What’s inside Apple’s $129 Thunderbolt cable? We CT scanned one to find out, and compared it to some cheaper cables… 🧵

@lumafield Computer media week continues here!

MO lost its advantage first as CD-RW technology became cheap and reliable, and was fully wiped out by the emergence of portable solid-state storage like USB thumb drives. RIP 🪦. You can explore this scan of a MO disc here! (Plus other bygone media).

MO discs had a multilayer structure: plastic substrate, reflective layer, magneto-optical layer, and protective coating. This made them more durable than magnetic storage—resistant to scratches, environmental wear, and bit rot.

For reading, a low-power laser scans the disc. The polarization of the reflected light shifts depending on the magnetic orientation of the recorded bit—the magneto-optic Kerr effect. It’s precise, though relatively slow compared to later optical media.

Continuing our @lumafield CT scans of computer media with magneto-optical discs! These blend magnetic writing and optical reading. A laser heats a tiny region of the disc to its Curie point and a magnetic field sets the data. MO discs were used until CD-RW caught up.

@lumafield Here's the Wednesday installment, featuring @lumafield scans of an Atari ROM cartridge!

If you enjoyed these CT scans of floppy disks, check out today's installment, featuring a @lumafield scan of an Atari ROM cartridge:

@lumafield And here are some scans of floppy disks:

@lumafield We're posting @lumafield CT scans of computer media all week. Here's the first installment, on tape storage:

You can explore this @lumafield scan of an Atari 2600 cartridge right here! Come back tomorrow to see a scan of a magneto-optical disk, and on Friday to see scans of hard drives.

Sometimes cartridges didn’t boot, and the popular fix was to blow on the contacts. This didn’t help much; it was usually the act of re-seating the cartridge that resolved the issue. Blowing on the contacts could introduce foreign debris and cause the contacts to corrode.

These cartridges were designed to require very little insertion force in order to reduce wear and make them easy to use. This particular cartridge doesn’t have any snap-fit features in the plastic housing; instead its walls are drafted inward so that it fits snugly into the

The memory module uses an edge connector. Each of the contact pads here lines up with a spring-loaded contact in the cartridge slot. It’s a very simple, flexible, and inexpensive connector design.

Behind the memory module, a big spring stands out. It keeps a trapdoor closed across the cartridge’s opening.

Compare the simplicity and empty space here to a modern connector like Thunderbolt!.

Cartridges housed PCBs in rugged plastic shells, typically ABS or polycarbonate. There's lots of empty space here; the enclosure was designed to contain additional components as needed. The Zelda NES cartridge had a battery inside to support game saves!

ROM stands for Read-Only Memory. These chips were pre-programmed with data that could be read by the device but not altered. In most cartridges, the data was stored in masked ROM—permanently etched into the silicon during manufacturing.

This is an X-ray CT scan of an Atari 2600 ROM cartridge. In addition to early gaming consoles, this storage format was also used with computers, instruments, and calculators. Let's look inside, and find out why blowing into the connector didn't really help. 🧵

@lumafield Check out chapter 2 here, looking at floppy and ZIP disks!

Floppy tech faded fast after USB drives arrived. We'll talk about those later this week; in the meantime, you can explore our CT scans of ZIP disks here! Come back tomorrow for scans of ROM cartridges—and learn why blowing into them didn't actually help.