10 files changed, 614 insertions, 0 deletions
diff --git a/src/abgabe.org b/src/abgabe.org
new file mode 100644
index 0000000..772d04d
--- /dev/null
+++ b/src/abgabe.org
@@ -0,0 +1,101 @@
+#+TITLE: Übungsblatt 5 - Aufgabe 3
+#+HTML_HEAD_EXTRA: <meta name="robots" content="noindex">
+#+SETUPFILE: ../options.org
+
+[[https://thomaslabs.org/shortcoil.m][Quellcode herunterladen]]
+
+* Ergebnisse des Programms
+[[https://thomaslabs.org/media/betrag.png]]
+
+[[https://thomaslabs.org/media/richtung.png]]
+
+[[https://thomaslabs.org/media/spulenachse.png]]
+* Octave / Matlab Quellcode
+#+BEGIN_SRC octave
+  clear all;
+  close all;
+  clc;
+
+  %% length of the observed region in m
+  len = 40e-3; %m
+  len = len / 2; %we shall go from -len to +len
+  %% number of points in x- and z-direction
+  N_space = 50;
+  %% number of points for integration along coil
+  N_phi = 250;
+  %% radius
+  R = 5e-3; %m
+  %% length
+  L = 23e-3; %m
+  %% number of windings
+  N = 5;
+  %% current
+  I = 8; %A
+  %% vacuumpermeability
+  mu0 = 4 * pi * 1e-7; %Vs/Am
+
+  %% define grid
+  z = linspace(-len, len, N_space); %m
+  x = linspace(-len, len, N_space); %m
+
+  %% parameter of coil-wire-path-paramtrisation
+  phi = linspace(0, N * 2 * pi, N_phi);
+  dphi = phi(2) - phi(1);
+
+  %% Precalculate cos and sin
+  p_sin = sin(phi);
+  p_cos = cos(phi);
+
+  %% loop through all x-z-points
+  for iz = 1 : N_space
+    for ix = 1 : N_space
+      %% r of this x-z-point
+      r = [x(ix); 0; z(iz)];
+      B = [0; 0; 0];
+
+      %% Riemann sum along the coil
+      for ip = 1 : N_phi
+        %% Point along the coil
+        l = [R * p_cos(ip); R * p_sin(ip); ip * L / N_phi - L / 2];
+        %% Vector tangent to the coil of length dl = R * dphi
+        dl = [- R * p_sin(ip); R * p_cos(ip); L / 2 / N / pi];
+        dl = (R * dphi / norm(dl)) * dl;
+        %% Vector from the coil to the x-z-point
+        rp = r - l;
+        %% Add dB
+        B = B + (mu0 / 4 / pi) * I * (1 / norm(rp) ^ 3) * cross(dl, rp);
+      end
+
+      B_X(iz, ix) = B(1);
+      B_Y(iz, ix) = B(2);
+      B_Z(iz, ix) = B(3);
+    end
+  end
+
+  figure('Name', 'Richtung der Flußdichte', 'NumberTitle', 'off');
+  quiver(x * 1e3, z * 1e3, B_X ./ sqrt(B_X .^ 2 + B_Z .^ 2),
+         B_Z ./ sqrt(B_X .^ 2 + B_Z .^ 2));
+  title('Richtung der Flußdichte')
+  xlabel('x [mm]')
+  ylabel('z [mm]')
+  axis image
+  saveas(gca, 'richtung.png')
+
+  betrag = sqrt(B_X .^ 2 + B_Y .^ 2 + B_Z .^ 2)
+  figure('Name', 'Betrag der Flußdichte', 'NumberTitle', 'off');
+  imagesc(x * 1e3, z * 1e3, betrag);
+  title('Betrag der Flußdichte');
+  xlabel('x [mm]')
+  ylabel('z [mm]')
+  colormap(gray);
+  colorbar('title', 'B [T]');
+  saveas(gca, 'betrag.png')
+
+  figure('Name', 'Flußdichte entlang Spulenachse', 'NumberTitle', 'off');
+  B_2 = B_Z(:, round((N_space - 1) / 2));
+  plot(x * 1e3, B_2);
+  title('Flußdichte entlang Spulenachse');
+  xlabel('z [mm]');
+  ylabel('Flußdichte [T]');
+  saveas(gca, 'spulenachse.png')
+#+END_SRC
diff --git a/src/index.org b/src/index.org
new file mode 100644
index 0000000..77dfc1f
--- /dev/null
+++ b/src/index.org
@@ -0,0 +1,27 @@
+#+DATE: <2021-02-26>
+#+SETUPFILE: ../options.org
+{{{date_place(Bremen, Germany)}}}
+
+/Welcome!/ I am Thomas and this is my personal website.
