The IMac GPU Becomes Upgradeable, With PCIe

October 23, 2023 by Jenny List 11 Comments

Over its long lifetime, the Apple iMac all-in-one computer has morphed from the early CRT models through those odd table-lamp machines into today’s beautiful sleek affairs. They look pretty, but is there anything that can be done to upgrade them? Maybe not today’s ones, but the models from the mid-2000s can be given some surprising new life. [LowEndMac] have featured a 2006 24″ model that’s received a much more powerful GPU, something we’d have thought to be impossible.

The iMacs from that era resemble a monitor with a slightly chunkier back, in which resides the guts of the computer. By then the company was producing machines with an x86 processor, and their internals share a lot of similarities with a laptop of the period. The card is a Mac Radeon model newer than the machine would ever be used with, and it sits in a chain of mini PCIe to PCIe adapters. Even then it can’t drive the original screen, so a replacement panel and power supply are taken from another monitor and grafted into the iMac case. This along with a RAM and SSD upgrade makes this about the most upgraded a 2006 iMac could be.

Of course, another approach is to simply replace the whole lot with an Intel NUC.

A Quarter Century Of The IMac

August 18, 2023 by Jenny List 39 Comments

Growing older as an engineer turns out to be a succession of moments in which technologies and devices which you somehow still imagine to be cool or exciting, reveal themselves in fact to be obsolete, indeed, old. Such a moment comes today, with the25th anniversary of the most iconic of 1990s computers, Apple’s iMac. The translucent all-in-one machine was and remains more than simply yet another shiny Mac, it’s probably the single most influential home computer ever. A bold statement to be sure, but take a look at the computer you’re reading this on, indeed at all your electronic devices here in 2023, before you dismiss it.

Any colour you want, as long as it's beige — Any colour you want, as long as it’s beige. Leon Brooks, Public domain.

Computers in the 1990s were beige and boring. Breathtakingly so, a festival of the generic. If you had a PC it came in the same beige box as every single other PC, the only thing breaking the monotony being one of those LED 7-segment fake-MHz displays. Apple computers took the beige and ran with it, their PowerMac range being merely a smoother-fronted version of all those beige-box PCs. This was the period following the departure of Steve Jobs during which the company famously lost its way, and the Bondi blue Jonny Ive-designed iMac was the signature product of his triumphant return.

That’s enough pretending to have drunk the Apple Kool-Aid for one article, so why are we marking this anniversary? The answer lies not in the iMac’s hardware, though its 233MHz PowerPC G3 and ATI graphics driving a 15″ CRT were no slouch for the day, nor even in its forsaking of all their previous proprietary interfaces for USB. Instead it’s the design influence of this machine, as it ushered in a new era of technological devices whose ethos lay around how they might be used rather than in simply showering the interface with features. At the time the iMac spawned a brief fashion for translucent blue in everything from peripherals to steam irons, but in the quarter century since your devices have changed immeasurably in its wake. We still don’t like that weird round mouse though.

Header image: Rama, CC BY-SA 4.0.

Customizing The Start-Up Chime On A 1999 G3 IMac

March 19, 2023 by Maya Posch 3 Comments

The start-up chime on Macs is probably as recognizable as the default Nokia ringtone in this day and age. Yet much like a ringtone, so too one might want to change the start-up chime on a Mac. This is something which [Doug Brown] has done in the past already on a Power Mac G3 in 2012, which made him instantly an expert on the topic in the eyes of a reader who wanted to know how to change the chime on a 1999 iMac. While the firmware on both these systems is written in Forth, it did take a bit of sleuthing to figure out where the chime was hiding in the firmware image, and how to change it.

The target iMac is somewhat unique in that it has a G4 PPC CPU rather than the more common G3. The firmware is similar enough that it was a snap to simply search the newer iMac’s firmware for the signature of the chime sound data. This turned out to be the identical QuickTime IMA ADPCM format-encoded data, yet what was different was how this data was integrated into the firmware image. Key is finding the area in the firmware where not only the address of the chime data’s start is defined, but also its length. Finally, the checksums in the firmware image have to be updated so that it matches the patched data.

Reverse-engineering the checksum calculation in the Forth code turned out to be fairly straightforward, but getting the new firmware on the iMac turned out to be the biggest struggle, as [Doug] didn’t want to inflict running a manual firmware update onto this reader he was doing all this work for. This led [Doug] to do some more reverse-engineering using Ghidra to enable the use of the automatic updater like a regular firmware update.

In the end it all worked out great, and now another iMac no longer has the Mac chime on start-up.

A miniature iMac clone running MacOS Monterey

Cute Little IMac Clone Runs MacOS On A Tiny Screen

November 2, 2021 by Robin Kearey 6 Comments

Building a Hackintosh – a non-Apple computer running MacOS – has been a favorite pastime of hackers ever since Apple made the switch from PowerPC to Intel hardware. Though usually built from commodity PC parts, some have successfully installed Apple’s OS onto various kinds of Intel-based single-board computers. [iketsj] used such a board to build a cute little Hackintosh, and apparently decided that if he was going to imitate Apple’s hardware, he might as well take some clues from their industrial design. The result can be seen in the video (embedded below) where [Ike] demonstrates a tiny iMac-like device with a 5″ LCD screen.

The brains of this cute little all-in-one are a Lattepanda, which is a compact board containing an Intel CPU, a few GB of RAM and lots of I/O interfaces. [Ike] completed it with a 256 GB SSD, a WiFi/Bluetooth adapter and the aforementioned LCD, which displays 800×480 pixels and receives its image through the mainboard’s HDMI interface.

