I used Apple's ROM diagnostics to find a broken RAM trace on my Performa 450 after the chimes of death. Pretty nifty! www.downtowndougbrown.com/2025/12/find...

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

The bad news: I don't get to share video footage of my IIsi PSU frying. The good news: it's fixed! Even though I wasn't feeling optimistic after the first Q101 and D104 replacement failed, I tried again and it worked. The difference: this time, I didn't try to power it up with the dim bulb tester.

My IIsi power supply is proving to be tricky. I put in a new MOSFET and Zener, and this at least restored it to a state where it doesn’t blow the fuse when I plug it in. Good +5VSB too. Tried to turn it on, and it failed again and something’s shorted again. :-(

This is not a time machine. Blowing the fuse in my IIsi PSU gave me an excuse to finish putting my IIci/IIsi PSU tester into a nice enclosure. Pretty proud of this! First time I’ve made a case like this that wasn’t 3D printed. Although I did need to design and 3D print some internal brackets.

Got out the toaster oven and built up some IIsi PSU daughterboards today. First two test out perfect. The third…I turn it on and kablooey! Visible spark and F101 blows on my power supply. Dang, this is what I was worried about. Hard to test these without risking my PSU. Hope it’s not shot.

If you're getting tired of hearing about my IIsi riser board replica, never fear! It's coming to a close! My design is now live on GitHub. Built with all new components from Digi-Key except the two obsolete ICs. Still deciding how to build/sell them to recoup some costs. github.com/dougg3/iisi-...

Okay, my IIsi riser board replica is looking good. Everything will be uploaded to GitHub shortly, and I'll figure out a way to offer them for sale for convenience. As for the failure: it was a bad solder joint on pin 10 of the chip. @48kram.bsky.social had the closest guess and is the winner!

Built up my first IIsi power daughterboard replica. It looks nice, but it doesn’t work! The power supply immediately shuts off like it’s going into protection. Dang. I did end up with random tiny solder balls here and there from the paste. Could just be a soldering mistake.

Remember my research into the “lost” Performa 550 recovery partition? This hard drive arrived today, and it also has the partition! Even better, all the original Performa software is still on it too. This should hopefully solve the mystery of how the partition was originally created.

I probably won’t get around to building a replica up and trying it in my IIsi until this weekend, but look what arrived today!

Getting closer to trying out my replica design…just waiting on PCBs to arrive.

I'm making some pretty good progress on a Mac IIsi power supply riser board recreation design. With how much effort I've put into understanding the schematics, why not? Plus, having it all in KiCad will make it easier to understand for people going forward.

So I did this yesterday in an effort to fix my IIsi. It works fine, but there's something wrong with the soft power circuit because when I tell it to shut down, I hear the relay click but then it turns right back on. Removing every component and cleaning everything didn't fix it! I'm at a loss now.

Pierre found the Paula Abdul Easter Egg that caused the Power Mac 8100/110 to be delayed back in the day! Apple accidentally left PowerPC Enabler 1.1, the version with the egg, on a Spanish Disk Tools disk. I figured out that the newer 6100/7100/8100 ROM was the key to activating it.

Do old hard drives self-lubricate? This 80 MB Quantum drive from a Mac Performa worked, but it made a very loud spinning sound. I just let it run for a while, upside down some of the time. Now it's nice and quiet. The rubber bumper will go bad eventually, but I'm pleasantly surprised.

Finally recapped my store demo unit Performa 410 and got it working...but not without some drama. It gave me the chimes of death. Hooked up a serial cable and got the diagnostics data from it, which said it was an Egret error ($0030). Cleaned the heck out of that part of the board, and it works now!

Un autre Easter Egg découvert dans un Power Mac, avec Paula Abdul www.journaldulapin.com/2025/07/01/e...

I partially reballed this eMMC chip...by hand. No stencil. Just sticky flux, 0.3 mm solder balls, tweezers, a microscope, and a hot air station. Each solder ball was about the size of a grain of sand. Somehow I did it, and it was enough to read out the contents using my T56 programmer!

Ars Technica covered the G3 easter egg story, which is too cool! Pretty funny: a huge chunk of the comments on the article ended up being an off topic discussion about whether punctuation belongs inside or outside of a quote: "secret ROM image." vs. "secret ROM image".

with hints from (Downtown) Doug Brown, we just discovered the trigger for the beige powermac G3's secret ROM image: go to the Memory control panel, set up a RAM disk, reboot to mount it, go Special → Erase Disk and name the volume `secret ROM image` — you'll get a file `The Team` at its root […]

^alex in Libera #mac68k and I discovered a new (we think) Beige Power Mac G3 easter egg! Format the RAM disk with the name "secret ROM image" and it will create a JPEG file called "The Team" inside. @dandu.be had already found the JPEG image in the ROM in 2014, but now we know how to reveal it!

When the green light is red, it's charging. When the green light is green, it's finished.

Had a fun little visitor tonight. “Oh hello, I was wondering if you could show me how to get the Tanooki Suit in World 4-5 of Super Mario Bros. 3”

Oh wow, I forgot I still had this. Unopened Color StyleWriter Pro black ink cartridge. Wonder if it’s all dried up?

Il m'a fallu 6 ans, mais j'ai trouvé la ROM japonaise du Macintosh Plus. Elle n'était pas disponible sur le Net et elle contient une police avec les kanjis directement en ROM, ce qui accélère le démarrage du Macintosh Plus avec un OS japonais. www.journaldulapin.com/2025/05/17/r...

I just shared the story of how back in 2013, I fixed the bug in Basilisk II that caused it to fail with a black screen on Windows Vista and 7. Spoiler alert: it wasn’t Windows’ fault. www.downtowndougbrown.com/2025/05/how-...

I finally found some time to share this drive image of System 7.1P3 from the Performa 410 I bought earlier this year. 7.1P3 was previously undumped. It's not perfect, but I don't think we'll find a perfect restore until someone locates and dumps the Market Software Series Volume 1 CD.

My Mac Classic II’s reset button is corroded and doesn’t work. Thanks to the SE/30 reloaded BOM, I found it’s just a readily available Alps tact switch in a plastic carrier to make it right-angle. Yay!

Here's a link where I uploaded the Performa store demo to the Garden so that everyone can play with it. It works in Basilisk II and real hardware. It hangs in MAME. Infinite Mac seems to have a problem locating one of the files. I suspect it's because it has a slash in the name, but I'm not sure.

Last chance! 🕘 Want a cool clear case for your Mac SE or SE/30? The MacEffects kickstarter ends in under 2 hours! www.kickstarter.com/projects/mac...

I promise I'm not trying to turn into "the guy who posts about nothing but Mac Performas on bsky", but it appears that I've accidentally stumbled upon a piece of Apple's store demo software. It helps me choose whether to buy a 410 or 466 and teaches me how to use a mouse. More stuff to preserve...

Vous pensiez que Mac OS X Lion avait introduit la partition de restauration dans les Mac ? En fait, Apple en avait une dans les années 90 avec le Performa 550 et @downtowndougbrown.com a réussi à la retrouver www.journaldulapin.com/2025/03/24/r...

It's kind of fun looking at how random Mac UI elements evolved over time. One of the changes listed between System 7.1P5 and 7.1P6 was "Improved incorrect shut-down dialog." Seems like the language in the newer version was a little bit "nicer" about it.

Although it wasn't worth writing about, my crazy search for hard drives also led me to find the older caddy-loading Performa 550's original software bundle. I distinctly remember mine in the '90s having Monopoly too. This is earlier than the 7.1P6 restore CD that everyone uses.

I wonder how upset people in 1994 would have been if they realized Apple was leaving 3.6 MB of space on their 160 MB hard drive unused? And really, more like 6 MB considering the recovery partition was empty after restoring from CD.

I finally had some time to write up my blog post about finding the Macintosh Performa 550's hidden recovery partition in the wild. I also uploaded it to Macintosh Garden so it will be preserved forever! There are still some open questions - check your 550s! www.downtowndougbrown.com/2025/03/appl...

I just realized that in the special Performa version of Apple HD SC Setup (7.2.2P) on the System 7.1P5 Utilities disk, Apple accidentally forgot to turn off debug symbols! So the function names are intact. Could be useful for anybody doing reverse engineering. Left: 7.2.2. Right: 7.2.2P.

I recently received a PowerBook 170 with a dead drive that potentially have some unarchived drivers software on it. Does anyone have a Conner CP2045 that they might be willing to part with in the interest of software preservation?

This is the Utilities disk that came with my childhood Performa. Today I discovered it was acting up, and I was able to fix it! Ran an old hard drive magnet over it several times in a circle, then restored it from the original DC42 on the December 1993 dev CD. It works! Now…will the fix hold up?

I like to live dangerously. 7.5.4 is the system version that Apple released for a very short time and then pulled, replacing it with 7.5.5.

Found this local-ish to me, in great condition! The hard drive was reformatted in 1998, so it provides no extra knowledge of the recovery partition stuff. But…this looks exactly like the 550 I grew up with — the older caddy-loading model. Happy to have it!

I've still got it!

A great read on proving the Mac Classic II ROM contains a bug that unintentionally relies on an undocumented 68030 instruction to allow the machine to boot and not crash. www.downtowndougbrown.com/2025/01/the-...

Here's another sneak peek at the Performa 550's automatic OS recovery process. This is what you get when it boots up after the recovery.

So this happened today. Bet you've never seen this screen before. This is from a Performa 550. More details later...and of course software preservation!

Did you know that the Welcome to Macintosh screen is technically a system error dialog? It's also known as dsGreeting. The "ds" stands for deep shit. I'm not kidding...

Here's a sneak peek at some of the ROM hacking craziness I've been doing with the Mac Classic II that I recently bought. I've got an interesting story to tell, blog post about it hopefully coming in the next few days.

Thanks Adobe Reader, that was really insightful. 🙄 (It ended up being on sheet 3)