Landon Curt Noll
11dfe51c6c
Created `quick-start.md` to hold the FAQ 0.0 content. Used `sgit(1)` to change: * faq.html#enter ==> quick-start.html#enter * faq.html#enter_questions ==> quick-start.html#enter_questions * faq.html#step_0 ==> quick-start.html#step_0 * faq.html#step_1 ==> quick-start.html#step_1 * faq.html#step_2 ==> quick-start.html#step_2 * faq.html#register ==> quick-start.html#register * faq.html#step_3 ==> quick-start.html#step_3 * faq.html#step_4 ==> quick-start.html#step_4 * faq.html#step_5 ==> quick-start.html#step_5 * faq.html#step_6 ==> quick-start.html#step_6 * faq.html#step_7 ==> quick-start.html#step_7 * faq.html#step_submit ==> quick-start.html#step_submit Via: ```sh sgit -e 's/faq\.html#enter/quick-start.html#enter/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#enter_questions/quick-start.html#enter_questions/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_0/quick-start.html#step_0/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_1/quick-start.html#step_1/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_2/quick-start.html#step_2/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#register/quick-start.html#register/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_3/quick-start.html#step_3/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_4/quick-start.html#step_4/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_5/quick-start.html#step_5/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_6/quick-start.html#step_6/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_7/quick-start.html#step_7/g' '*.md' '*.hdr' 'inc/*.html' sgit -e 's/faq\.html#step_submit/quick-start.html#step_submit/g' '*.md' '*.hdr' 'inc/*.html' ``` The former FAQ 0.0 section in `faq.html` now just refers to `quick-start.html`. Modified menu and non-JS menu so that "Enter the IOCCC" refers to `quick-start.html`. Changed `bin/gen-top-html.sh` VERSION from "1.4.10 2024-11-23" to "1.4.11 2025-01-09". Performed `make www` on macOS to complete the above.
To build:
make
NOTE: this entry requires the X11/Xlib.h header file and the X11 library to
compile. For more information see the
FAQ on "X11".
To use:
./grothe carrier_freq pixelclock horizontal_total < some_input.txt
Try:
Put on your "electronic ears" and then try:
./try.sh
You may find using a tunable scanning electronic ear helps.
Judges' remarks:
Most of the time, interference is annoying. This entry is the exception that proves the rule. What is a bug to some is a feature to this entry. :-)
Author's remarks:
The program draws patterns on the screen that can be picked up by a
shortwave radio. It emulates
the frequencies for an old fashion touch tone phone, so old songs can be played
by hitting 0-9,#, and *.
To be able to run the program you need to determine the following parameters:
-
carrier_freq- base frequency used to host music
-
pixelclock- refresh rate of the monitor
-
horizontal_total- total scan along the horizontal axis
If you have xvidtune installed you can get the pixelclock and
horizontal_total with the following command
xvidtune -show | head -n 1 | awk '{ print "pixelclock " $2 * 1000000 " horizontal_total = " $6 }'
Example from my laptops:
./grothe 65000000 10000000 1344 < twinkle.txt
Even if the user gets a setting off, the sound will usually be able to be heard on AM at a multiple of the original frequency.
The core idea of using a machine to play music on AM radio goes all the way back to the Altair computers and Timex Sinclair ZX-81s.
Several example songs
Olympics Fanfare - from antang@phakt.usc.edu - Tony:
4-9-91231,2222-321123123-9-91231,2222-32112321
Twinkle Twinkle Little Star - from fsufunkyb@aol.com - Ben Schmidt:
1199##9-6633221-9966332-9966332-1199#9-6633221-
Generic Arabian Tune - from rdippold@qualcomm.com - Ron "Asbestos" Dippold:
453,54,4569564459,9#95458,8987453 54
Others can be found by doing a search for "touch tone phone songs".
Obfuscations
- Some numbers expressed in Octal, some in hex and some in decimal:
"A foolish consistency is the hobgoblin of little minds." - Ralph Waldo Emerson.
- Funky scoping, looking at the nanosleep section and
XsetWindowAttributesdeclares local variables. - Algorithm is very weird, uses
ydimension to draw carrier frequency andxdimension to draw audio frequency, based on Erik Thiele's Tempest for Eliza. - lack of
#defines confuses many people :-) - figuring out your
pixelclockandhorizontal_totaland whichcarrier_freqto use can be an exercise in obfuscation for the user. - use of commas in various places, confuses most C code beautifiers sometimes making the beautified code harder to read
- use of
staticto ensure initialization is EVIL and done in several places - uses
staticdeclarations &voidfunction returns we don't care about making the code harder to read. - does sound using only X11 libs, no other libs required.
- demonstrates tempest emissions in a fun/easy way.
- follows good programming practices of actually setting exit codes and giving usage when run with incorrect parameters.
References
Tempest for Eliza - Basis for Algorithms.
Tempest
AM
- Another early program in this field. See
here
for a bit more information on the program (search for Tempest-AM Radio Signal Transmitter).
The paper Soft Tempest: Hidden Data Transmission Using Electromagnetic Emanations by Markus G. Kuhn's and Ross J. Anderson's.