The Many-Sprites Interpretation Of Amiga Mechanics

December 31, 2025 by Bryan Cockfield 21 Comments

The invention of sprites triggered a major shift in video game design, enabling games with independent moving objects and richer graphics despite the limitations of early video gaming hardware. As a result, hardware design was specifically built to manipulate sprites, and generally as new generations of hardware were produced the number of sprites a system could produce went up. But [Coding Secrets], who published games for the Commodore Amiga, used an interesting method to get this system to produce far more sprites at a single time than the hardware claimed to support.

This hack is demonstrated with [Coding Secrets]’s first published game on the Amiga, Leander. Normally the Amiga can only display up to eight sprites at once, but there is a coprocessor in the computer that allows for re-drawing sprites in different areas of the screen. It can wait for certain vertical and horizontal line positions and then execute certain instructions. This doesn’t allow unlimited sprites to be displayed, but as long as only eight are displayed on any given line the effect is similar. [Coding Secrets] used this trick to display the information bar with sprites, as well as many backgrounds, all simultaneously with the characters and enemies we’d normally recognize as sprites.

Of course, using built-in hardware to do something the computer was designed to do isn’t necessarily a hack, but it does demonstrate how intimate knowledge of the system could result in a much more in-depth and immersive experience even on hardware that was otherwise limited. It also wasn’t free to use this coprocessor; it stole processing time away from other tasks the game might otherwise have to perform, so it did take finesse as well. We’ve seen similar programming feats in other gaming projects like this one which gets Tetris running with only 1000 lines of code.

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Microsoft’s WebTV Is Being Revived By Fans

December 30, 2025 by Maya Posch 12 Comments

During the 1990s, everyone wanted to surf the information super-highway — also known as the World Wide Web or just ‘Internet’ — but not everyone was interested in getting one of those newfangled personal computers when they already had a perfect good television set. This opened a market for TV-connected thin clients that could browse the web with a much lower entry fee, with the WebTV service being launched in 1996. Bought by Microsoft in 1997 and renamed MSN TV, it lasted until 2013. Yet rather than this being the end, the service is now being revived by members of the community through the WebTV Redialed project.

The DreamPi adds dial-up support back to old hardware.

The project, which was recently featured in a video by [MattKC], replaces the original back-end services that the thin clients connected to via their dial-up modems, with the first revision using a proprietary protocol. The later and much more powerful MSN TV 2 devices relied on a standard HTTP-based protocol running on Microsoft’s Internet Information Services (IIS) web server and Windows.

What’s interesting about this new project is that it allows you to not just reconnect your vintage WebTV/MSN TV box, but also use a Windows-based viewer and more. What difficulty level you pick depends on the chosen hardware and connection method. For example, you can pair the Raspberry Pi with a USB modem to get online thanks to the DeamPi project.

Interestingly, DreamPi was created to get the Sega Dreamcast back online, with said console also having its own WebTV port that can be revived this way. Just in case you really want to get the full Dreamcast experience.

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Only Known Copy Of UNIX V4 Recovered From Tape

December 29, 2025 by Maya Posch 43 Comments

UNIX version 4 is quite special on account of being the first UNIX to be written in C instead of PDP-11 ASM, but it was also considered to have been lost to the ravages of time. Joyfully, we can report that the more than fifty year old magnetic tape that was recently discovered in a University of Utah storeroom did in fact contain the UNIX v4 source code. As reported by Tom’s Hardware, [Al Kossow] of Bitsavers did the recovery by passing the raw flux data from the tape read head through the ReadTape program to reconstruct the stored data.

Since the tape was so old there was no telling how much of the data would still be intact, but fortunately it turned out that the tape was not only largely empty, but the data that was on it was in good nick. You can find the recovered files here, along with a README, with Archive.org hosting the multi-GB raw tape data. The recovered data includes the tape file in SimH format and the filesystem

Suffice it to say that you will not run UNIX v4 on anything other than a PDP-11 system or emulated equivalent, but if you want to run its modern successors in the form of BSD Unix, you can always give FreeBSD a shot.

Exploring Modern SID Chip Substitutes

December 23, 2025 by Maya Posch 13 Comments

The SIDKick Pico installed on a breadboard. (Credit: Ben Eater)

Despite the Commodore 64 having been out of production for probably longer than many Hackaday readers have been alive, its SID audio chip remains a very popular subject of both retrocomputing and modern projects. Consequently a range of substitutes have been developed over the decades, all of which seek to produce the audio quality of one or more variants of the SID. This raises the question of which of these to pick when at first glance they seem so similar. Fret not, for [Ben Eater] did an entire video on comparing some modern SID substitutes and his thoughts on them.

First is the SIDKick Pico, which as the name suggests uses a Raspberry Pi Pico board for its Cortex-M0+ MCU. This contrasts with the other option featured in the video, in the form of the STM32F410-based ARMSID.

While the SIDKick Pico looks good on paper, it comes with a number of different configurations, some with an additional DAC, which can be confusing. Because of how it is stacked together with the custom PCB on which the Pi Pico is mounted, it’s also pretty wide and tall, likely leading to fitment issues. It also doesn’t work as a drop-in solution by default, requiring soldering to use the SID’s normal output pins. Unfortunately this led to intense distortion in [Ben]’s testing leading him to give up on this.