+
+
+/Note: This site is still under development!/
+
+The idea behind this site is to share with the world the stuff
+I do in my free time. Here you can find articles about
+hobbyist electronics, programming and maybe in the future even
+math and physics.
+
+You can contact me through my email
+@@html:<span class="link-like">@@thomas at thomaslabs dot org@@html:</span>@@.
+Here is my [[local:/pub.key][OpenPGP key]].
+
+** Donations
+If you wish to support the things I do, a donation is always welcome.
+
+- Monero ([[/xmr.png][XMR QR)]]:
+  @@html:<span style="font-size:x-small;overflow-wrap:break-word">@@
+  4A8brnoX1B9NNopzoYMvAQW1ggA6sWBckN3McRTsU3mtFFkTV71XpWJHn4JHAytdo6CEqrcmhGqx556G7Fb7HNBRUaujwwB
+  @@html:</span>@@
+
+- [[https://paypal.me/thomasalbersraviola][PayPal]]
diff --git a/src/privacy.org b/src/privacy.org
new file mode 100644
index 0000000..9e48a38
--- /dev/null
+++ b/src/privacy.org
@@ -0,0 +1,96 @@
+#+TITLE: Privacy Policy
+#+HTML_HEAD_EXTRA: <meta name="robots" content="noindex">
+#+SETUPFILE: ../options.org
+
+Personal data (usually referred to just as "data" below)
+will only be processed by us to the extent necessary and
+for the purpose of providing a functional and
+user-friendly website, including its contents, and the
+services offered there.
+
+Per Art. 4 No. 1 of Regulation (EU) 2016/679, i.e. the
+General Data Protection Regulation (hereinafter referred
+to as the "GDPR"), "processing" refers to any operation or set of
+operations such as collection, recording, organization, structuring,
+storage, adaptation, alteration, retrieval, consultation, use,
+disclosure by transmission, dissemination, or otherwise making
+available, alignment, or combination, restriction, erasure, or
+destruction performed on personal data, whether by automated means or
+not.
+
+The following privacy policy is intended to inform you in particular
+about the type, scope, purpose, duration, and legal basis for the
+processing of such data either under our own control or in conjunction
+with others. We also inform you below about the third-party components
+we use to optimize our website and improve the user experience which
+may result in said third parties also processing data they collect and
+control.
+
+Our privacy policy is structured as follows:
+
+1) Information about us as controllers of your data
+2) The rights of users and data subjects
+3) Information about the data processing
+
+* I. Information about us as controllers of your data
+The party responsible for this website (the "controller") for
+purposes of data protection law is:
+
+Thomas Albers Raviola@@html:<br>@@
+Email: tgalbers2000 /at/ google /dot/ com
+
+* II. The rights of users and data subjects
+With regard to the data processing to be described in more detail
+below, users and data subjects have the right
+
+#+ATTR_HTML: :type disc
+- to confirmation of whether data concerning them is being processed,
+  information about the data being processed, further information
+  about the nature of the data processing, and copies of the data (cf.
+  also Art. 15 GDPR);
+
+- to correct or complete incorrect or incomplete data (cf. also Art.
