Ingenuity’s 62nd Flight And Attempting A New Speed Record

October 12, 2023 by Maya Posch 17 Comments

One of the fun aspects of exploring a new planet is that you can set a lot of new records, as is the case with the very first Mars-based helicopter, Ingenuity. Since its inaugural flight on April 19th of 2021, Ingenuity has flown 61 times, setting various records for distance traveled and other parameters. Although setting the first record is easy on account of anything being better than literally nothing, the real challenge lies in exceeding previously set records, as the team behind Ingenuity seeks to do again with flight 62 and a new speed record.

Targeting October 12th, the goal is to travel 268 meters (1.33 furlong) at a maximum altitude of 18 meters while hitting 10 meters per second (36 km/h), which would shatter the 8 m/s (28.8 km/h) set by flight 60. Although still quite a distance to the 240 m/s required to hit Mach 1 on Mars, the fact that this feat is being performed by a first-of-its-kind helicopter in the thin Martian atmosphere, using off-the-shelf components that were expected to last maybe a handful of flights, is nothing short of amazing.

(Thanks to [Mark Stevens] for the tip!)

(Top image: Fourth flight of Ingenuity (circled), captured by Perseverance rover. Source: NASA/JPL)

A monitoring station as set up in the CEZ, featuring both the legacy (ARMS) and new wireless monitoring system.

How The 2022 CEZ Event Shows The Fragility Of Environmental Sensors In High-Risk Areas

October 10, 2023 by Maya Posch 3 Comments

In what reads somewhat like a convoluted detective story, the events unfolding at the Chornobyl Exclusion Zone (CEZ) in Ukraine during late February had the media channels lighting up with chatter about ‘elevated gamma radiation levels’, which showed up on the public CEZ radiation monitoring dashboard for a handful of gamma radiation sensors. This happened right before this reporting system went off-line, leaving outside observers guessing at what was going on. By the time occupying forces had been driven out of the CEZ, the gamma radiation levels were reported as being similar to before the invasion, yet the computer hardware which was part of the monitoring system had vanished along with the occupying forces. After considering many explanations, this left security researchers like [Ruben Santamarta] to consider that the high values had been spoofed.

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Learning About Ferroresonant Transformers While Fixing A 1970s Power Supply

October 9, 2023 by Maya Posch 22 Comments

Ferroresonant (constant voltage) transformer diagram. Secondary side is kept in full saturation with the tank, keeping voltage constant. (Credit: Usagi Electric)

While troubleshooting the power supply of a 1970s Centurion system, [Usagi Electrics] came across a fascinating feature of these units: the ferroresonant, or constant voltage transformer (CVT). The main difference between a regular transformer and a CVT is that the former has a quite direct correlation between the input and output voltage, as the magnetic flux induced on the primary side is directly translated to the secondary (output) side.

A CVT adds a second element on the secondary side in the form of a tank circuit (LC circuit) – essentially a large capacitor – along with a magnetic shunt that ‘short circuits’ part of the magnetic flux between the primary and secondary side. The result of this is that even as the primary side is kept well below the saturation point where efficiency plummets, the secondary side is kept within this saturation region, enabling a very constant output voltage across a wide range of input voltages. For the Centurion’s power supply this input range goes from 90 to 130 VAC.

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Pushing The Boundaries Of Tiny Mechanical Devices With Compliant Mechanisms

October 8, 2023 by Maya Posch 12 Comments

Mechanical actions underlie much of what makes modern day society function, whether it’s electric motors, combustion engines, switches, levers, or the springs inside a toy blaster gun that propel foam darts at unsuspecting siblings. Yet as useful as it would be to scale such mechanisms down to microscopic levels, this comes with previously minor issues on a macroscopic scale, such as friction and mechanical strength, becoming quickly insurmountable. Or to put in more simple terms, how to make a functioning toy blaster gun small enough to be handled by ants? This is the topic which [Mark Rober] explores in a recent video.

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Designing A Macintosh-to-VGA Adapter With An LM1881

October 7, 2023 by Maya Posch 3 Comments

Old-school Macintosh-to-VGA adapter. Just solve for X, set the right DIP switches and you’re golden.

If you’re the happy owner of a vintage Apple system like a 1989 Macintosh IIci you may know the pain of keeping working monitors around. Unless it’s a genuine Apple-approved CRT with the proprietary DA-15-based video connector, you are going to need at least an adapter studded with DIP switches to connect it to other monitors. Yet as [Steve] recently found out, the Macintosh’s rather selective use of video synchronization signals causes quite a headache when you try to hook up a range of VGA-equipped LCD monitors. A possible solution? Extracting the sync signal using a Texas Instruments LM1881 video sync separator chip.