Meanwhile the ARMSID is about as boring as drop-in replacements get. After [Ben] got the ARMSID out of its packaging, noted that it is sized basically identical to the original SID and inserted it into the breadboard, it then proceeded to fire right up with zero issues.

It’s clear that the SIDKick Pico comes with a lot of features and such, making it great for tinkering. However, if all you want is a SID-shaped IC that sounds like a genuine SID chip, then the ARMSID is a very solid choice.

Thanks to [Mark Stevens] for the tip.

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Retrocomputing: Simulacrum Or The Real Deal?

December 20, 2025 by Elliot Williams 35 Comments

The holidays are rapidly approaching, and you probably already have a topic or two to argue with your family about. But what about with your hacker friends? We came upon an old favorite the other day: whether it “counts” as retrocomputing if you’re running a simulated version of the system or if it “needs” to run on old iron.

This lovely C64esque laptop sparked the controversy. It’s an absolute looker, with a custom keyboard and a retro-reimagining-period-correct flaptop design, but the beauty is only skin deep: the guts are a Raspberry Pi 5 running VICE. An emulator! Horrors!

We’ll admit to being entirely torn. There’s something about the old computers that’s very nice to lay hands on, and we just don’t get the same feels from an emulator running on our desktop. But a physical reproduction like with many of the modern C64 recreations, or [Oscar Vermeulen]’s PiDP-8/I really floats our boat in a way that an in-the-browser emulation experience simply doesn’t.

Another example was the Voja 4, the Supercon 2022 badge based on a CPU that never existed. It’s not literally retro, because [Voja Antonics] designed it during the COVID quarantines, so there’s no “old iron” at all. Worse, it’s emulated; the whole thing exists as a virtual machine inside the onboard PIC.

But we’d argue that this badge brought more people something very much like the authentic PDP-8 experience, or whatever. We saw people teaching themselves to do something functional in an imaginary 4-bit machine language over a weekend, and we know folks who’ve kept at it in the intervening years. Part of the appeal was that it reflected nearly everything about the machine state in myriad blinking lights. Or rather, it reflected the VM running on the PIC, because remember, it’s all just a trick.

So we’ll fittingly close this newsletter with a holiday message of peace to the two retrocomputing camps: Maybe you’re both right. Maybe the physical device and its human interfaces do matter – emulation sucks – but maybe it’s not entirely relevant what’s on the inside of the box if the outside is convincing enough. After all, if we hadn’t done [Kevin Noki] dirty by showing the insides of his C64 laptop, maybe nobody would ever have known.

Reverse-Engineering The Intel 8087 Stack Circuitry

December 19, 2025 by Maya Posch 3 Comments

Although something that’s taken for granted these days, the ability to perform floating-point operations in hardware was, for the longest time, something reserved for people with big wallets. This began to change around the time that Intel released the 8087 FPU coprocessor in 1980, featuring hardware support for floating-point arithmetic at a blistering 50 KFLOPS. Notably, the 8087 uses a stack-based architecture, a major departure from existing FPUs. Recently [Ken Shirriff] took a literal closer look at this stack circuitry to see what it looks like and how it works.

Nearly half of the 8087’s die is taken up by the microcode frontend and bus controller, with a block containing constants like π alongside the FP calculation-processing datapath section taking up much of the rest. Nestled along the side are the eight registers and the stack controller. At 80 bits per FP number, the required registers and related were pretty sizeable for the era, especially when you consider that the roughly 60,000 transistors in the 8087 were paired alongside the 29,000 transistors in the 16-bit 8086.

Each of the 8087’s registers is selected by the decoded instructions via a lot of wiring that can still be fairly easily traced despite the FPU’s die being larger than the CPU it accompanied. As for the unique stack-based register approach, this turned out to be mostly a hindrance, and the reason why the x87 FP instructions in the x86 ISA are still quite maligned today. Yet with careful use, providing a big boost over traditional code, this made it a success by that benchmark, even if MMX, SSE, and others reverted to a stackless design.

Chip Swap Fixes A Dead Amiga 600

December 18, 2025 by Jenny List 12 Comments

The Amiga 600 was in its day the machine nobody really wanted — a final attempt to flog the almost original spec 68000 platform from 1985, in 1992. Sure it had a PCMCIA slot nobody used, and an IDE interface for a laptop hard drive, but it served only to really annoy anyone who’d bought one when a few months later the higher-spec 1200 appeared. It’s had a rehabilitation in recent years though as a retrocomputer, and [LinuxJedi] has a 600 motherboard in need of some attention.

As expected for a machine of its age it can use replacement electrolytic capacitors, and its reset capacitor had bitten the dust. But there’s more to that with one of these machines, as capacitor leakage can damage the filter circuitry surrounding its video encoder chip. Since both video and audio flow through this circuit, there was no composite video to be seen.

The hack comes in removing the original chip rather than attempt the difficult task of replacing the filter, and replacing it with a different Sony chip in the same series. It’s nicely done with a connector in the original footprint, and a small daughterboard. The A600 lives again, but this time it won’t be a disappointment to anyone.

If you want to wallow in some Amiga history as well as read a rant about what went wrong, we have you covered.