+  16 GDPR);
+
+- to the immediate deletion of data concerning them (cf. also Art. 17
+  DSGVO), or, alternatively, if further processing is necessary as
+  stipulated in Art. 17 Para. 3 GDPR, to restrict said processing per
+  Art. 18 GDPR;
+
+- to receive copies of the data concerning them and/or provided by
+  them and to have the same transmitted to other providers/controllers
+  (cf. also Art. 20 GDPR);
+
+- to file complaints with the supervisory authority if they believe
+  that data concerning them is being processed by the controller in
+  breach of data protection provisions (see also Art. 77 GDPR).
+
+In addition, the controller is obliged to inform all recipients to
+whom it discloses data of any such corrections, deletions, or
+restrictions placed on processing the same per Art. 16, 17 Para. 1, 18
+GDPR. However, this obligation does not apply if such notification is
+impossible or involves a disproportionate effort. Nevertheless, users
+have a right to information about these recipients.
+
+#+BEGIN_EXPORT html
+<strong>
+Likewise, under Art. 21 GDPR, users and data subjects have the right
+to object to the controller's future processing of their data pursuant
+to Art. 6 Para. 1 lit. f) GDPR. In particular, an objection to data
+processing for the purpose of direct advertising is permissible.
+</strong>
+#+END_EXPORT
+
+* III. Information about the data processing
+
+We do not store any data.
+
+#+BEGIN_EXPORT html
+<a target="_blank"
+   rel="noopener"
+   href="https://www.ratgeberrecht.eu/leistungen/muster-datenschutzerklaerung.html">
+Model Data Protection Statement</a> for
+<a target="_blank"
+   rel="noopener"
+   href="https://www.ratgeberrecht.eu/">Anwaltskanzlei Weiß &amp; Partner</a>
+#+END_EXPORT
diff --git a/src/programs/index.org b/src/programs/index.org
new file mode 100644
index 0000000..f5ac0b1
--- /dev/null
+++ b/src/programs/index.org
@@ -0,0 +1,20 @@
+#+TITLE: Programs
+#+DATE: <2021-02-26>
+#+SETUPFILE: ../../options.org
+
+{{{date_place(Bremen, Germany)}}}
+
+The purpose of this section is to serve as place to share the
+collections of programs I have written.
+
+All programs here published are under the conditions of the [[https://www.gnu.org/licenses/gpl-3.0.en.html"][GPLv3
+Licence]] unless explicitly noted and are therefore [[https://www.fsf.org/about/what-is-free-software][Free Software]].
+
+Many of these programs were created to solve particular
+problems that maybe only I had. As such I may not include
+changes to them, unless I really felt that such changes could
+improve their performance and use range. That being said, feel
+free to adapt them to your own use case.
+
+- [[https://gitlab.com/thonos/autotag][autotag]] a program designed to fill metadata into songs from within
+  the terminal (uses dmenu).
diff --git a/src/style.css b/src/style.css
new file mode 100644
index 0000000..bd731ad
--- /dev/null
+++ b/src/style.css
@@ -0,0 +1,123 @@
+html {
+    height: 100%;
+    color: #cccccc;
+    background-color: hsl(240, 30%, 10%);/*#452b41*/ /*#2c314b*/
+}
+
+body {
+    margin: auto;
+    max-width: 64em;
+    min-height: 100%;
+    display: flex;
+    flex-direction: column;
+    background-color: hsl(240, 30%, 15%);
+}
+
+nav {
+    /*#3a2438*/ /*#2a3257*/
+    background-color: hsl(240, 30%, 20%);
+}
+
+nav > ul {
+    display: flex;
+    margin: 0 auto;
+}
+
+nav > ul > li:last-child {
+    margin-left: auto;
+}
+
+nav ul {
+    padding: 0;
+}
+
+nav li {
+    margin: 2px;
+    display: block;
+    list-style: none;
+}
+
+nav li:hover {
+    background-color: hsl(240, 30%, 30%);
+}
+
+nav .submenu:hover .submenu-contents {
