One of the rarest ThinkPads is the ThinkPad PowerSeries 820, running a Power PC 603e at 100 MHz.
It’s code name is Wiltwick, the type designator (used in Windows) is 6040.
It uses an 800x600 TFT, WD90C24A/G10 graphics and has a 1.2 GB SCSI HDD.
48 MiB RAM is the maximum configuration.

This machine runs Debian 3.0 (with Linux 2.4) and Windows NT 4.0 currently.

PPC ThinkPads require an MBR partition layout with a partition of the type 0x41 (PReP boot) and the boot-flag set. This partition must directly contain the data, like an OS kernel or bootloader. The partition can be present on the hard drive, a CD ROM or even a floppy disk. External SCSI CD drives can be used, but need to support 512-byte sectors.

Running Linux

Installing Linux on PPC ThinkPads is not an easy task and needs a bit of work. There is no framebuffer support, so no graphical output or console logging will be visible. You’ll need a RS232 null-modem cable to connect to the laptop.
Serial port parameters: 9600 baud, 8 data bits, 1 stop bit, no parity.

The cd images for Debian (3.0, 3.1 and 4.0) all crash at the SCSI initialization after boot.
Propritary SuSE Linux 7.1 PPC has an install CD with a working kernel with intact SCSI. This can be used (with proper kernel command line parameters) to start the Debian setup wizard and get a basic system working.

The latest kernel we had up-and-running was 2.4.18. PCMCIA ethernet is working with an IBM Ethernet II adapter. OSS sound works stuttery with: options snd-cs4231 snd_index=0 snd_port=0x830 snd_dma2=6 snd_irq=10

More info, pre-built kernels and modules can be found at: https://github.com/Manawyrm/Thinkpad820

Running Windows NT 4.0

To install Windows NT 4.0 you’ll need to boot with a “ARC”-floppy.
The newest known version is 1.51 and can be found as a floppy image online.
Not all multi-platform CD images work on the PowerPC platform.
Known to work is Windows NT 4.0 SP1 EN (NTWKS40A/MD5:2198e2ba5cecaa1927dc242186edf344)

Tips and Tricks

• Skip anything with yaboot, it’s not compatible with these machines as you have no OpenFirmware.
• fdisk filename.iso / hit “p”, can be used to check if an .iso or .ima will be bootable on the device.
  Only 0x41 partitions can be booted.
• Boot menu is accessed with the F1 key at the boot logo
• “eatabug” typed into the boot menu opens up a firmware shell.
  Be careful! There are no security checks, especially commands like fdisk just format the drive without any confirmation!