The case is a 3D-printed design that vaguely resembles a miniaturized iMac all-in-one computer. The back contains openings for a couple of USB connectors, a 3.5 mm headphone jack and even an Ethernet port for serious networking. A pair of speakers is neatly tucked away below the display, enabling stereo sound even without headphones.

The computer boots up MacOS Monterey just like a real iMac would, just with a much smaller display. [Ike] is the first to admit that it’s not the most practical thing in the world, but that he would go out and use it in a coffee shop “just for the lulz”. And we agree that’s a great reason to take your hacks outside.

[Ike] built a portable Hackintosh before, and we’ve seen some pretty impressive MacOS builds, like this Mini iMac G4, a beautiful Mac Pro replica in a trash can, and even a hackintosh built inside an actual Mac Pro case.

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An IMac All-In-One’s New Life

November 27, 2020 by Matthew Carlson 8 Comments

There’s a sleek form factor for desktop computers known as an “all-in-one” that enrobes a computer in a monitor. While the convenience of having all your computing in a neat package has some nice benefits, it comes with an unfortunate downside. Someday the computer inside is going to be old and outdated in comparison to newer machines. While a new OS goes a long way towards breathing life into an old machine, [Thomas] has decided to take the path less travelled and converted an old iMac all-in-one into a discrete monitor.

The iMac in question is the 20″ iMac G5 iSight (A1145) with an LG-Philips LM201W01-STB2 LCD panel. Looking back, [Thomas] would recommend just ordering an LCD driver controller kit from your favourite auction house. But for this particular modification, he decided to do things a little bit more manually and we’re quite glad he did.

Luckily for [Thomas], the panel supports TMDS (which both DVI and HDMI are compatible with). So the next step was to figure out the signalling wires and proper voltages. After some trouble caused by a mislabeled power line on the iMac PCB silk-screen (12v instead of 3.3v), he had all the wires identified and a plan starting to form. The first step was a circuit to trick the inverter into turning on with the help of a relay. The female HDMI plug with a breakout board was added and sticks out through the old firewire port. The minuscule wires in the display ribbon cable to the monitor were separated and soldered onto with the help of [Thomas’] daughter’s microscope. Resistances were checked as HDMI relies on impedance matched pairs. To finish it off, an old tactile toggle switch offers a way to turn the monitor on and off with a solid thunk.

We love seeing old hardware being repurposed for new things. This project nicely complements the iMac G4 Reborn With Intel NUC Transplant we saw earlier this year, as they both try to preserve the form factor while allowing a new computer to drive the display.

Mini IMac G4 Made With NUC And 3D Printer

November 10, 2020 by Lewin Day 5 Comments

Apple’s computers have been well regarded over the years for their sharp design features. Of course, something that’s great can only be cuter and cooler if it’s made even smaller. In just that vein, [Gary Olson] whipped up a 54% scale iMac G4.

The iMac G4 was the futuristic-looking flatscreen model, and the direct successor to the original CRT-based iMac. Unlike other projects that run Raspberry Pis or simply fit iPads inside, [Gary] elected to go for a Hackintosh-based build. The system runs Mac OS X on a Intel NUC kitted out with a Core i3 CPU. While it’s not a genuine PowerPC, using OS X fits the proper G4 aesthetic. The build relies on 3D printed components, with the scale size largely chosen to suit the size of [Gary’s] printer and the Intel NUC motherboard. [Gary] goes into detail explaining what was required to get the paint finish right and how to make the hinges stiff but movable.

We’re always fans of a mini retro builds, even if the fact that iMacs are now retro means we’re showing our age. If you’ve got your own cute micro PC coming together in the ‘shop, be sure to drop us a line!

Tiny Raspberry Pi Mac Nails The Apple Aesthetic

August 27, 2020 by Tom Nardi 35 Comments

We know that some in the audience will take issue with calling a Raspberry Pi in a 3D-printed case the “World’s Smallest iMac”, but you’ve got to admit, [Michael Pick] has certainly done a good job recreating the sleek look of the real hardware. While there might not be any Cupertino wizardry under all that PLA, it does have a properly themed user interface and the general aversion to external ports and wires that you’d expect to see on an Apple desktop machine.

The clean lines of this build are made possible in large part by the LCD itself. Designed specifically for the Raspberry Pi, it offers mounting stand-offs on the rear, integrated speakers, a dedicated 5 V power connection, and a FFC in place of the traditional HDMI cable. All that allows the Pi to sit neatly on the back of the panel without the normal assortment of awkward cables and adapters going in every direction. Even if you’re not in the market for a miniature Macintosh, you may want to keep this display in mind for your future Pi hacking needs.

Despite this clean installation, the diminutive Raspberry Pi was still a bit too thick to fit inside the 3D-printed shell [Michael] designed. So he slimmed it down in a somewhat unconventional, but admittedly expedient, way. With a rotary tool and a steady hand, he simply cut the double stacked USB ports in half. With no need for Ethernet in this build, he bisected the RJ-45 connector as well. We expect some groans in the comments about this one, but it’s hard to argue that this isn’t a hack in both the literal and figurative sense.

We really appreciate the small details on this build, from the relocated USB connectors to the vent holes that double as access to the LCDs controls. [Michael] went all out, even going so far as to print a little insert for the iconic Macintosh logo on the front of the machine. Though given the impressive work he put into his miniature “gaming PC” a couple months back, it should come as no surprise; clearly this is a man who takes his tiny computers very seriously.

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