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diff --git a/math/cylindrical_coordinates.org b/math/cylindrical_coordinates.org
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+++ b/math/cylindrical_coordinates.org
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+#+TITLE:Cylindrical Coordinates
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \newcommand{\deriv}[2]{\frac{\text{d}#1}{\text{d}#2}}
+#+LATEX_HEADER: \newcommand{\unitv}[1]{\bm{\hat{e}}_#1}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Coordinate transformations
+\begin{align*}
+x &= r \cos\varphi\\
+y &= r \sin\varphi\\
+z &= z
+\end{align*}
+
+* Local unit vectors
+\begin{align*}
+\unitv{r} &= \cos\theta \unitv{x} + \sin\theta \unitv{y}\\
+\unitv{\theta} &= -\sin\theta \unitv{x} + \cos\theta \unitv{y}\\
+\unitv{z} &= \unitv{z}
+\end{align*}
+* Kinematic in cylindrical coordinates
+** Time derivatives of the local unit vectors
+\begin{align*}
+\deriv{\unitv{r}}{t} &= \dot{\theta}\unitv{\theta}\\
+\deriv{\unitv{\theta}}{t} &= -\dot{\theta}\unitv{r}\\
+\deriv{\unitv{z}}{t} &= 0
+\end{align*}
+** Position vector and its time derivatives
+\begin{align*}
+\bm{r} &= r\unitv{r} + z\unitv{z}\\
+\bm{v} &= \dot{r}\unitv{r} + r\dot\theta\unitv{\theta} + \dot{z}\unitv{z}\\
+\bm{a} &= \left(\ddot{r}-r\dot{\theta}^2\right)\unitv{r} + \left(2\dot{r}\dot{\theta}+r\ddot{\theta}\right)\unitv{\theta} + \ddot{z}\unitv{z}
+\end{align*}
diff --git a/math/derivatives.org b/math/derivatives.org
new file mode 100644
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--- /dev/null
+++ b/math/derivatives.org
@@ -0,0 +1,31 @@
+#+TITLE:Table of Derivatives
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \newcommand{\dcoff}[1]{\frac{\text{d}}{\text{d}x} #1}
+#+LATEX_HEADER: \newcommand{\sdcoff}[1]{\frac{\text{d}#1}{\text{d}x}}
+#+LATEX_HEADER: \newcommand{\deriv}[2]{\frac{\text{d}}{\text{d}x} #1 &= #2}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+
+* General Properties of the Derivative
+Let $f$ and $g$ be real valued functions and $c$ some real constant:
+\begin{align*}
+\dcoff{(cf)} &= c\sdcoff{f}\\
+\dcoff{(f \pm g)} &= \sdcoff{f} \pm \sdcoff{g}\\
+\dcoff{(fg)} &= \sdcoff{f}g + f\sdcoff{g}\\
+\dcoff{\left(\frac{f}{g}\right)} &= \frac{\sdcoff{f}g - f\sdcoff{g}}{g^2}
+\end{align*}
+
+* Trigonometric Funtions
+\begin{align*}
+\deriv{\sin(x)}{\cos(x)}\\
+\deriv{\cos(x)}{-\sin(x)}\\
+\deriv{\tan(x)}{\sec^2(x)}\\
+\deriv{\sec(x)}{\sec(x)\tan(x)}\\
+\deriv{\csc(x)}{\csc(x)\cot(x)}\\
+\deriv{\csc(x)}{-\csc^2(x)}
+\end{align*}
diff --git a/math/index.org b/math/index.org
new file mode 100644
index 0000000..069c4b6
--- /dev/null
+++ b/math/index.org
@@ -0,0 +1,13 @@
+#+TITLE: Math and Physics articles
+#+SETUPFILE: ../math_options.org
+
+- [[file:vectors.org][Cross Product]]
+- [[file:cylindrical_coordinates.org][Cylindrical Coordinates]]
