Dual-boot NT and NetBSD on the Libretto 70CT


The tiny Libretto 70CT is one of my all-time favourite computers. I bought one on eBay a decade ago to fulfil a childhood dream, and it’s been so much fun to use. It packs a Pentium 1 CPU, 32 MiB of memory, and a 640x480 VGA display into a tiny case that even by today’s standards is impressive. I’ve blogged about it a few times.

Last weekend’s project was getting it dual-booting with Windows NT 4.0 for nostalgia and because it has drivers, and NetBSD 8.1 because I can. For those asking why, why do people do anything?

You’ve got a few options for dual booting. This NetBSD mailing list thread suggested WinImage BootPart which can add NetBSD to Windows NT’s boot loader, but I decided just to use NetBSD’s.

Getting it dual booting was easier than I expected.

Preparing the boot volume

  1. Attach your boot device to an external machine with a hypervisor. Use a 16 GiB CompactFlash card with a 2.5-inch IDE adaptor if you can, it’ll be faster and use less power than spinning rust.

  2. Pass the boot device into the hypervisor. I use bhyve, but any Unix-like machine can use QEMU to do this easily too.

Installing Windows NT

  1. Boot Windows NT 4.0 from ISO, if you can avoid creating those boot floppies. If the installer detects your VM as an MPS Multiprocessor PC as it does under bhyve, change it to Standard PC or it won’t boot.

  2. Partition your drive with sufficient leftover space for NetBSD. I tend to create a 2 GiB NTFS partition, and a 128 MiB FAT32 for sharing data with NetBSD.

  3. After that point, it’s a standard install. Let it finish, and restart a couple of times. Copy the drivers from the Toshiba Dynabook website, but don’t install until it’s in the Libretto.

Installing NetBSD

  1. Boot the NetBSD 8.1 installer from ISO. At the MBR step, choose Edit the MBR partition table insead of Use the entire disk.

  2. At the MBR table editor step, edit the first partition and set its bootmenu to something like NT4. Then add your NetBSD install to partiton B. Set Active to Yes, Install to Yes, and bootmenu to something like NetBSD.

  3. The rest of the install is standard. I echewed (gesunteit) X11 for now, because I want to see how much I can get away with using curses-style applications! But I’ll definitely be trying IceVM and Fluxbox on it at some point.

  4. Reboot, and you should get NetBSD’s minimal boot loader.

Finishing up

Pop the drive out, put in the Libretto, and you should have your obscurely fabulous Libretto booting what you want.

Booting from Hard Disk...
Fn: diskn
1: NT4
2: NetBSD

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Ruben Schade is a technical writer and infrastructure architect in Sydney, Australia who refers to himself in the third person. Hi!

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