macintosh

62 Articles

34-Year-Old Macintosh ROM Bug Revealed By Emulator

December 7, 2025 by No comments

Generally, you’d hope that your computer manufacturer got the ROM just right before shipping your computer. As [Doug Brown] found out, Apple actually fumbled this with the release of the Macintosh Classic II several decades ago. And yet… the machines worked! That turns out to be due to a rather weird low-level quirk, as recent tinkering in an emulator revealed. 

The bug was revealed when [Doug] was experimenting with the emulated Macintosh Classic II in MAME. He was exploring keyboard shortcuts for launching the debugger, but soon found a problem. He needed to load MacsBug to enable the debugging shortcut, and that required the use of 32-bit addressing. However, the emulated system wouldn’t boot in this mode at all, instead landing on a Sad Mac error screen.

Heavy debugging ensued, which makes for great reading if you love to chase problems on an instruction-by-instruction basis. Ultimately, [Doug’s] conclusion was a mindboggling one. He determined that the crash in MAME came down to a difference between the emulator’s behaviour versus the original Motorola 68030 CPU in the Classic II. There was simply a problematic undocumented instruction baked into the ROM. The real CPU runs this undocumented instruction, which modifies a certain register, allowing boot without issue. Meanwhile, the emulated CPU tries to execute the bad instruction, fails to modify the right register, and everything falls in a heap. [Doug] speculates that had the 68030 CPU hadn’t hidden the bug, Apple’s engineers might have found it many years ago. He even proved his theory by whipping up multiple custom ROMs to verify what was going on.

We love it when bugs from decades past rear their heads; we love it even more when they get fixed. If you’re chasing down issues with an Amiga or you’re ironing out the kinks in software for the Acorn Archimedes, be sure to let us know on the tips line.

[via Tom’s Hardware, thanks to Jason Morris for the tip!]

The Fastest (68k) Macintosh Might Not Be An Amiga Anymore

November 15, 2025 by 19 Comments

Amiga and Atari fans used to lord over their Apple-eating brethren the fact that Cupertino never moved to the most advanced 68k processors — so for a while, thanks to 68060 accelerator cards, the fastest thing running Macintosh software was an Amiga (or Atari). After all these years, the Macintosh community is finally getting the last laugh, as [zigzagjoe] demonstrates an actual Macintosh booting with a 68060 CPU for the first time in a thread on 68KMLA. Video or it didn’t happen? Check it out below.

The Mac in question is a Quadra 650, which is a good choice since it was about the last thing Apple sold before switching to PowerPC, and ran the 68040 processor. [Reinauer] had already produced a 68040-to-68060 socket adapter (the two chips not being pinout compatible), so the hardware part of the battle was already set. Software, however? That was a different story, and where [zigzagjoe] put in the effort.

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Macintosh System 7 Ported To X86 With LLM Help

September 29, 2025 by 51 Comments

You can use large language models for all sorts of things these days, from writing terrible college papers to bungling legal cases. Or, you can employ them to more interesting ends, such as porting Macintosh System 7 to the x86 architecture, like [Kelsi Davis] did.

When Apple created the Macintosh lineup in the 1980s, it based the computer around Motorola’s 68K CPU architecture. These 16-bit/32-bit CPUs were plenty capable for the time, but the platform ultimately didn’t have the same expansive future as Intel’s illustrious x86 architecture that underpinned rival IBM-compatible machines.

[Kelsi Davis] decided to port the Macintosh System 7 OS to run on native x86 hardware, which would be challenging enough with full access to the source code. However, she instead performed this task by analyzing and reverse engineering the System 7 binaries with the aid of Ghidra and a large language model. Soon enough, she had the classic System 7 desktop running on QEMU with a fully-functional Finder and the GUI working as expected. [Kelsi] credits the LLM with helping her achieve this feat in just three days, versus what she would expect to be a multi-year effort if working unassisted.

Files are on GitHub for the curious. We love a good port around these parts; we particularly enjoyed these efforts to recreate Portal on the N64. If you’re doing your own advanced tinkering with Macintosh software from yesteryear, don’t hesitate to let us know.

