A hand holding a One ROM with a Commodore 64 in the background

One ROM: The Latest Incarnation Of The Software Defined ROM

September 3, 2025 by 24 Comments

Retrocomputers need ROMs, but they’re just so read only. Enter the latest incarnation of [Piers]’s One ROM to rule them all, now built with a RP2350, because the newest version is 5V capable. This can replace the failing ROMs in your old Commodore gear with this sweet design on a two-layer PCB, using a cheap microcontroller.

[Piers] wanted to use the RP2350 from the beginning but there simply wasn’t space on the board for the 23 level shifters which would have been required. But now that the A4 stepping adds 5 V tolerance [Piers] has been able to reformulate his design.

The C64 in the demo has three different ROMs: the basic ROM, kernel ROM, and character ROM. A single One ROM can emulate all three. The firmware is performance critical, it needs to convert requests on the address pins to results on the data bus just as fast as it can and [Piers] employs a number of tricks to meet these requirements.

The PCB layout for the RP2350 required extensive changes from the larger STM32 in the previous version. Because the RP2350 uses large power and ground pads underneath the IC this area, which was originally used to drop vias to the other side of the board, was no longer available for signal routing. And of course [Piers] is constrained by the size of the board needing to fit in the original form factor used by the C64.

The One ROM code is available over on GitHub, and the accompanying video from [Piers] is an interesting look into the design process and how tradeoffs and compromises and hacks are made in order to meet functional requirements.

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Field Guide To North American Crop Irrigation

September 3, 2025 by 26 Comments

Human existence boils down to one brutal fact: however much food you have, it’s enough to last for the rest of your life. Finding your next meal has always been the central organizing fact of life, and whether that meal came from an unfortunate gazelle or the local supermarket is irrelevant. The clock starts ticking once you finish a meal, and if you can’t find the next one in time, you’ve got trouble.

Working around this problem is basically why humans invented agriculture. As tasty as they may be, gazelles don’t scale well to large populations, but it’s relatively easy to grow a lot of plants that are just as tasty and don’t try to run away when you go to cut them down. The problem is that growing a lot of plants requires a lot of water, often more than Mother Nature provides in the form of rain. And that’s where artificial irrigation comes into the picture.

We’ve been watering our crops with water diverted from rivers, lakes, and wells for almost as long as we’ve been doing agriculture, but it’s only within the last 100 years or so that we’ve reached a scale where massive pieces of infrastructure are needed to get the job done. Above-ground irrigation is a big business, both in terms of the investment farmers have to make in the equipment and the scale of the fields it turns from dry, dusty patches of dirt into verdant crops that feed the world. Here’s a look at the engineering behind some of the more prevalent methods of above-ground irrigation here in North America.

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The Nintendo Famicom Reimagined As A 2003-era Family Computer

September 3, 2025 by 4 Comments

If there’s one certainty in life, it is that Nintendo Famicom and similar NES clone consoles are quite literally everywhere. What’s less expected is that they were used for a half-serious attempt at making an educational family computer in the early 2000s. This is however what [Nicole Branagan]  tripped over at the online Goodwill store, in the form of a European market Famiclone that was still in its original box. Naturally this demanded an up-close investigation and teardown.

The system itself comes in the form of a keyboard that seems to have been used for a range of similar devices based on cut-outs for what looks like some kind of alarm clock on the top left side and a patched over hatch on the rear. Inside are the typical epoxied-over chips, but based on some scattered hints it likely uses a V.R. Technology’s VTxx-series Famiclone. The manufacturer or further products by them will sadly remain unknown for now.

While there’s a cartridge slot that uses the provided 48-in-1 cartridge – with RAM-banked 32 kB of SRAM for Family BASIC – its compatibility with Famicom software is somewhat spotty due to the remapped keys and no ability to save, but you can use it to play the usual array of Famicom/NES games as with the typical cartridge-slot equipped Famiclone. Whether the provided custom software really elevates this Famiclone that much is debatable, but it sure is a fascinating entry.

Reverse-Engineering Mystery TV Equipment: The Micro-Scan

September 3, 2025 by 12 Comments

[VWestlife] ended up with an obscure piece of 80s satellite TV technology, shown above. The Micro-Scan is a fairly plan metal box with a single “Tune” knob on the front. At the back is a power switch and connectors for TV Antenna, TV Set, and “MW” (probably meaning microwave). There’s no other data. What was this, and what was it for?