+- [[file:matrices.org][Matrix Properties]]
+- [[file:orbit.org][Orbit]]
+- [[file:polar_coordinates.org][Polar Coordinates]]
+- [[file:spherical_coordinates.org][Spherical Coordinates]]
+- [[file:derivatives.org][Table of Derivatives]]
+- [[file:integrals.org][Table of Integrals]]
+- [[file:levi_cevita.org][The Levi Cevita Symbol]]
+- [[file:trigonometry.org][Trigonometric identities]]
\ No newline at end of file
diff --git a/math/integrals.org b/math/integrals.org
new file mode 100644
index 0000000..6a32903
--- /dev/null
+++ b/math/integrals.org
@@ -0,0 +1,20 @@
+#+TITLE:Table of Integrals
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \newcommand{\intg}[2]{\int #1 \text{d}x &= #2 + C}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+
+* Trigonometric Funtions
+\begin{align*}
+\intg{\sin(x)}{-\cos(x)}\\
+\intg{\cos(x)}{\sin(x)}\\
+\intg{\tan(x)}{-\ln(\cos(x))}\\
+\intg{\sec(x)}{\ln(\sec(x) + \tan(x))}\\
+\intg{\csc(x)}{-\ln(\csc(x) + \cot(x))}\\
+\intg{\cot(x)}{\ln(\sin(x))}
+\end{align*}
diff --git a/math/levi_cevita.org b/math/levi_cevita.org
new file mode 100644
index 0000000..aaa2074
--- /dev/null
+++ b/math/levi_cevita.org
@@ -0,0 +1,26 @@
+#+TITLE: The Levi Cevita Symbol
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Levi Cevita symbol
+\begin{equation*}
+\varepsilon_{ijk} = \left\{\begin{array}{rl}
+1,&(i,j,k) \in \{(1,2,3), (2,3,1), (3,1,2)\}\\
+-1,&(i,j,k) \in \{(3,2,1), (2,1,3), (1,3,2)\}\\
+0,&\text{otherwise}
+\right{}
+\end{array}
+\end{equation*}
+
+\begin{equation*}
+\varepsilon_{ijk} = \varepsilon_{jki} = \varepsilon_{kij} = - \varepsilon_{ikj} = - \varepsilon_{jik} = - \varepsilon_{kji} = 1
+\end{equation*}
+
+\begin{align*}
+\sum_{k=1}^3 \varepsilon_{ijk}\varepsilon_{kmn} = \delta_{im} \delta_{jn} - \delta_{in} \delta_{jm}
+\end{align*}
diff --git a/math/math.css b/math/math.css
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index 0000000..d4e1054
--- /dev/null
+++ b/math/math.css
@@ -0,0 +1,85 @@
+/*
+p.author
+p.date
+p.creator
+.title
+.subtitle
+.todo
+.done
+.WAITING
+.timestamp
+.timestamp-kwd
+.timestamp-wrapper
+.tag
+._HOME
+.target
+.linenr
+.code-highlighted
+div.outline-N
+div.outline-text-N
+.section-number-N
+.figure-number
+.table-number
+.listing-number
+div.figure
+pre.src
+pre.example
+p.verse
+div.footnotes
+p.footnote
+.footref
+.footnum
+.org-svg
+*/
+
+html {
+    height: 100%;
+    color: #cccccc;
+    background-color: hsl(240, 30%, 10%);
+}
+
+body {
+    margin: auto;
+    max-width: 64em;
+    min-height: 100%;
+    display: flex;
+    flex-direction: column;
+    background-color: hsl(240, 30%, 15%);
+}
+
+main {
+    padding: 2em 2em 2em 2em;
+    flex-grow: 1;
+}
+
+h1 {
+    text-align: center;
+}
+
+#content {
+    max-width: 50em;
+    margin: auto;
+}
+
+div.outline-2:first-of-type {
+    padding: 0.25em 1em;