+    display: block;
+}
+
+nav .submenu-contents {
+    display: none;
+    position: absolute;
+    z-index: 10;
+    background-color: red;
+}
+
+nav a,
+nav span {
+    text-decoration: none;
+    color: #dddddd;
+    display: block;
+    line-height: 2em;
+    height: 2em;
+    margin-left: 1em;
+    margin-right: 1em;
+}
+
+nav span {
+    cursor: pointer;
+}
+
+.article-date {
+    margin-left: auto;
+}
+
+.link-like, a {
+    color: #eeeeee;
+    text-decoration: underline;
+}
+
+.rel-header {
+    padding: 1em 2em 1em 2em;
+}
+
+header {
+    background-color: hsl(240, 30%, 10%);
+}
+
+header p {
+    text-align: center;
+    margin-bottom: 0.15em;
+}
+
+header p ~ h1 {
+    margin-top: 0.15em;
+}
+
+main {
+    padding: 2em 2em 2em 2em;
+    flex-grow: 1;
+}
+
+hr {
+    margin: 0;
+    margin-top: auto;
+}
+
+footer {
+    padding: 1em 2em 1em 2em;
+}
+
+figure {
+    text-align: center;
+}
+
+figure img {
+    max-width: 30em;
+    object-fit: contain;
+    display: block;
+    margin: auto;
+}
+
+h1, h2, h3, h4, h5, h6 {
+    text-align: center;
+}
diff --git a/src/z80/index.org b/src/z80/index.org
new file mode 100644
index 0000000..ab827eb
--- /dev/null
+++ b/src/z80/index.org
@@ -0,0 +1,22 @@
+#+TITLE: Z80
+#+DATE: <2021-03-03>
+#+SETUPFILE: ../../options.org
+
+{{{date_place(Bremen, Germany)}}}
+
+This section is dedicated sharing all the Z80 related work. This
+includes software, schematics and tools that I've designed to
+accomplish this task. It also includes a kind of narration of the
+project itself, throughout its development and changes.
+
+** Articles about the history of the project
+- [[local:/z80/plm.html][PLM: Pocket Lisp Computer]]
+- [[local:/z80/prototype1.html][Prototype 1]]
+- [[local:/z80/prototype2.html][Prototype 2]]
+
+** More technical articles
+- [[local:/z80/spi.html][SPI for microprocessors]]
+
+** External Links
+- [[http://www.z80.info/index.htm][z80.info]] useful z80 resources
+- [[https://www.zilog.com/index.php][Zilog website]]
diff --git a/src/z80/plm.org b/src/z80/plm.org
new file mode 100644
index 0000000..b0eef1d
--- /dev/null
+++ b/src/z80/plm.org
@@ -0,0 +1,66 @@
+#+TITLE: PLM
+#+SUBTITLE: The Pocket Lisp Machine (except its not)
+#+DATE: <2021-03-03>
+#+SETUPFILE: ../../options.org
+
+#+BEGIN_COMMENT
+m4_define(`_REL_HEADER', `Next: <a href="/z80/prototype1.html">Prototype 1</a>Up: <a href="/z80/">Z80</a>')m4_dnl
+#+END_COMMENT
+
+{{{date_place(Bremen, Germany)}}}
+
+* Background
+
+If you have read my article about my first [[local:/z80/prototype1.html][Z80 prototype]], then you
+probably already know, what all of this is about. But, as a small
+recap, the idea of my project is to build a pocket computer that can
+be carried around like the pip-boy from the [[https://en.wikipedia.org/wiki/Fallout_(series)][Fallout]] series.
+
+The exact objectives have changed with the development of the computer
+itself. I soon realized, that the way a user would interacts with a
+pip-boy, was less than optimal. A keyboard was mandatory. I also
+changed my mind about what processor I should use for the project,
+starting with an AVR and later with a Z80.
+
+
+As of right now, the objectives are the following:
+
+* Objectives
+
+- Have a pocket computer, that can be carried like a wrist watch
+
+- It should have as much RAM as its possible with a 8-bit CPU
+
+- It will run a lisp interpreter as its operating system
+
+- It would probably end up being used as a scientific calculator
+
+- It has to be expandable enough, so that I can be used as a pocket
+  Arduino replacement
+
+* Pocket Lisp Machine?
