Webtagr - Technology News Summarizer

Resurrecting a Lost Piece of Apple History: The Performa 550's Secret Recovery Partition

2025-03-16

While rescuing data from a failing hard drive in an old Apple Performa 550, the author uncovered a hidden recovery partition containing a fascinating piece of Apple's software history. This partition, designed to boot in case of system failure, allowed users to reinstall the OS. A three-year quest involving online appeals culminated in finding a pristine hard drive, revealing the partition's mechanics and leading to the sharing of its image. This compelling story highlights the thrill of tech archeology and software preservation.

(www.downtowndougbrown.com)

Tech tech archeology hard drive recovery

Resurrecting 30-Year-Old Apple SCSI Hard Drives: The Rubber-Decay Data Recovery

2025-03-02

This post details the author's experience restoring 1990s Apple-branded Quantum and Conner SCSI hard drives. These drives commonly suffer from a failure mode where they spin up and immediately stop. By opening the drives, the author discovered the root cause: aging rubber bumpers causing the read/write head to stick. Two methods—manually moving the head and using Kapton tape to hold it in place—were successfully employed to recover data. The article also shares interesting details about how data is physically stored on these drives and serves as a reminder to regularly back up important data.

(www.downtowndougbrown.com)

Hardware vintage hardware SCSI hard drive

The Undocumented 68030 Instruction That Saved the Mac Classic II

2025-01-25

While debugging a Macintosh Classic II in MAME, the author discovered a bus error causing a 'Sad Mac' in 32-bit addressing mode. Reverse engineering revealed an out-of-bounds jump in the ROM, leading the CPU to execute an undocumented 68030 instruction. Surprisingly, this instruction corrected the value of register A1, preventing a crash and allowing the Classic II to boot successfully. The author validated this by repairing a vintage Classic II and modifying its ROM. This case highlights the power of emulators in uncovering hardware quirks and showcases how a software bug was inadvertently fixed by hardware.

(www.downtowndougbrown.com)

Hardware

Chumby 8 Kernel Upgrade: Solving the 100% CPU Usage Mystery

2025-01-13

While upgrading the Linux kernel of his Chumby 8 device to version 6.x, the author encountered a persistent 100% CPU usage problem. Through time-reversal debugging, kernel profiling, and a deep dive into the `/proc/stat` file, the root cause was traced to a timing issue in the kernel code that reads the PXA168 hardware timer register, resulting in inaccurate idle time counting. The author fixed this problem and contributed the solution back to the main Linux kernel.

(www.downtowndougbrown.com)

Development Hardware Debugging