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VCF East 2021: Novasaur TTL Computer Sets the Bar

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There was certainly no shortage of unique computers on display at the 2021 Vintage Computer Festival East; that’s sort of the point. But even with the InfoAge Science and History Museum packed to the rafters with weird and wonderful computing devices stretching back to the very beginning of the digital age, Alastair Hewitt’s Novasaur was still something of an oddity.

In fact, unless you knew what it was ahead of time, you might not even recognize it as a computer. Certainly not a contemporary one, anyway. There’s nothing inside its Polycase ZN-40 enclosure that looks like a modern CPU, a bank of RAM, or a storage device. Those experienced with vintage machines would likely recognize the tight rows of Advanced Schottky TTL chips as the makings of some sort of computer that predates the 8-bit microprocessor, but its single 200 mm x 125 mm (8 in x 5 in) board seems far too small when compared to the 1970s machines that would have utilized such technology. So what is it?

Inspired by projects such as the Gigatron, Alastair describes the Novasaur as a “full-featured personal computer” built using pre-1980 components. In his design, 22 individual ICs stand in for the computer’s CPU, and another 12 are responsible for a graphics subsystem that can push text and bitmapped images out over VGA at up to 416 x 240. It has 512 K RAM,  256 K ROM, and is able to emulate the Intel 8080 fast enough to run CP/M and even play some early 80s PC games.

Better Living Through Emulation

Arguably the most noteworthy feature of the Novasaur is it’s ability to emulate a vintage CPU. By taking this approach, Alastair essentially ensured that the only software he’d ever technically have to write for the computer would be a hardware abstraction layer. Once that was in place, he could simply load up existing programs and operating systems that were designed to run on the emulated chip.

In comparison, other TTL computers generally need to have new applications written for them. To use the Gigatron as an example, the system’s ROM provides the user with a handful of tools and games that were written specifically for the hardware. But outside of that, your best bet for getting new software on the system would be to use the Tiny BASIC interpreter and write it yourself.

Intel 8080 Credit: Konstantin Lanzet [CC BY-SA 3.0]The Novasaur’s ability to run CP/M and existing Intel 8080 software makes it a far more practical machine than others we’ve seen in the past, and is central to the claim of it being a “full-featured personal computer” rather than just an experiment in computing minimalism. But interestingly, a look through the project log shows that the decision to go with the 8080 didn’t happen until relatively late in the game. Originally, Alastair was aiming for his machine to be compatible with something in Motorola’s 6800 family of chips, or perhaps some subset of the MOS 6502.

It would be almost a year later before he made a post explaining he’s decision to target the relatively overlooked RCA 1802 COSMAC. A month later, at the recommendation of Gigatron’s creator Marcel van Kervinck, he reevaluated the situation once more. Originally he’d been put off by the complexity of the Z80, but the Intel 8080 seemed to offer a reasonable middle-ground. As it takes his computer 137 cycles to complete one CPU instruction, Alastair says the final emulated CPU is operating at approximately 450 kHz, or around 22% as fast as the original hardware.

Living History

While the Novasaur is an incredible accomplishment itself, one also has to give credit to Alastair for the phenomenal documentation he’s put together. Since the beginning of 2019, he’s been documenting every step that’s gone into the planning, design, and construction of his TTL computer through log updates on the Hackaday.io page.

The fact that we can look back and see exactly what promoted him to switch gears and start focusing on Intel 8080 compatibility or what it looked like the first time the graphics system lit up a real CRT display, is an invaluable resource for others who might be working on similar systems. Of course even if you’re not looking to build a TTL computer of your own, it’s still fascinating to see how it all came together.

There’s some irony that, even though it was on display at the 2021 Vintage Computer Festival East, the Novasaur was almost certainly one of the newest pieces of hardware in the building. After all, the PCB just hit its final (for now, at least) revision over the summer.  Even still, there were few other machines that felt as truly personal as this labor of love, and I’m glad that VCF not only gave me the chance to see it up-close, but to meet its exceptionally passionate creator.

Source Here: hackaday.com

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Ham Radio Gets Brain Transplant

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Old radios didn’t have much in the way of smarts. But as digital synthesis became more common, radios often had as much digital electronics in them as RF circuits. The problem is that digital electronics get better and better every year, so what looked like high-tech one year is quaint the next. [IMSAI Guy] had an Icom IC-245 and decided to replace the digital electronics inside with — among other things — an Arduino.

He spends a good bit of the first part of the video that you can see below explaining what the design needs to do. An Arduino Nano fits and he uses a few additional parts to get shift registers, a 0-1V digital to analog converter, and an interface to an OLED display.

Unless you have this exact radio, you probably won’t be able to directly apply this project. Still, it is great to look over someone’s shoulder while they design something like this, especially when they explain their reasoning as they go.

The PCB, of course, has to be exactly the same size as the board it replaces, including mounting holes and interface connectors. It looks like he got it right the first time which isn’t always easy. Does it work? We don’t know by the end of the first video. You’ll have to watch the next one (also below) where he actually populates the PCB and tests everything out.

Source: hackaday.com

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Researchers Use Nanoparticles to Kill Dangerous Bacteria That Hide Inside Human Cells

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Researchers from the University of Southampton, working with colleagues at the Defence Science and Technology Laboratory (Dstl), have developed a new technology based on nanoparticles…

The post Researchers Use Nanoparticles To Kill Dangerous Bacteria That Hide Inside Human Cells appeared first on SciTechDaily.

Source: scitechdaily.com

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The Unofficial Guide to (Avoiding) Electrocution

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If you’re reading this sentence, there’s a pretty good chance that you interact with electricity more than just as an end-user. You’re a hacker. You aren’t afraid of a few volts, and your projects may involve both DC and AC voltage. Depending on what you’re working on, you might even be dealing with several thousand volts. And it’s you who Big Clive made the video below the break for.

“Familiarity breeds contempt” as the old saying goes, and the more familiar we are with electronics, the more cavalier we may tend to get. If we allow ourselves to get too lax, we may be found working on live circuits, skimping on safety for the sake of convenience, or jokingly saying “safety third!” far too often as we tear into a hazardous situation without scoping it out first.

Who better to bring us down to earth than Big Clive. In this video, he explains how electricity has the potential to impede the beating of our hearts, the action of our lungs, and even break bones. You’ll find a candid discussion about what electric shock does to a person, how to avoid it, and how to help if someone near you suffers electric shock.

Of course, if safety isn’t your thing, then maybe you’re ready to Shake Hands With Danger.

Original Article: hackaday.com

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