Brasstacks

Heathkit Jr Electronic Workshop "35", Model JK-18 The Heathkit Jr 35 evidently had been stored with batteries in the battery holder, which corroded badly. I replaced it with a plastic RadioShack 4 D-cell battery holder (270-389), wired into the negative power rail and the hot side of the power switch (which is part of the variable resistor). Corroded battery holder Replacement battery holder mounted I mounted the replacement battery holder with a dozen "heavy duty" 1 inch foam double-stick mounting squares (rated to hold 900g), stacked in four groups each three high to overcome the various screws protruding through the main board. The remote speaker station The rubber foot used to protect the relay from being crushed when you turn the kit over was stuck to the remote speaker station. I put it in its rightful place. Relay with the brown rubber foot Earlier, I had built a couple simple circuits, which showed the meter and new battery pack w...

I just picked up a Heathkit Jr. "35" circuit experimenter kit on eBay. I had one of these as a child; I don't remember how it is that we came to own it, but I had an itch to re-read the manual. Buying the manual from vintagemanuals.com would have cost as much as the kit + manual. I remember being befuddled by the descriptions of how transistors worked. It turns out the descriptions of capacitors and transistors were a bit sketchy: I think it is pretty much impossible to understand how the AM radio experiments actually function from the text. The operation of the ferrite-core antenna and the various windings are unexplained as well. I was a bit surprised to find all four transistors in the kit are identical. Thanks to this Heathkit part cross-reference , I see that they are part 417-118, a.k.a. 2N3393 NPN transistors.

I'm working on importing my blog from Wordpress.com . Blogger.com apparently will let me use AdSense even with free hosting, and I should get to know more about AdSense and about the Blogger platform as well, as a Googler. I used the Wordpress.com export feature to create an XML file, and used the http://wordpress2blogger.appspot.com/ tool to convert it, as I was under the 1 MB size limit. The code behind that converter is evidently at  http://code.google.com/p/google-blog-converters-appengine/ . That tool plus Safari saved the result with an .xml.html extension, which resulted in a Blogger error code of "bX-uroqxm" when importing. Removing the extraneous .html allowed the Blogger import to mostly succeed. It does not re-map my Wordpress author identity to my Blogger profile. It also does a pretty poor job importing my source-code formatted content. So I'll be slowly publishing the old posts, tweaking that kind of thing as I go.

This is not particularly interesting, but I wanted to record a couple of links to ChaosNET code for the PDP-10. The ChaosNET memo describes an ITS (Incompatible Time-Sharing System) interface, for which the code is somewhere in the ITS sources, and a Lisp Machine implementation, for which code is in the CADR sources and Symbolics code base, but also a TOPS-20/TENEX implementation, a VMS/VAX implementation, and a UNIX implementation. The UNIX implementation was documented by James E. Kulp for Symbolics, and the code seems to have survived. The TOPS-20/TENEX is harder to find, but it looks like BitSavers' Foonly archives have some files. DSK:<FOONEX>CHAOS.MAC;399 DSK:<FOONEX>CHABUG.MAC;8 DSK:<FOONEX>CHAOS0.MAC;3 DSK:<FOONEX>CHATTY.MAC;21 I have no idea whether this is at all related to the implementation the AI MEMO mentions. A Google search turns up some interesting code (might be for the PDP-11 front end, for ITS) from AI:SYSTEM CH10.defs1 ...

Hans Hübner has been at it again, and has developed code to allow a  Teensy AVR development board to adapt a Symbolics keyboard to USB . I ordered a Teensy board of my own, and was hoping to develop a small adapter to avoid cutting up my keyboard cable, but Teensy does not work with my old Mac OS X 10.4 system.

I wanted to post a link referring to recent progress on adapting Symbolics keyboards to modern PCs. Hans Hübner announced that the kbdbabel project (apparently based on 8051 microcontrollers) was able to be adapted to support the slim-line (Rev. C) Symbolics keyboard, adapting it to PS/2 protocol . My own work in this area ground to a halt pretty soon after I received the ADB adapter from DKS. I'm happy to see that others have been able to make progress! UPDATE: Rainer Joswig has commented on his experience using the kbdbabel adapter to connect a Symbolics keyboard to a Macbook running Mac OS X . UPDATE 2: Hans has developed a USB adapter solution .

Mostly to support my own development on multiple computers, I've moved my Common Lisp port of COMFY-6502 to github. I chose the name cl-comfy-6502 for the repository, although the "cl" prefix is a bit ugly. The current snapshot of COMFY-6502 .