Dumping 90’s Honda ECU Programming With Arduino

July 2, 2021 by Danie Conradie 19 Comments

[P1kachu] owns a pair of early 1990’s Honda’s with custom tuning on their stock ECUs, and after having to get the ECU repaired on his ’93 civic, he found himself going down the rabbit hole of Honda ECU EPROM chips.

During the repair process, the tuning shop owner, or [Tuner-san] as [P1ikachu] refers to him, made a backup of the custom tuning to another EPROM chip. This was done with an old Advantest R4945A EPROM programmer, which [Tuner-san] supposedly also used to clone Famicom cartridges back in the day. After realizing that [Tuner-san] could only clone the contents, but not view or modify it, he started looking at ways to do that.

EPROMS are programmed using higher voltage (12.5 V – 25 V) but to read them 5 V is used. The memory address is selected by setting each of the 15 address pins high or low, and then reading the status of the 8 data pins to extract one byte of data. Rinse and repeat for each of the 256 memory addresses on the Microchip 27C256 EPROM. One of the previous owners of [Pikachu]’s Civic made some unknown tuning changes, so he is in the process of looking at the dumped data to see what was changed. Once he has completed figuring out the programming table of the EPROM, he plans to do some testing with [Tuner-san] to possible smooth out the rev limited.

An interesting aspect of EPROMs is that they are erased using UV light, which sets all the memory bits to 1. During programming, selected bits can be set to 0, but it’s not possible to set them back to 1 without erasing the entire chip again.

Messing around with the computers in cars is not only for tuning, but can also expose some rather serious security flaws, especially in modern vehicles.

RF Burns And Exploding PC Speakers: Sophos Looks At The Evidence

June 21, 2021 by Jenny List 24 Comments

Every year in the month of June, someone by the unlikely name of [R.F. Burns] posts a question to the Linux Kernel Mailing List asking whether a Linux kernel module is possible that would blow the PC speaker. It’s fairly obviously a joke, which is why the UK-based anti-virus company Sophos have devoted a light-hearted blog post to it.

The post is an interesting diversion into early PC sounds, when the only hardware guaranteed to be present was a small speaker hooked up to a bit on an output port. The bit could be cycled for square wave beeps, or with a lot of clever manipulation could put out a low-bitrate PWM that delivered almost intelligible sounds including music and voice. They conclude that since the speaker would have been designed to be at the full amplitude of the 5-volt output bit all the time it should be impossible to blow it from software, and we’d be inclined to agree. There’s a remote possibility that some speakers might have a resonant frequency that could be found in software, but we’re not entirely convinced.

Your Hackaday scribe might have spent a while in a university computer lab back in the day trying and failing to write C code that would produce a usable PWM on an XT speaker, but those with long memories might recall the PC speaker driver for Windows 3.1. If you’re a fan of chiptune music there are even entire albums written for this most basic of instruments.

Header image: MKFI, Public domain.

Vacuum Tube Magic Comes To The 741

June 19, 2021 by Jenny List 41 Comments

Some of you may remember a recent project that featured on these pages, a 555 timer reproduced using vacuum tubes. Its creator [Usagi Electric] was left at loose ends while waiting for a fresh PCB revision of the 555 to be delivered, so set about creating a new vacuum tube model of a popular chip, this time the ubiquitous 741 op-amp. (Video, embedded below.)

The circuit is fairly straightforward, using six small pentodes. The first two are a long-tailed pair as might be expected, followed by two gain stages, then a final gain stage feeding a cathode follower with feedback. It’s neatly built on a PCB with IC-style “pins” made from more PCB material, then put in a huge replication of an IC socket on a wooden baseboard.

The result is an op-amp, but not necessarily a good one. He looks at the AC performance instead of the DC even though it’s a fully DC-coupled circuit, and finds that while it performs as expected in a classic op-amp circuit it still differs from the ideal at higher gain. The frequency response is poor too, something he rectifies by replacing the feedback capacitor with a smaller value. Sadly he doesn’t look at its common mode performance, though we’d expect that without close matching of the tubes it might leave something to be desired.

It’s obvious that this project would never be selected as an op-amp given the quality of even the cheapest silicon op-amp in comparison. But its value is in a novelty, a talking point, and maybe a chance to learn about op-amps. For that, we like it.

We covered the vacuum tube 555 when details of it emerged, but if op-amps are your bag we’ve looked at a simple one very closely indeed.

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2:3 Scale VT100 Terminal Gets Closer To Its Roots

June 15, 2021 by Tom Nardi 42 Comments

When [Michael Gardi] finished his scaled down DEC VT100 replica a few months ago, he made it very clear that the project was only meant to look like a vintage terminal on the outside. A peek into the case revealed nothing more exotic than a Raspberry Pi running its default operating system, making the terminal just as well suited to emulating classic games as it was dialing into a remote system. But as any hacker knows, some projects end up developing a life of their own.

It started simply enough. The addition of an RS-232 Serial HAT to the Raspberry Pi meant that the 3D printed VT100 could actually operate as a serial terminal using software such as minicom. Then [Lars Brinkhoff] got involved. He loved the look of the printed VT100, and thought it deserved better than a generic terminal emulator. So he went ahead and started developing a custom terminal simulator for it to run.

The idea here is that an an 8080 emulator actually runs an original VT100 firmware ROM, warts and all. It makes all the beeps and chirps you’d expect from the real hardware, and there’s even some OpenGL trickery used to mimic an old CRT display, complete with scan lines and a soft glow around characters.