Satellite TV worked by having a dish receive microwave signals, but televisions could not use those signals directly. A downconverter was needed to turn the signal into something an indoor receiver box (to which the television was attached) could use, allowing the user to select a channel to feed into the TV.

At first, [VWestlife] suspected the Micro-Scan was a form of simple downconverter, but that turned out to not be the case. Testing showed that the box didn’t modify signals at all. Opening it up revealed the Micro-Scan acts as a combination switchbox and variable power supply, sending a regulated 12-16 V (depending on knob position) out the “MW” connector.

So what is it for, and what does that “Tune” knob do? When powered off, the Micro-Scan connected the TV (plugged into the “TV Set” connector) to its normal external antenna (connected to “TV Antenna”) and the TV worked like a normal television. When powered on, the TV would instead be connected to the “MW” connector, probably to a remote downconverter. In addition, the Micro-Scan supplied a voltage (the 12-16 V) on that connector, which was probably a control voltage responsible for tuning the downconverter. The resulting signal was passed unmodified to the TV.

It can be a challenge to investigate vintage equipment modern TV no longer needs, especially hardware that doesn’t fit the usual way things were done, and lacks documentation. If you’d like to see a walkthrough and some hands-on with the Micro-Scan, check out the video (embedded bel0w).

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An Amiga Demo With No CPU Involved

September 2, 2025 by 27 Comments

Of the machines from the 16-bit era, the Commodore Amiga arguably has the most active community decades later, and it’s a space which still has the power to surprise. Today we have a story which perhaps pushes the hardware farther than ever before: a demo challenge for the Amiga custom chips only, no CPU involved.

The Amiga was for a time around the end of the 1980s the most exciting multimedia platform, not because of the 68000 CPU it shared with other platforms, but because of its set of custom co-processors that handled tasks such as graphics manipulation, audio, and memory. Each one is a very powerful piece of silicon capable of many functions, but traditionally it would have been given its tasks by the CPU. The competition aims to find how possible it is to run an Amiga demo entirely on these chips, by using the CPU only for a loader application, with the custom chip programming coming entirely from a pre-configured memory map which forms the demo.

The demoscene is a part of our community known for pushing hardware to its limits, and we look forward to seeing just what they do with this one. If you have never been to a demo party before, you should, after all everyone should go to a demo party!

Amiga CD32 motherboard: Evan-Amos, Public domain.

Screenshot of Lazarus IDE on MacOS Ventura

The Case For Pascal, 55 Years On

September 2, 2025 by 51 Comments

The first version of Pascal was released by the prolific [Niklaus Wirth] back in 1970. That’s 55 years ago, an eternity in the world of computing. Does anyone still use Pascal in 2025? Quite a few people as it turns out, and [Huw Collingbourne] makes the case why you might want to be one of them in a video embedded below.

In all fairness, when [Huw] says “Pascal” he isn’t isn’t talking about the tiny language [Wirth] wrote back when the Apollo Program was a going concern. He’s talking about Object Pascal, as either Free Pascal or Delphi– which he points out are regularly the tenth most popular of all programming languages. (Index.dev claims that it has climbed up to number nine this year, just behind Go.) As a professional move, it might not be the most obvious niche but it might not be career suicide either. That’s not his whole argument, but it’s required to address the criticism that “nobody uses Pascal anymore”.

Pascal, quite simply, can make you a better programmer. That, as [Huw] points out, was an explicit goal of the language. Before Python took over the education world, two generations of high school students learned Pascal. Pascal’s strong typing and strict rules for declaration taught those kids good habits that hopefully carried over to other languages. It might help you, too.

For experienced programmers, Pascal is still a reasonable choice for cross-platform development. Free Pascal (and the Lazarus IDE) brings the graphical, drag-and-drop ease that once made Delphi rule the Windows roost to any modern platform. (And Delphi, a commercial Pascal product, is apparently still around.) Free Pascal lets you code on Linux or Mac, and deploy on Windows, or vice-versa. While you could do that on Python, Pascal gets you a lot closer to the metal than Python ever could.

Sure, it’s a modern object-oriented language now, with objects and classes and hierarchies and all that jazz– but you don’t always have to use them. If you want to go low-level and write your Pascal like it’s 1985, you can. It’s like being able to switch into C and manipulate pointers whenever you want.

On some level, perhaps the answer to the question “Why use Pascal in 2025” is simply– why not? It’s likely that the language can do what you want, if you take the time to learn how. You can even use it on an Arduino if you so wish– or go bare metal on the Raspberry Pi.

Thanks to [Stephen Walters] for the tip.

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