Amiga, Interrupted: A Fresh Take On Amiga OS

August 19, 2024 by Heidi Ulrich 20 Comments

Serena OS is not just another operating system—it’s a playground for hackers, tinkerers, and Amiga enthusiasts pushing vintage hardware to new limits. Born from modern design principles and featuring pervasive preemptive concurrency and multi-user support, [dplanitzer]’s Serena OS is far from ordinary.

Running on Amiga systems with a 68030 or better CPU, it challenges traditional OS concepts by ditching threads in favor of dispatch queues, akin to Apple’s Grand Central Dispatch. The result? A dynamic, flexible kernel that combines forward-thinking design with retro charm.

The real innovation in Serena is its kernel, which uses a virtual processor concept to manage system resources efficiently. Instead of threads, Serena dynamically adjusts a pool of virtual processors based on dispatch queue needs, ensuring tasks are executed with precision and speed. Interrupt handling is also unique: interrupts are converted into semaphore signals, allowing the code to handle these signals at its convenience without missing any, making hardware interactions more controlled, especially where timing is critical.

For Amiga enthusiasts already customizing their setups, Serena OS offers new possibilities. It shares some spirit with projects like AROS (Amiga Research Operating System) but adds its own twist with object-oriented design and cross-platform goals. Whether you’re developing software for your classic Amiga or exploring new hardware interfaces, Serena OS provides a robust and adaptable foundation.

Scratch Built Amiga 2000 Stacks Up The Mods

March 8, 2023 by Tom Nardi 8 Comments

Around these parts, we most often associate [Drygol] with his incredible ability to bring damaged or even destroyed vintage computers back to life with a seemingly endless bag of repair and restoration techniques. But this time around, at the request of fellow retro aficionado [MrTrinsic], he was given a special assignment — to not only build a new Amiga 2000 from scratch, but to pack it with so many mods that just physically fitting them into the case would be a challenge in itself.

The final product, dubbed Tesseract, took two and a half years to complete and has been documented over the course of six blog posts. The first step was to get a brand new motherboard, in this case a modern recreation designed by Floppie209, and start populating it with components. With some modifications, the new board slipped neatly into a slick metal case. Unfortunately it quickly became clear some of the mods the duo wanted to install wouldn’t work with the reverse-engineered motherboard. This was around Spring of 2021, which is the last time we checked in on the project. Continue reading “Scratch Built Amiga 2000 Stacks Up The Mods” →

The Amiga 2000 You Always Wanted

May 2, 2021 by Jenny List 31 Comments

Back in the late 1980s, Commodore pulled the masterstroke of selling several models and generations of Amiga that were all powered by essentially the same speed 68000 and associated chipset. Sure, there were differences in the RAM and other options you could fit and later models had a few extra graphics modes. Still, the entry-level A500 did substantially the same as the high-end A2000. No matter, we the fans all wanted a 2000 anyway, though we typically found ourselves unable to afford one. It’s 2021 now though, so if you never achieved the dream of owning your own A2000, now you can build one of your own! It’s the task [Drygol] has taken on, with an A2000 made entirely from new components, save for a few salvaged Commodore-specific chips and connectors.

At its heart is a beautiful recreation of the original PCB that we’re guessing will be of great interest to owners whose NiCd batteries have leaked and corroded their originals. It’s all through-hole, but the sheer size of a motherboard still makes it a daunting prospect to solder by hand. There are a huge quantity of decoupling and ESD components that all have to be held with tape before the board is flipped over for soldering, and then all the chips are socketed. A Fat Agnes address generator was fitted on a RAM expansion daughterboard, leading to some significant problems as it proved not to be compatible and had to be removed.

The whole is put in a very low-profile PC case with appropriate risers for the Zorro slots, and then in goes a set of upgrades probably not seen in the same place since about 1993. We don’t recognize them all, but we can see accelerators, a floppy emulator, an HDD emulator using a CF card, and is that a network card we spy? This machine is still a work in progress, but we can guarantee it would have been an extreme object of desire thirty years ago. See it in action in the video below the break.

If rebuilding an Amiga interests you, we took a look at the state of the remanufactured parts scene for the platform last year.

Continue reading “The Amiga 2000 You Always Wanted” →

Smashed Amiga 2000 Gets New Lease On Life

April 2, 2021 by Tom Nardi 9 Comments

For most people, opening up a package and seeing that the Amiga 2000 you purchased on eBay had been smashed up by the delivery carrier would be a heartbreaking moment. But not [Drygol]. If you live and breathe vintage computer restorations like he does, finding your latest acquisition is in need of more repairs and upgrades than you originally anticipated is actually a bonus.

The first issue that needed sorting out was the broken case. This Amiga must have had one wild ride, as there were several nasty cracks in the front panel and whole chunks had been broken off. We’ve seen [Drygol] repair broken computer cases before, but it seems like each time he comes up with some new tricks to bring these massacred pieces of plastic back to like-new condition. In this case plastic welding is used to hold the parts together and fill in the gaps, and then brass mesh is added to the backside for strength. The joints are then sanded, filled in with polyester putty, and finally sprayed with custom color matched paint. While he was in the area, he also filled in a hole the previous owner had made for a toggle switch.

Before

After

Then [Drygol] moved onto the internals. Some of the traces on the PCB had been corroded by a popped battery, a socket needed to be replaced, and as you might expect for a machine of this vintage, all of the electrolytic capacitors were suspect and needed to go. Finally, as the system didn’t have a power supply, he wired in a picoPSU. That got the 34 year old computer back up and running, and at this point, the machine was almost like new again. So naturally, it was time to start with the upgrades and modifications.