+A lisp machine is a computer design to run lisp code. This means, it
+is optimized to do so, be that through special hardware or ISA.
+
+Under this definition, my computer is no lisp machine. But the name
+refers to the fact that it designed to run a lisp interpreter, scheme
+specifically, as its operating system.
+
+
+* Why don't I use a 6502/65816 instead of a Z80?
+Between a Z80 and a 6502 I definitely prefer the Z80. Mainly because
+of the instruction set and peripherals available.
+
+A 65816 would be easier to program than a Z80 due to the built-in
+support for memory banking. But again, I still prefer the peripherals
+of the Z80.
+
+The Z80 DMA is also a important factor for my decision. While it could
+be used with other processors, I prefer to use it together with the Z80.
+
+The last reason is that, I began building my computer using a Z80 and
+would like to complete this project using the same CPU I started with.
+
+
+I do have the idea of building another computer in the future. This
+time based on a WDC 85C816.
diff --git a/src/z80/prototype1.org b/src/z80/prototype1.org
new file mode 100644
index 0000000..23adec1
--- /dev/null
+++ b/src/z80/prototype1.org
@@ -0,0 +1,78 @@
+#+TITLE: Prototype 1
+#+DATE: <2019-03-03>
+#+SETUPFILE: ../../options.org
+
+#+BEGIN_COMMENT
+m4_define(`_REL_HEADER', `Previous: <a href="/z80/plm.html">PLM</a>
+Next: <a href="/z80/prototype2.html">Prototype 2</a>Up: <a
+href="/z80/">Z80</a>')m4_dnl
+#+END_COMMENT
+
+{{{date_place(Temuco, Chile)}}}@@html:<br>@@ Last edited: Bremen,
+Germany, February 02, 2021
+
+* Background
+
+Back in 2015 I used to watch gameplays of the just released [[https://en.wikipedia.org/wiki/Fallout_4][Fallout 4]].
+From this game the thing I loved the most was the pip-boy, so much so,
+that I had the brilliant idea, /Why don't I build my own pip-boy? I
+mean, How hard could it be?/.
+
+Unsurprisingly, it turned to be harder than expected. I only knew how
+to program at an application level (I wasn't that good at it either)
+and had basically no knowledge of electronics, assembly language, nor
+did I even have the components at my disposal.
+
+* Beginning
+
+Some time after this idea, I got myself an atmel328p and a programmer.
+I learned to instruct this AVR to draw text on a 16x4 lcd and could
+get input from buttons.
+
+But I had some challenges. First, microcontrollers are usually based
+on the Harvard architecture. This means that running programs from ram
+was virtually impossible.
+
+Added to this was the fact that the AVR had only 2K of ram and no way
+to add more. I avoided serial alternatives, because they are slower
+and can't be used as normal RAM inside C code.
+
+These problems were ultimately fixed by switching to a Z80
+microprocessor. The Z80 could in fact handle more memory and run code
+from its RAM, but with it came also the limitation of size. All memory
+had to be external to the chip's package and the processor itself came
+with no peripherals, as microcontrollers usually do.
+
+* First prototype
+
+Three years later, and with the help of many people, I finally
+managed to get all the components and build my first working
+prototype. It did not look beautiful, but it was functional.
+
+#+CAPTION: Prototype 1 together with its serial terminal
+[[https://thomaslabs.org/media/prototype1.jpg]]
+
+I wasn't satisfied with this prototype though. It was not what I had
+envisioned. I wanted to have a pocket computer and this was nothing
+like that. It was huge and full of parts.
+
+* Partial conclusion
+
+Thanks to this project I learned a lot about electronics, programming,
+circuit design and the inner workigs from a computer.
+
+Reinventing the wheel wouldn't have been the only way to acquire this
+knowledge.  But I would definitely recommend it to anyone wanting to
+learn about the internals of computers.