+    background-color: hsl(60,30%,30%);
+}
+
+.equation-container {
+    display: block;
+    padding: 1em 2em;
+    background-color: hsl(240, 30%, 20%);
+    overflow: auto;
+    border: 1px solid hsl(240, 30%, 50%)
+}
+
+img {
+    max-width: unset;
+}
+
+.equation-container img {
+    object-fit: contain;
+    display: block;
+    margin: auto;
+}
diff --git a/math/matrices.org b/math/matrices.org
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index 0000000..a7ba58b
--- /dev/null
+++ b/math/matrices.org
@@ -0,0 +1,32 @@
+#+TITLE:Matrix Properties
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Basic properties
+\begin{align*}
+A + B = B + A
+\end{align*}
+* Dot product
+\begin{align*}
+(A^\text{T})^\text{T} &= A\\
+(A + B)^\text{T} &= A^\text{T} + B^\text{T}\\
+(AB)^\text{T} &= B^\text{T}A^\text{T}
+\end{align*}
+* Transpose
+\begin{align*}
+\bm{a} \cdot \bm{b} &= \overline{\bm{b}} \cdot \bm{a}\\
+\bm{a} \cdot \bm{b} &= \bm{a}^\text{T} \bm{b}
+\end{align*}
+
+* Hermitian transpose
+\begin{align*}
+A^\ast &= \left[\overline{a_{ij}}\right]\\
+(\lambda A)^\ast &= \left[\overline{\lambda a_{ij}}\right] = \overline{\lambda} \left[a_{ij}\right]^\ast = \overline{\lambda}\,\overline{A}\\
+A^\dag &= (A^\ast)^\text{T}\\
+A^{\dag\dag} &= A
+\end{align*}
diff --git a/math/orbit.org b/math/orbit.org
new file mode 100644
index 0000000..88079a6
--- /dev/null
+++ b/math/orbit.org
@@ -0,0 +1,93 @@
+#+TITLE:Orbit
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \usepackage{amssymb}
+#+LATEX_HEADER: \newcommand{\deriv}[2]{\frac{\text{d}#1}{\text{d}#2}}
+#+LATEX_HEADER: \newcommand{\unitv}[1]{\bm{\hat{e}}_#1}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Deriving Kepler's first law from Newton's law of universal gravitation
+
+The movement of an object with mass $m$ orbiting another body with mass $M$ is
+given by Newton's law of gravitation. If $m \ll M$ it is possible to consider
+the position of the larger object constant and use it as the origin of our
+coordinate system. Then the following equation applies for movement of the
+smaller object:
+
+\begin{equation*}
+m\ddot{\bm{r}} = - \frac{GMm}{r^3}\bm{r} \Leftrightarrow \ddot{\bm{r}} = - \frac{GM}{r^3}\bm{r}
+\end{equation*}
+
+In order to solve this differential equation we first consider the angular
+momentum of or object around its orbit.
+
+\begin{equation*}
+\bm{L} = \bm{r} \times m \dot{\bm{r}}
+\end{equation*}
+
+In the abscense of external toques, because the only force acting on the object
+is parallel to its position, the angular momentum is conserved.
+
+\begin{equation*}
+\deriv{\bm{L}}{t} = \dot{\bm{r}} \times m \dot{\bm{r}} + \bm{r} \times m \ddot{\bm{r}} = 0
+\end{equation*}
+
+We now multiply both sides of our equation from the right by the angular
+momentum and develop the right side of the equation using vector identities.
