Jonathan Engdahl's Stuff


Lock Free



Info on building Qbus-based PDP-11's that will run Ancient UNIX, including 2.11BSD. I have not done much with the PDP-11's for several years. Some of my PDP-11 information is obsolete, such as descriptions of software for simulating and interfacing PCs to PDP-11, links to other websites, and hardware sources.

ARM Linux, I had Familiar Linux running on my iPAQ 3955., for NSLU2. For a while I was working with I Debian for the IXP4xx.

Lock Free Data Structures

I have been studying and implementing lock free data structures for bare metal real time systems on running on multi-core ARM processors. These will shortly be open sourced.

Midi Player

PlayMidiCE -- a MIDI player for Windows CE, using a Roland SCP-55 PCMCIA Sound Canvas. This stuff is really old, and there may be broken links, but it may be interesting to someone so I'll leave it up.


A tribute to my father: Roy Engdahl (oops -- dead link).

Old Engdahl Genealogy page which I have not been keeping up to date. In early 2005 I uploaded a more up-to-date version of the Corwin side to RootsWeb.

I did extensive research in 2005-2006 which greatly improved the quality of my family database. From this I prepared a paper for the Engdahl Family Reunion in July 2006 which traces the Engdahl/Phillips side of the family back to early colonial Connecticut around 1650. Here is the current paper on the Engdahl Family Tree, updated July 16, 2006. (3.9 megabytes, in PDF format).

Here is a paper on the Corwin Family Tree. This is a snapshot of a work in progress, but even in its unfinished state it contains a lot of information. This is a large PDF document (3.5 megabytes).

I zipped the PDF files to save space (this website has a 10 meg limit).  You will need Acrobat Reader to read the PDF files.


Around 2006 I created the Churchhopper's Guide to the Galaxy -- an index of churches (which actually only covers Geauga County, Ohio). This is a by-product of my research while church-hunting during September and October of 2005.

The end result of our church hunting was our current involvement in Orwell Bible Church, a church planting project in Orwell, Ohio, about 25 minutes east of where we live in Chardon. We meet in an old school building in Windsor, OH, and are currently averaging just over 40 people every Sunday morning.

What's new:

bullet5/26/2001: software, added description and upload for VTserver, including port to Windows platforms.
bullet5/26/2001: parts, found H9281 4-slot dual-wide Qbus card cage listed for $9.
bullet5/26/2001: 11/53, progress update
bullet8/2/2001: 11/53, more info, including how to burn and install ROMs. Software: added telnet interface to simh.
bullet9/10/2001: Software: uploaded 2.9BSD UNIX for 11/23 and MSCP hard drive to the PUPS archive.
bullet1/1/2002: reorg; added info on RQDX3, XXDP, and ZRQCH0.
bullet1/19/2002: added a page for vtc, under VTserver
bullet3/13/2002: added some 11/23 info; minor updates and clean-up to several other pages.
bullet2/22/2003: updates.
bullet5/25/2003: added the beginnings of the11/83 page.
bullet12/25/2005: performed trivial maintenance (mainly link rot repair). I have not been doing much with the PDP-11's the last couple years. I've been distracted by Familiar Linux and NLSU2 Linux. I have Linux running on an iPAQ 3955, was able to get gcc etc. running natively on the iPAQ, and was able to build a working Linux kernel natively.
bullet11/25/2006: I have Debian Linux 2.6.18 running on an Intel IXP465 board (a Rockwell Automation 1756-EN2T). I have gcc etc. running natively on this platform, and have been able to build the kernel and some other apps natively. The PDP-11's continue to be neglected.
bullet12/31/2009: General overhaul and facelift of the website, fix broken links, and delete promises that I will do anything with the PDP-11s anytime soon. Latest distractions are the Luminary Micro one-chip ARM Cortex-M3, which I used to build a computerized trolling motor for the sailboat, and the ARM Cortex-A9 MPCore. Added under-construction page for open source lock free data structures for the A9.


Email address:

"The things which are seen are temporary,
but the things which are not seen are eternal."
                                        II Corinthians 4:18


Last modified: December 31, 2009