+
+This being said, I can't deny that I still have a lot left to learn.
+
+* The end?
+I wouldn't publish something on the Internet just to say I wasn't able
+to accomplish my dream. Or would I?
+
+It turned out that the idea managed to stay alive long enough, to see
+the day in which I decided to give it another try. This time, hoping
+that the collected knowledge allows me to get further.
+
+This requires its own [[local:/z80/plm.html][series of articles]] though.
diff --git a/src/z80/prototype2.org b/src/z80/prototype2.org
new file mode 100644
index 0000000..ba19bd7
--- /dev/null
+++ b/src/z80/prototype2.org
@@ -0,0 +1,51 @@
+#+TITLE: Prototype 2
+#+DATE: <2021-03-03>
+#+SETUPFILE: ../../options.org
+
+#+BEGIN_COMMENT
+m4_define(`_REL_HEADER', `Next: <ahref="/z80/prototype1.html">Prototype 1</a> Up: <a href="/z80/">Z80</a>')m4_dnl
+#+END_COMMENT
+
+{{{date_place(Bremen, Germany)}}}
+
+#+CAPTION: Prototype 2
+[[https://thomaslabs.org/media/prototype2_1.jpg]]
+
+Because when moving to Bremen, I wasn't able to take my old Prototype
+with me, I had to build a new one. This time though, I needed
+something easily modifiable.
+
+
+One of the disadvantages of my first Prototype, was the fact, that it
+took me around 3 days to build and, because it was soldered, it was
+difficult to modify. This made experimenting with new ideas somewhat
+impractical.
+
+Prototype 2 would be a prototyping tool, as such, it had to be built
+with a technique, that allowed for the electrical stability of a
+soldered circuit, but with the flexibility of a breadboard.
+
+This time I chose the wire wrap assembly technique, as it met all
+requirements.
+
+The following is a list of what I was able to accomplish thanks to
+Prototype 2
+
+- New memory banking system that would allow it to handle up to 4 MiB
+  of memory, instead of the default maximum of 64KiB.
+
+- Add a RTC
+
+- Add video capabilities using a 480x320 18-bit color display
+
+- Dual serial ports with complete modem control lines
+
+#+CAPTION: Prototype 2 together with screen
+[[https://thomaslabs.org/media/prototype2_2.jpg]]
+
+It didn't take long until Prototype 2 became incapable of fulfilling
+its task. Once it was clear, which parts would definitely be part of
+the final design, the flexibility of wire wrapping was no longer
+needed. Added to this, the circuit experimented detrimental voltage
+drops, due to the length of wire used. It was now time to design a
+third prototype, this time using a PCB.
diff --git a/src/z80/spi.org b/src/z80/spi.org
new file mode 100644
index 0000000..d0e55a5
--- /dev/null
+++ b/src/z80/spi.org
@@ -0,0 +1,30 @@
+#+TITLE:  SPI for microprocessors
+#+SETUPFILE: ../../options.org
+
+Bremen, Germany, {{{date}}}
+
+SPI is a useful serial communications interface. It is used in
+hobbyist projects to control from memory ICs to LCD screens and it's
+even possible to read SD cards through it.
+
+Most modern microcontrollers are equiped with built-in SPI support,
+which can be easily used from code without much hardware required. But
+what happends when one wants to interface SPI peripherals with old
+microprocessors? These usually don't have any built-in peripherals and
+, as far as I am aware, there are no enternal peripherals one can buy.
+
+This article aims to provide an overview of how SPI works, the
+instructions on how to build a SPI module for old microprocessors like
+the Z80 and the explanation of how such a module operates.
+
+This is also a part of my ongoing series on the progress of my [[local:/z80][Z80
+based project]].
+
+** Table of Contents
+1) [[#how-does-spi-work][How does SPI work]]
+
+#+NAME: how-does-spi-work
+** 1. How does SPI work
+:PROPERTIES:
+:CUSTOM_ID: how-does-spi-work
+:END: