Despite the allure, a highly compressed OS X Live DVD built with TransMac and the "81 fixed" is an exercise in frustration. Real-world constraints include:
In online forums (InsanelyMac, Reddit, or obscure GitHub Gists), "81 fixed" likely refers to a patched version of a bootloader file (perhaps boot.efi version 81 or a modified TransMac.exe build 81) or a specific DD command that corrects byte 81 in the boot sector. Alternatively, it could denote the -no_compat_check flag applied to OS X 10.8 Mountain Lion (build 12A81) to bypass compatibility checks.
A more technical interpretation: When creating a compressed live DVD, the boot process fails with an error code 0x81—"device not configured." The "fixed" implies a patch to the IOStorageFamily.kext or a custom com.apple.Boot.plist that includes: mac os x live dvd highly compressed dvd transmac 81 fixed
<key>Kernel Flags</key>
<string>rd=udf wait=60 -v</string>
This extends the timeout for the optical drive to spin up and decompress the root image. Without this fix, the bootloader attempts to mount the compressed DMG before the DVD drive is ready, leading to an infinite reboot cycle.
The appeal of a highly compressed OS X Live DVD is obvious: portability, forensics, and legacy system repair. Imagine inserting a single 4.7GB DVD into an old Mac (or a Hackintosh) and booting directly into a fully functional Snow Leopard or Lion environment without touching the internal hard drive. To fit a 6–8 GB base system onto a DVD, one must employ aggressive compression (e.g., using hdiutil with UDZO or UDBZ formats) and strip away non-essential components—languages, printer drivers, and even the graphical installer. Despite the allure, a highly compressed OS X
However, macOS’s kernel and boot process (boot.efi, mach_kernel, and the BootX bootloader) expect a writable root filesystem. Mandating that the entire OS runs from a read-only compressed image requires extensive modifications to the boot arguments (rd=udf, -s for single-user mode) and initramfs-like structures. Most attempts fail at the "Still waiting for root device" error—a direct result of the optical drive’s latency and the system’s inability to mount the compressed DMG in time.
Use TransMac or BalenaEtcher to write the same compressed DMG to an 8GB USB stick. Most Macs (2006-2019) can boot from USB (hold Option key). No DVD needed. This extends the timeout for the optical drive
Short answer: Yes, but with major caveats.
Let's break down the user's intent behind each term.