The End Of The Hackintosh Is Upon Us

July 8, 2025 by 94 Comments

From the very dawn of the personal computing era, the PC and Apple platforms have gone very different ways. IBM compatibles surged in popularity, while Apple was able to more closely guard the Macintosh from imitators wanting to duplicate its hardware and run its software.

Things changed when Apple announced it would hop aboard the x86 bandwagon in 2005. Soon enough was born the Hackintosh. It was difficult, yet possible, to run MacOS on your own computer built with the PC parts your heart desired.

Only, the Hackintosh era is now coming to the end. With the transition to Apple Silicon all but complete, MacOS will abandon the Intel world once more.

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A Portable M4 Mac Mini

May 16, 2025 by 29 Comments

The Mac mini is the closest to an Apple-based SBC you can get, so it lends itself to unusual portable computers. [Scott Yu-Jan] is back to tackle a portable build using the latest and greatest M4 mini.

[Yu-Jan] walks us through his thought process of how to maximize the portability of the system without all that tedious mucking about with setting up a separate keyboard, monitor, and the mini while on the go. With the more complicated electronics, the monitor risked tipping the keyboard over when attached, particularly since [Yu-Jan] isn’t a fan of batteries for his portables.

By affixing the Mac mini to the side of the keyboard, it makes the whole thing easier to slip into a bag without being overly thick. We get a peek into his iterative process as well when he evaluates the build and decides that the closing of the lid wasn’t what he was hoping for. By adding some TPU rests for the monitor to rest on in the closed position, he says it’s really brought the whole project up a notch. We certainly have had our own projects where one little detail really moves it from sketchy to polished, and we appreciate when makers clue us in on where that happened for them.

You may recognize [Yu-Jan] from our previous coverage of his older portable all-in-one Mac mini and this luggable version where he explains why he doesn’t like laptops. If you like your computers more stationary, how about some G4 iMacs with the newer internals from an M-series mini?

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A Look Inside MacPaint

April 5, 2025 by 28 Comments

Usually when we talk about retrocomputing, we want to look at — and in — some old hardware. But [Z→Z] has a different approach: dissecting MacPaint, the Apple drawing program from the 1980s.

While the program looks antiquated by today’s standards, it was pretty hot stuff back in the day. Things we take for granted today were big deals at the time. For example, being able to erase a part of something you drew prompted applause at an early public demo.

We enjoyed the way the program was tested, too. A software “monkey” was made to type keys, move things, and click menus randomly. The teardown continues with a look inside the Pascal and assembly code with interesting algorithms like how the code would fill an area with color.

The program has been called “beautifully organized,” and [Z→Z] examines that assertion. Maybe the brilliance of it has been overstated, but it did work and it did influence many computer graphics programs over the years.

We love digging through old source code. Even old games. If you do your own teardowns, be sure to send us a tip.

Designing A Portable Mac Mini

March 25, 2025 by 8 Comments

When Apple first launched the Macintosh, it created a new sort of “Lunchbox” form factor that was relatively portable and very, very cool. Reminiscent of that is this neat portable Macintosh Mini, created by [Scott Yu-Jan].

[Scott] has created something along these lines before—putting an iPad dock on top of a Macintosh Studio to create a look vaguely reminiscent of the very first Macintosh computers. However, that build wasn’t portable—it wasn’t practical to build such a thing around the Macintosh Studio. In contrast, the Mac Mini is a lithe, lightweight thing that barely sups power—it’s much more suitable for a “luggable” computer.

The build relies on a 3D printed enclosure that wraps around the Mac Mini like a glove. Inside, there’s a chunky 20,800 mAh power bank with enough juice to run the computer for over three hours. Just like the original Mac, there’s a handle on top, too. The build’s main screen is actually an iPad Mini, hooked up to the Mac Mini. If you want to use it separately, it can be popped out just by pushing it via a cutout in the bottom of the enclosure.

[Scott] notes that it’s cool, but not exactly practical—it weighs seven pounds, mostly due to the weight of the heavy power bank. We’ve featured [Scott’s] stylish builds before, too, like this nice iPhone dock.

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