Archive for October 28, 2019

Monday, October 28, 2019

Enabling Defragmentation on APFS Hard Drives

Howard Oakley:

You can try this yourself, although the documentation of defragmentation is minimal. The diskutil apfs command allows you to enable and disable defragmentation at Container or Volume level, with a command such as diskutil apfs defragment volumeDevice enable enabling it on the specified volume. But I wouldn’t expect it to have any significant impact on the poor performance that you’re experiencing on APFS-formatted hard drives. I hate to say it, but if you possibly can, it would make good sense to keep those in HFS+ format until you replace them with SSDs.


Update (2023-08-31): Felix Schwarz:

Three days ago, I noticed an external HDD’s write performance had deteriorated to about 2-5 MB/s, making me wonder if it was about to fail - or if it is an APFS performance issue.

I subsequently learned about APFS defragmentation and enabled it for the HDD’s APFS container via

diskutil apfs defragment [disk] enable

Coming back to the disk two days later, write performance is back to normal.

How to Mirror Selected Screens

Adam Engst:

The problem was that Sal could only see the MacBook Pro and the iPad on the podium. For anything that happened on the projector, he had to peer into the distance to work from the projected screen. That proved difficult, but he soldiered through the presentation.

Afterward, Ed Marczak, a speaker and advisor to MacTech Conference who wasn’t in the room during the setup time, shared a little-known tip that would have made things easier on Sal. It turns out that if you have three (or more) screens connected to a Mac, you can mirror two of the three by Option-clicking one and dragging it on top of another. This does exactly what you’d expect. The Mac acts as though it has only two screens instead of three, and the same image appears on the two that are mirrored, with the third being separate.

Retroactive to Run Aperture, iPhoto, and iTunes

Tyshawn Cormier:

After updating to macOS Catalina, Aperture and iPhoto no longer runs, and iTunes is replaced by Music, TV, and Podcasts. If you still need to run Aperture, iPhoto or iTunes on macOS Catalina, the Retroactive app makes it easy.


Retroactive will install or modify the app you chose. Modifying Aperture and iPhoto to run on macOS Catalina should only take about 2 minutes.


All Aperture features should be available except for playing videos and exporting slideshows.

Those require 32-bit components. Running Aperture this way is probably a little risky since it was never designed to work on Catalina. On the other hand, it may be a good option since there are issues getting Aperture to work in a virtual machine.

Here’s more about how Retroactive works:

It’s no news that the brave and the reckless have been able to monkey-patch and shoehorn macOS into running system apps under completely unsupported configurations. A rundown of the brave heroes.


To proceed, we need to get NyxAudioAnalysis.framework from macOS Mojave. Because I upgraded from macOS Mojave to macOS Catalina, I don’t have that framework file anymore.


The stack trace is fascinating. It looks like some sort of access violation when initializing a font. We are going to fix this by swizzling Aperture.


The Team Behind the 6502

Team 6502 (via Hacker News):

When it was introduced in 1975 by MOS Technology of Valley Forge, Pennsylvania, the 8-bit microprocessor sold for a fraction of the cost of other microprocessors, causing rapid decreases across the entire computing industry. Featured in such seminal products as the Apple I and II, the Commodore PET, and the BBC Micro, as well as Atari and Nintendo game consoles, the 6502 microprocessor has been the brains inside toys, office machines, and medical devices too numerous to mention. As one of the most widely used microprocessor architectures of all time, the CMOS related form of the 65XX developed by the Western Design Center is still in production today, with an estimated six billion units so far produced.

While the story of Chuck Peddle, the visionary who conceived of the 6502, and that of design team member and founder of the Western Design Center, Bill Mensch, are widely recognized and recorded, the stories of the other MOS Technology engineers and employees who also worked on the 6502 and their contributions are not. This website seeks to change that.

Harry Bawcom:

In the 1970s much of what today is done by computer had to be done by hand. In the case of the 6502, once the design of the chip was completed by the team that worked on the chip’s architecture, that schematic was given to the design layout team. It was our job to create a topological layout from that schematic, a layout of all the transistors which made up the 11 or so glass reticles, also called "masks" that were then used to create the chip.


Design rule checking (the physical spacing between metal stripes: too close together and they will always short out in manufacture, making the chip non functional) and verifying schematic to layout was all manual. It was done by coloring a plot with colored pencils again and again as coloring a plot guided your eye to notice incorrect spacings or design rule violations.

Sydney Anne Holt:

We were given the logic drawings from Bill Mensch and Ray Hirt and etc, and turned them into the drawing you see in the picture from the Electrical Engineering Times article from 1975.

To do this, we drew them in pieces on big sheets of mylar that fit together like a puzzle. In order to do a careful logic to layout check we taped all the pieces together on the floor and crawled around on it to trace out the lines. The drawings were then digitized into layers so masks could be made from them.

I remember that once, one of the guys took off his shoes and was on the mylar checking when it was discovered his socks were damp and his toes were erasing the drawing as he moved along. Fortunately, it was caught very soon so the rework was minimal.