Naturally the visual effects consume a fair amount of processing power, so [Lars] cautions that anything lower than the Pi 4 will likely experience slowdowns. Of course, nothing is stopping you from running the simulator on your desktop machine if you’re looking for that classic terminal experience.

Did this gorgeous recreation of the VT100 need to have a true serial interface or a simulator that recreates the unique menu system of the original? Not at all. Even without those additions, it blew us away when [Michael] first sent it in. But are we happy that these guys have put in the time to perfect this already stellar project? We think you already know the answer.

Restoring A Vintage Tube Tester To Its Former Glory

June 9, 2021 by Tom Nardi 38 Comments

It can be difficult for modern eyes to make much sense of electronics from the 1960s or earlier. Between the point-to-point soldering, oddball components, and the familiar looking passives blown up to comical proportions like rejected props from “Honey, I Shrunk the Kids”, even experienced hardware hackers may find themselves struggling to understand what a circuit is doing. But that didn’t stop [Cat0Charmer] from taking the time to lovingly restore this Hickok Cardmatic KS-15874-L2 tube tester.

The good news was that the machine had nearly all of its original parts, down to the Hickok branded tubes in the power supply. Unfortunately it looks like a few heavy handed repairs were attempted over the years, with a nest of new wires and components intermixed with what [Cat0Charmer] actually wanted to keep. The before and after shots of individual sections of the machine are particularly enlightening, though again, don’t feel to bad if you still can’t make heads or tails of the cleaned up version.

Hiding new capacitors inside of the old ones.

As you’d expect for a machine of this age, many of the original components were way out of spec. Naturally the capacitors were shot, but even the carbon composition resistors were worthless after all these years; with some measuring 60% away from their original tolerances.

We particularly liked how [Cat0Charmer] hollowed out the old capacitors and installed the new modern ones inside of them, preserving the tester’s vintage look. This trick wasn’t always feasible, but where it was applied, it definitely looks better than seeing a modern capacitor adrift in a sea of 60’s hardware.

After undoing ham-fisted repairs, replacing the dud components, and installing some new old stock tubes, the tester sprung to life with renewed vigor. The previously inoperable internal neon lamps, used by the tester’s voltage regulation system, shone brightly thanks to all the ancillary repairs and changes that went on around them. With a DIY calibration cell built from the schematics in an old Navy manual, [Cat0Charmer] got the tester dialed in and ready for the next phase of its long and storied career.

We love seeing old hardware get restored. It not only keeps useful equipment out of the scrap heap, but because blending new and old technology invariably leads to the kind of innovative problem solving this community is built on.

The Epic Saga Of Hacking Knights Of The Round

June 8, 2021 by Tom Nardi 3 Comments

For the uninitiated, Knights of the Round was a hack-and-slash arcade game released by Capcom in 1991 that rather loosely followed the legend of King Arthur and the eponymous Knights of the Round Table. In it, up to three players make their way from stage to stage, vanquishing foes and leveling up their specific character’s weapons and abilities. But [Sebastian Mihai] was looking for a new way to experience this classic title, so he decided to reverse engineer the game and create his own version called Warlock’s Tower.

Those familiar with the original game will no doubt notice some of the differences right away while watching the video below, but for those who don’t have an intimate knowledge of Arthur’s digital adventures, the major changes are listed on the project’s web page. Among the most notable are the removal of cooperative multiplayer and stage time limits. This turns the game from a frantic beat ’em up to a more methodical adventure. Especially since you now have to compete the game in a single life. If we had to guess, we’d say [Sebastian] prefers his games to have a bit of a challenge to them.

Even if you aren’t interested in playing Warlock’s Tower yourself, the story of how [Sebastian] created it is absolutely fascinating. He started with zero knowledge of Motorola 68000 assembly, but by the end of the project, was wrangling multiple debuggers and writing custom tools to help implement the approximately 70 patches that make up the custom build.

The hundreds of hours of work that went into creating these patches is documented as a sort of stream of consciousness on the project page, allowing you to follow along in chronological order. Whether it inspires you to tackle your own reverse engineering project or makes you doubt whether or not you’ve got the patience to see it through, it’s definitely worth a read. If you’re a Knights of the Round fan, you should also take a look at the incredible wealth of information he’s amassed about the original game itself, which honestly serves as an equally impressive project in its own right.

Modified versions of classic games, known colloquially as “ROM hacks” are fairly common among serious fans who want to see their favorite games improved over time. While they aren’t always as ambitious as Warlock’s Tower, they all serve as examples of how a dedicated community can push a product well beyond the scope envisioned by its original creators.

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An ALU As A Desktop Calculator Has Stunning Style From Days Gone By

June 7, 2021 by Jenny List 9 Comments

Those of you with an interest in microcomputer history will know that there is a strong crossover between the path of electronic calculator evolution and the genesis of the integrated CPU. Intel’s 4000 was famously designed for a calculator, and for a while in the 1970s these mathematical helpers were seen as the wonder of the age. [Simon Boak]’s calculator is a curious throwback to that era, as it’s not a decimal calculator as we’d know it but a hexadecimal device that simply computes using the functions of the famous 74181 ALU chip.

An ALU, or to give it its full name an Arithmetic Logic Unit, is a component of a CPU with two inputs and one output that can perform any of a range of binary functions upon the two inputs and return the result on the output. This calculator has two of them for eight bits of raw adding power, with a hexadecimal keypad for setting the inputs and a set of 7-segment displays for showing the results. It’s housed in an achingly retro folded sheet metal console case with wooden end pieces that would have graced any engineer’s desk with pride back in about 1975. We may not need one, but we really want one!