Doug Brown
@downtowndougbrown.com
Classic Mac geek, Linux geek, blogger, embedded firmware developer, Blazers fan.
https://www.downtowndougbrown.com/
https://www.downtowndougbrown.com/
Reposted by Doug Brown
The Fastest (68k) Macintosh Might Not Be an Amiga Anymore
The Fastest (68k) Macintosh Might Not Be an Amiga Anymore
Hackaday Article
hackaday.com
November 16, 2025 at 6:04 AM
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.
October 5, 2025 at 8:54 PM
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. :-(
September 14, 2025 at 1:17 AM
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.
September 1, 2025 at 5:18 PM
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.
August 30, 2025 at 10:36 PM
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-...
GitHub - dougg3/iisi-riser-board: Replica of Macintosh IIsi power supply riser board model AP41S
Replica of Macintosh IIsi power supply riser board model AP41S - dougg3/iisi-riser-board
github.com
August 27, 2025 at 2:39 AM
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!
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!
August 25, 2025 at 10:52 PM
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!
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.
August 24, 2025 at 12:27 AM
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.
August 22, 2025 at 10:54 PM
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!
August 18, 2025 at 11:15 PM
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.
August 11, 2025 at 10:59 PM
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.
July 29, 2025 at 5:33 AM
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.
Removing every component and cleaning everything didn't fix it! I'm at a loss now.
July 12, 2025 at 3:41 PM
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.
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.
Avec @downtowndougbrown.com on a réussi à trouver comment l'Easter Egg de Maula Abdul fonctionne ! www.journaldulapin.com/2025/07/08/p... www.youtube.com/watch?v=caU3...
L'Easter Egg « Paula Abdul » du Power Mac 8100 - Le journal du lapin
Le journal du lapin, mon espace personnel ou je parle de trucs retro, d'expérimentations et de produits Apple. Et évidemment de prototypes.
www.journaldulapin.com
July 8, 2025 at 9:00 PM
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.
The rubber bumper will go bad eventually, but I'm pleasantly surprised.
July 7, 2025 at 7:42 PM
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.
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!
July 6, 2025 at 9:09 PM
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!
Reposted by Doug Brown
Un autre Easter Egg découvert dans un Power Mac, avec Paula Abdul www.journaldulapin.com/2025/07/01/e...
July 2, 2025 at 10:25 AM
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!
July 1, 2025 at 5:10 AM
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".
"secret ROM image."
vs.
"secret ROM image".
June 29, 2025 at 11:52 PM
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".
"secret ROM image."
vs.
"secret ROM image".
Reposted by Doug Brown
Reposted by Doug Brown
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 […]
Original post on infosec.exchange
infosec.exchange
June 22, 2025 at 10:04 PM
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!
@dandu.be had already found the JPEG image in the ROM in 2014, but now we know how to reveal it!
June 22, 2025 at 10:20 PM
When the green light is red, it's charging. When the green light is green, it's finished.
June 4, 2025 at 7:45 PM
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”
June 3, 2025 at 5:00 AM
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?
June 1, 2025 at 5:47 PM
Oh wow, I forgot I still had this. Unopened Color StyleWriter Pro black ink cartridge. Wonder if it’s all dried up?