaker here this has the makings of a useful and compact laptop, it will be interesting to see if it is picked up and refined by the community.
A few months ago at the Hackaday | Belgrade conference, [Tsvetan Usunov], the brains behind Olimex, gave a talk on a project he’s been working on. He’s creating an Open Source Hacker’s Laptop. The impetus for this project came to [Tsvetan] after looking at how many laptops he’s thrown away over the years. Battery capacity degrades, keyboards have a fight with coffee, and manufacturers seem to purposely make laptops hard to repair.
The design of this laptop is completely Open Source. Usually when we hear this phrase, the Open Source part only means the electronics and firmware. Yes, there are exceptions, but the STL files for the PiTop, the ‘3D printable Raspberry Pi laptop’ are not available, rendering the ‘3D printable’ part of PiTop’s marketing splurge incongruent with reality. If you want to build a case for the Open Source laptop to date, [Bunnie]’s Novena, random GitHub repos are the best source. The Olimex TERES I is completely different; not only can you simply buy all the parts for the laptop, the hardware files are going up too. To be fair, this laptop is built with injection molded parts and will probably be extremely difficult to print on a standard desktop filament printer. The effort is there, though, and this laptop can truly be built from source.
As far as specs go, this should be a fairly capable laptop. The core PCB is built around an Allwinner ARM Cortex-A53, sporting 1GB of DDR3L RAM, 4GB of eMMC Flash, WiFi, Bluetooth, a camera, and an 11.6″ 1366×768 display. Compared to an off-the-shelf, bargain-basement consumer craptop, those aren’t great specs, but at least the price is consummate with performance: The TERES I will sell for only €225, or about $250 USD. That’s almost impulse buy territory, and we can’t wait to get our hands on one.
When I first got interested in computers, it was all but impossible for an individual to own a computer outright. Even a “small” machine cost a fortune not to mention requiring specialized power, cooling, and maintenance. Then there started to be some rumblings of home computers (like the Mark 8 we recently saw a replica of) and the Altair 8800 burst on the scene. By today’s standards, these are hardly computers. Even an 8-bit Arduino can outperform these old machines.
As much disparity as there is between an Altair 8800 and a modern personal computer, looking even further back is fascinating. The differences between the original computers from the 1940s and anything even remotely “modern” like an Altair or a PC are astounding. If you are interested in that kind of history, you should read a paper entitled “Electronic Computing Circuits of the ENIAC” by [Arthur W. Burks].
These mid-century designers used tubes and were blazing new ground. Part of what makes the ENIAC so different is that it had a different design principle than a modern computer. It was less a general purpose stored-program computer and more of a collection of logic circuits that could be configured to solve problems — sort of a giant vacuum tube FPGA, if you will. It used some internal representations that proved to be suboptimal which also makes it seem strange. The EDSAC — a later device — was closer to what we think of as a computer. Yet the ENIAC was a major step in the direction of a practical digital computer.
Cost and Size
The size of ENIAC is hard to imagine. The device had about 18,000 tubes, 7,000 diodes, 70,000 resistors, 10,000 capacitors, and 6,000 switches. There were 5 million hand-soldered joints! ([Thomas Haigh] tells us that while this is widely reported, the real number was about 500,000.) Physically, it stood 10 feet tall, 3 feet deep, and 100 feet long. The tube filaments alone required 80 kW of power. Even the cooling system consumed 20 kW. In total, it took 150 kW to run the beast.
The cost of the machine was about $487,000. Almost a half-million dollars in 1946 is plenty. But that’s nearly seven million dollars in today’s money. What was worth that kind of expenditure? The military built firing tables for shell trajectories. From the [Burks] paper:
“A skilled computer with a desk machine can compute a 60-second trajectory in about twenty hours…”
Keep in mind that in 1946, a computer was a person. [Burks] goes on to say that a differential analyzer can do the same job in 15 minutes. ENIAC, on the other hand, could do it in 30 seconds and with a greater precision than the differential analyzer.