+
+\begin{align*}
+\ddot{\bm{r}} \times \bm{L} &= -GM\frac{\bm{r} \times \left(\bm{r} \times m \dot{\bm{r}}\right)}{r^3}\\
+&= - \frac{GMm}{r^3} \left(\left(\bm{r} \cdot \dot{\bm{r}}\right)\bm{r} - \left(\bm{r} \cdot \bm{r}\right)\dot{\bm{r}}\right)\\
+&= GMm\left(\frac{\left(\bm{r} \cdot \bm{r}\right)\dot{\bm{r}}}{r^3} - \frac{\left(\bm{r} \cdot \dot{\bm{r}}\right)\bm{r}}{r^3}\right)\\
+&= GMm\left(\frac{\dot{\bm{r}}}{r} - \frac{\left(\bm{r} \cdot \dot{\bm{r}}\right)\bm{r}}{r^3}\right)\\
+&= GMm\left(\frac{1}{r} \deriv{\bm{r}}{t} + \deriv{}{t}\left(\frac{1}{r}\right)\bm{r}\right)\\
+&= GMm\deriv{}{t}\left(\frac{\bm{r}}{r}\right)
+\end{align*}
+
+We observe that each side of our equation is a derivative of a quantity. We know
+integrate both sides and take the integrations constant into account.
+
+\begin{align*}
+& \deriv{}{t} \left(\dot{\bm{r}} \times \bm{L}\right) = GM \deriv{}{t}\left(\frac{\bm{r}}{r}\right)\\
+\Leftrightarrow \quad & \dot{\bm{r}} \times \bm{L} = GM \frac{\bm{r}}{r} + \bm{a}
+\end{align*}
+
+Our objective is now to solve the equation for $r$, so we multiply both sides by $\bm{r}$:
+
+\begin{align*}
+\dot{\bm{r}} \times \left(\bm{r} \times \dot{\bm{r}}\right) &= GM \frac{\bm{r}}{r} + \bm{a}\\
+\bm{r} \cdot \left(\dot{\bm{r}} \times \left(\bm{r} \times \dot{\bm{r}}\right)\right) &= GMr + \bm{r} \cdot \bm{a}
+\end{align*}
+
+By applying a cyclic permutation of the resulting triple product and using the
+known property of the scalar product we now express the equation only in terms
+of the magnitudes of the vectors.
+
+\begin{align*}
+\left(\bm{r} \times \dot{\bm{r}}\right) \cdot \left(\bm{r} \times \dot{\bm{r}}\right) &= GMr + \bm{r} \cdot \bm{a}\\
+\left(\frac{L}{m}\right)^2 &= GMr + \bm{r} \cdot \bm{a}\\
+\left(\frac{L}{m}\right)^2 &= GMr + r a \cos\theta
+\end{align*}
+
+The last steps are to solve for $r$
+
+\begin{align*}
+r &= \left(\frac{L}{m}\right)^2 \frac{1}{GM + a \cos\theta}\\
+&= \left(\frac{L}{m}\right)^2 \frac{1}{GM} \frac{1}{1 + \frac{a}{GM} \cos\theta}\\
+&= \left(\frac{L}{m}\right)^2 \frac{1}{GM} \frac{1}{1 + e\cos\theta}
+\end{align*}
+
+Finally we reach our result. Objects orbiting according to Newton's Law of
+Gravitation follow paths that correspond to the conic sections. Here is Kepler's
+first Law a special case, where our object has a stable orbit around the larger
+body.
