I’m moving this content to Blogger.com, using http://jaoswald.blogspot.com/.
Why? Partly because I work for Google now, and ought to eat more of our dogfood. Partly because I can use AdSense and Google Analytics to see how folks (including spammers) can use these tools to track search traffic.
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 “PDP-10 chaosnet interface definitions”
CH11.defs1 “CH11 Unibus chaosnet interface definitions”
CHSDEF.15 “Chaos net packet definition (for PDP-10s)”
CHAOS.288
KSNET.1 “Chaosnet interface on Unibus” (presumably for the KS10)
IOELEV.432 “i/o eleven”
NET.32 General ITS networking code
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.
After trying for a while to install Linux on my old Palm Tungsten E and failing, because of hardware issues (perhaps explaining why I replaced it with an E2 way back, although my memory is dim on that), I bought an LN2410SBC from LittleChips.com.
Thanks to François-René Rideau (fare) for organizing last night’s inaugural Monthly Boston Lisp Meeting (Note: future meetings will apparently happen on the fourth Monday of the month.)
I’m surprised I haven’t seen reports on Planet Lisp yet, but I had an enjoyable time. I certainly didn’t meet everyone there, but did get to meet nyef (who showed off some of his fearless adventuring into bare-metal Lisp) and Brad Parker, got to see Kent Pitman in person, and a few other notables, as well as numerous ITA Lispers. Discussion was wide-ranging (I heard only a fraction of the multiple conversations going on), and some of the most interesting stuff to me was discussion about the background of Dylan and Lispers at Apple in the 1990s.
There was at least one person taking pictures; I’m sure they’ll pop up somewhere in the blogosphere.
Looking forward to more great meetings in the future!
Even though it is hardly a finished product, I’ve posted a snapshot of my current CL conversion of COMFY-6502 Not that I expect a huge pent-up demand for the code, but it might be slightly more interesting than the output examples. Thanks to Henry Baker for allowing the release.
The page also contains a link to the TODO file describing my next steps. (Most immediately, my attempt to include JMP elision was messy enough to convince me I need a different class to represent opcodes+arguments as a unit.)
After all the work to write a post showing off COMFY-6502’s ability to reproduce the Red Book tone routine, I made a slight mistake in translation. The code I presented differed ever-so-slightly from the Red Book routine in the case where the Y-register reached zero.
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As I’ve mentioned before, I’ve become intrigued by Baker’s COMFY assembler, and have been working on porting it to Common Lisp, and making it a bit more powerful in the link stage.
One metric to judge the success of this kind of “medium-level” language is how well it compiles compared to hand-written assembler code. For the 6502, there are a few examples of code created by wizards like Steve Wozniak, which you can find copies of around the web, the largest being the Apple II monitor, the Integer Basic interpreter, and some medium-sized ones like the Apple II 6502 step/trace, the mini-assembler, the floating-point “Wozpack,” and the Sweet-16 virtual machine.
This kind of code has a lot of quirks that make it hard to straight-forwardly translate: lots of shared “tail code”, branches known by the programmer to always be taken (to save a precious extra byte consumed by an unconditional JMP), and the classic “fake RTS trick”, pushing a return address picked from a table onto the stack, then using an RTS instead of a zero-page indirect JMP. Common in Woz’s code is a further shortening of the code by arranging the destination addresses to all be in the same 256-byte page, so the high-order byte is a constant. Some of these ideas will likely be possible with intelligent macros, combined with address labels and computation on those labels. I’m puzzling a bit over how to optimize the “same page” condition: whether to include a “link-time assert”, which will issue an error if the code is emitted so as to cross a page, or an even more intelligent “link-time computation” which, given the current available memory space, can choose a location that meets the constraints.
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