Much of this trouble comes from the way that these old Apple systems output the analog video signal, which goes far beyond the physical differences of the DA-15 versus the standard DE-15 D-subminiature connectors. Whereas the VGA standard defines the RGB signals along with a VSYNC and HSYNC signal, the Apple version can generate HSYNC, VSYC, but also CSYNC (composite sync). Which sync signal is generated depends on what value the system reads on the three sense pins on the DA-15 connector, as a kind of crude monitor ID.

Theoretically this should be easy to adapt to, you might think, but the curveball Apple throws here is that for the monitor ID that outputs both VSYNC and HSYNC you are limited to a fixed resolution of 640 x 870, which is not the desired 640 x 480. The obvious solution is then to target the one monitor configuration with this output resolution, and extract the CSYNC (and sync-on-green) signal which it outputs, so that it can be fudged into a more VGA-like sync signal. Incidentally, it seems that [Steve]’s older Dell 2001FP LCD monitor does support sync-on-green and CSYNC, whereas newer LCD monitors no longer list this as a feature, which is why now more than a passive adapter is needed.

Although still a work-in-progress, so far [Steve] has managed to get an image on a number of these newer LCDs by using the LM1881 to extract CSYNC and obtain a VSYNC signal this way, while using the CSYNC as a sloppy HSYNC alternative. Other ICs also can generate an HSYNC signal from CSYNC, but those cost a bit more than the ~USD$3 LM1881.

Implementing Commodore’s IEC Bus Protocol On A KIM-1 Single Board Computer

October 7, 2023 by Maya Posch 4 Comments

Although the PET is most likely the more well-known of Commodore’s early computer systems, the KIM-1 (Keyboard Input Monitor) single board computer was launched a year prior, in 1976. It featured not only the same MOS 6502 MPU as later Commodore systems, but also an MCS6530 PIO IC that contained the ROM, RAM and programmable I/O, reminiscent of later I/O chips on Commodore systems. As the KIM-1 was only designed to be used with an external tape drive (and a terminal for fancy users), adding a floppy drive like the ubiquitous 1541 with its IEC bus interface was not a first-party accessory. How the IEC bus can be retrofitted to a KIM-1 system is demonstrated in this video by the Commodore History channel.

The Commodore KIM-1 hardware is almost directly compatible with the C64 hardware. (Credit: Commodore History on YouTube)

What is most notable is just how similar the KIM-1 hardware is to later PET and VIC hardware, with the CIA and PIO ICs featuring the same requisite pins for this purpose, and requiring only the addition of an inverting (SN7406) IC and an EPROM featuring the new code to support the proprietary Commodore IEC bus protocol, which was mostly pilfered byte-for-byte from a C64 kernal ROM.

With some creative breadboarding in place and using nothing more than the on-board LED display and keyboard matrix, it was then possible to write to the inserted floppy disk, and also to read back from it. What’s interesting here is that this essentially replaces the tape drive as target for the KIM-1, which thus retains a lot of the original functionality, but with a big performance boost. While perhaps only interesting as an academic exercise, it’s definitely an interesting look at the early beginnings of what would blossom into the Commodore 64.

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Zilog’s Forgotten Operating System: Z80-RIO

October 6, 2023 by Maya Posch 32 Comments

When it comes to famous operating systems for the Z80 and similar Zilog processors, the first and maybe only one to come to mind is CP/M, which was even made its presence known on the dual-CPU (8502 and Z80) Commodore 128. Yet Zilog also developed its own operating system, in the form of the comprehensively titled Z80 Operating System with Relocatable Modules and I/O Management (Z80-RIO for short). With limited documentation having survived, [Ralf-Peter Nerlich] has set out to retain and recover what information he can on RIO and the associated Programming Language Zilog (PLZ) after working with these systems himself when they were new.

A Zilog MCZ 1/20 system from around 1979. (Credit: Herb Johnson)

Perhaps unsurprisingly, neither Z80-RIO nor PLZ were targeting the regular consumer market when they were brought to market in the late 1970s, but were part of Zilog’s focus on industrial markets, as well as laboratories and elsewhere that could benefit from a versatile, programmable computer system for control and automation.

As part of an integrated hardware/software solution, Zilog released a series of computer systems, such as the MCZ 1/20 of which a number of examples survive today. Herb Johnson’s collection and restoration projects provide a good overview of not only the base systems, but also the expansion cards available for these systems. Right along with the Z80-RIO OS providing the ability to customize the system for the target usage, the underlying hardware could also be configured with just the expansion boards required, or conceivably even custom boards.

Of course, it doesn’t take many guesses to figure out what happened to Z80’s RIO OS and related, with the 1980s heralding massive shifts in the computer markets. Although now functionally obsolete for decades, it’s good to see such preservation efforts of 1970s computing systems and related software. These are after all the foundations on which modern day computing is built.

(Thanks to [Stephen Walters] for the tip)