+
+\begin{equation*}
+r &= \frac{L^2}{GM m^2} \frac{1}{1 + e\cos\theta}
+\end{equation*}
+
+* Deriving a physical interpretation of the excentricity of the orbit
diff --git a/math/polar_coordinates.org b/math/polar_coordinates.org
new file mode 100644
index 0000000..ff07be3
--- /dev/null
+++ b/math/polar_coordinates.org
@@ -0,0 +1,36 @@
+#+TITLE:Polar Coordinates
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \newcommand{\deriv}[2]{\frac{\text{d}#1}{\text{d}#2}}
+#+LATEX_HEADER: \newcommand{\unitv}[1]{\bm{\hat{e}}_#1}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Coordinate transformations
+\begin{align*}
+x &= r \cos\theta\\
+y &= r \sin\theta
+\end{align*}
+
+* Local unit vectors
+\begin{align*}
+\unitv{r} &= \cos\theta \unitv{x} + \sin\theta \unitv{y}\\
+\unitv{\theta} &= -\sin\theta \unitv{x} + \cos\theta \unitv{y}
+\end{align*}
+
+* Kinematic in polar coordinates
+** Time derivatives of the local unit vectors
+\begin{align*}
+\deriv{\unitv{r}}{t} &= \dot{\theta}\unitv{\theta}\\
+\deriv{\unitv{\theta}}{t} &= -\dot{\theta}\unitv{r}
+\end{align*}
+** Position vector and its time derivatives
+\begin{align*}
+\bm{r} &= r\unitv{r}\\
+\bm{v} &= \dot{r}\unitv{r} + r\dot\theta\unitv{\theta}\\
+\bm{a} &= \left(\ddot{r} - r\dot\theta^2\right)\unitv{r}
++ \left(2\dot{r}\dot\theta + r\ddot\theta\right)\unitv{\theta}
+\end{align*}
diff --git a/math/spherical_coordinates.org b/math/spherical_coordinates.org
new file mode 100644
index 0000000..1c7fd9c
--- /dev/null
+++ b/math/spherical_coordinates.org
@@ -0,0 +1,39 @@
+#+TITLE:Spherical Coordinates
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+#+LATEX_HEADER: \newcommand{\deriv}[2]{\frac{\text{d}#1}{\text{d}#2}}
+#+LATEX_HEADER: \newcommand{\unitv}[1]{\bm{\hat{e}}_#1}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+* Coordinate transformations
+\begin{align*}
+x &= r \sin\theta \cos\varphi\\
+y &= r \sin\theta \sin\varphi\\
+z &= r \cos\theta
+\end{align*}
+
+* Local unit vectors
+\begin{align*}
+\bm{\hat{e}}_r &= \sin\theta \cos\varphi \bm{\hat{e}}_x + \sin\theta \sin\varphi \bm{\hat{e}}_y + \cos\theta \bm{\hat{e}}_z\\
+\bm{\hat{e}}_\theta &= \cos\theta \cos\varphi \bm{\hat{e}}_x + \cos\theta \sin\varphi \bm{\hat{e}}_y - \sin\theta \bm{\hat{e}}_z\\
+\bm{\hat{e}}_\varphi &= - \sin\theta \sin\varphi \bm{\hat{e}}_x + \sin\theta \cos\varphi \bm{\hat{e}}_y
+\end{align*}
+* Kinematic in spherical coordinates
+** Time derivatives of the local unit vectors
+\begin{align*}
+\deriv{\unitv{r}}{t} &= \dot{\theta}\unitv{\theta} + \dot{\varphi}\sin\theta \unitv{\varphi}\\
+\deriv{\unitv{\theta}}{t} &= -\dot{\theta}\unitv{r} + \dot{\varphi}\cos\theta \unitv{\varphi}\\
+\deriv{\unitv{\varphi}}{t} &= -\dot{\varphi} \left(\sin\theta\unitv{r} + \cos\theta\unitv{\theta}\right)
+\end{align*}
+** Position vector and its time derivatives
+\begin{align*}
+\bm{r} &= r\unitv{r}\\
+\bm{v} &= \dot{r}\unitv{r} + r\dot\theta\unitv{\theta} + r\dot\varphi\sin\theta\unitv{\varphi}\\
+\bm{a} &= \left(\ddot{r} - r\dot\theta^2 - r\dot\varphi^2\sin^2\theta\right)\unitv{r}