[Drygol] added an IDE interface and connected a CompactFlash adapter as the computer’s primary drive. For the secondary, he installed a GoTek floppy drive emulator that lets you replace a mountain of physical disks with a USB flash drive full of images. Between the two, all of the computer’s storage needs are met with nary a moving part.

The emulator was given its own 3D printed front panel to fit with the Amiga’s visual style, and he also printed out a holder for the RGB4ALL S-Video/Composite adapter installed on the rear of the machine. To help keep all this new gear cool, he finished things off with a new case fan.

Some will no doubt complain about the addition of the extra gadgetry, but to those people, we suggest you just focus on the phenomenal case restoration work. While you might not agree with all of the modifications [Drygol] makes, there’s no question that you can learn something by going through his considerable body of work.

Amiga Repairs Put One Tough Little Machine Back In Service

July 30, 2018 by Dan Maloney 8 Comments

Returning a piece of retro hardware to factory condition is generally a labor of love for the restorationist. A repair, on the other hand, is more about getting a piece of equipment back into service. But the line between repair and restoration is sometimes a fine one, with the goals of one bleeding over into the other, like in this effort to save an otherwise like-new Amiga 2000 with a leaky backup battery.

Having previously effected emergency repairs to staunch the flow of electrolyte from the old batteries and prevent further damage, [Retromat] entered the restoration phase of the project. The creeping ooze claimed several caps and the CPU socket as it spread across the PCB, but the main damage was to the solder resist film itself. In the video below you can clearly see flaky, bubbly areas in the mask where the schmoo did its damage.

Using a fiberglass eraser, some isopropyl alcohol, and far more patience than we have, [Retromat] was able to remove the damaged resist to reveal the true extent of the damage below. Thankfully, most of the traces were still intact; only a pair of lines under the CPU socket peeled off as he was removing it. After replacing them with fine pieces of wire, replacing the corroded caps and socket, and adding a coin-cell battery holder to replace the old battery, the exposed traces were coated with a varnish to protect them and the machine was almost as good as new.

Amigas were great machines in their day and launched more than one business. They’ve proved their staying power too, some even in mission-critical roles.

Continue reading “Amiga Repairs Put One Tough Little Machine Back In Service” →

Amiga 2000 Emergency Repair

July 8, 2018 by Al Williams 20 Comments

Big companies spend small fortunes on making sure their computers stay running and that they can be repaired quickly in an emergency. You wouldn’t expect an emergency repair on an Amiga 2000, though. [RETR-O-MAT] bought an Amiga 2000 that did boot, but was known to have a leaky battery on the motherboard. He wanted to rush to replace the battery before the leakage caused serious damage. You can see all this in the video below.

The computer looked lightly used over its 32-year lifespan, even when the case came off. The battery corrosion was evident, though. Even the bolt holding down the motherboard was clearly corroded from the leaking battery, causing it to be very difficult to remove.

The battery leakage also made unsoldering the battery a challenge. Several chips and sockets — including the CPU — were affected, so they had to come out. You can see a nice demonstration of the “old screwdriver trick” which might be eye-opening if you’ve only worked with SMD chips.

Even if you don’t care much about the Amiga 2000, it is interesting to see inside an old computer like this and note the differences — and similarities — to modern designs. The video is as much a tear down as it is a repair story. It also might be useful if you ever face having to tear out a leaky battery on any piece of gear. Continue reading “Amiga 2000 Emergency Repair” →

Amiga Zorro HDMI Graphics Card Hits The Market

December 10, 2016 by Jenny List 19 Comments

If you were a computer enthusiast in the late 1980s or early 1990s, the chances are that one of your objects of desire would have been a Commodore Amiga. These machines based on the 68000 line of processors and a series of specialized co-processors offered the best compromise between performance and affordability at the time, with multitasking, a GUI, and graphics capabilities that were streets ahead of their competition.

The Amiga story is littered with tales of what might have been, as dismal marketing and lacklustre product refreshes caused it to lurch from owner to owner and eventually fade away from the mainstream in the mid 1990s. But it’s been one of those products that never really died, as a band of enthusiasts have kept a small market for its software and hardware alive.

Workbench as you may not have seen it before.

Earlier this year we showed you a prototype of an unusual graphics card, a modern GPU implemented on an FPGA board that brought up-to-date HDMI monitor support to the Zorro expansion slots found in the big-box Amigas. It’s thus very interesting today to find that the board made it to market, and that you can buy one for your Amiga if you have a spare 189 Euros (now sold out but taking pre-orders for another production run). Producing any niche electronic product is a significant challenge, so it is always positive to see one that makes it.

As well as HDMI output the board features a micro SD card slot that is mountable as an Amiga volume, and an expansion header that is toured as “Hacker friendly”. Best of all though, the whole board is open-source with all resources on a GitHub repository, so as well as reading our coverage of the prototype you can immerse yourself in its internals if that is your thing.

It’s always good to see a new piece of hardware for an old computer see the light of day, though it’s fair to say this development won’t revive the Amiga platform in the way that the Raspberry Pi has for RiscOS. Still, the mere fact of an open-source Zorro FPGA implementation being released should mean that other cards become possible, so we await developments with interest.

[via forums.xilinx.com]