++ \left(2\dot{r}\dot\theta + r\ddot\theta - r\dot\varphi^2\sin\theta\cos\theta\right)\unitv{\theta}
++ \left(2\dot{r}\dot\varphi\sin\theta + 2r\dot\theta\dot\varphi\cos\theta + r\ddot\varphi\sin\theta\right)\unitv{\varphi}
+\end{align*}
diff --git a/math/trigonometry.org b/math/trigonometry.org
new file mode 100644
index 0000000..3e81eeb
--- /dev/null
+++ b/math/trigonometry.org
@@ -0,0 +1,51 @@
+#+TITLE:Trigonometric identities
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+
+* Pythagorean identities
+\begin{align*}
+&\cos^2\left(x\right) + \sin^2\left(x\right) = 1\\
+&\tan^2\left(x\right) + 1                    = \sec^2\left(x\right)\\
+&1                    + \cot^2\left(x\right) = \csc^2\left(x\right)
+\end{align*}
+* Sum of angles
+\begin{align*}
+&\sin\left(a \pm b\right) = \sin\left(a\right)\cos\left(b\right) \pm \cos\left(a\right)\sin\left(b\right)\\
+&\cos\left(a \pm b\right) = \cos\left(a\right)\cos\left(b\right) \mp \sin\left(a\right)\sin\left(b\right)\\
+&\tan(a \pm b) = \frac{\tan(a) \pm \tan(b)}{1 \mp \tan(a) \tan(b)}
+\end{align*}
+* Multiple angles
+\begin{align*}
+&\sin(2\theta) = 2\sin(\theta)\cos(\theta)\\
+&\cos(2\theta) = \cos^2\theta - \sin^2\theta = 2\cos^2\theta - 1 = 1 - 2\sin^2\theta
+\end{align*}
+* Half-angle formulae
+\begin{align*}
+&\sin \frac{\theta}{2} = \pm \sqrt{\frac{1-\cos\theta}{2}}\\
+&\cos \frac{\theta}{2} = \pm \sqrt{\frac{1+\cos\theta}{2}}
+\end{align*}
+* Power-reduction formulae
+\begin{align*}
+&\sin^2\theta = \frac{1 - \cos(2\theta)}{2}\\
+&\cos^2\theta = \frac{1 + \cos(2\theta)}{2}
+\end{align*}
+* Product-to-sum formulae
+\begin{align*}
+&2 \cos\theta \cos\varphi = \cos(\theta-\varphi) + \cos(\theta+\varphi)\\
+&2 \sin\theta \sin\varphi = \cos(\theta-\varphi) - \cos(\theta+\varphi)\\
+&2 \sin\theta \cos\varphi = \sin(\theta+\varphi) + \sin(\theta-\varphi)\\
+&2\cos\theta\sin\varphi = \sin(\theta+\varphi) - \sin(\theta-\varphi)
+\end{align*}
+* Sum-to-product formulae
+\begin{align*}
+&\sin\theta \pm \sin\varphi = 2 \sin\left(\frac{\theta\pm\varphi}{2}\right) \cos\left(\frac{\theta\mp\varphi}{2}\right)\\
+&\cos\theta + \cos\varphi = 2 \cos\left(\frac{\theta+\varphi}{2}\right) \cos\left(\frac{\theta-\varphi}{2}\right)\\
+&\tan\theta \pm \tan\varphi = \frac{\sin(\theta\pm\varphi)}{\cos\theta \cos\varphi}\\
+&\cos\theta - \cos\varphi = - 2 \sin\left(\frac{\theta+\varphi}{2}\right) \sin\left(\frac{\theta-\varphi}{2}\right)
+\end{align*}
diff --git a/math/vectors.org b/math/vectors.org
new file mode 100644
index 0000000..49d8132
--- /dev/null
+++ b/math/vectors.org
@@ -0,0 +1,58 @@
+#+TITLE:Cross Product
+#+SETUPFILE: ../math_options.org
+#+LATEX_HEADER: \usepackage{bm}
+#+LATEX_HEADER: \usepackage{mathtools}
+
+* Disclaimer
+This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are)
+
+* Definition
+We shall define the cross product in terms of two properties we are
+interested in:
+
+- Distributive: $\bm{a} \times \left(\bm{b} + \bm{c}\right) = \bm{a} \times \bm{b} + \bm{a} \times \bm{c}$
+- Orthogonal: $\bm{a} \times \bm{b} = \bm{c} \implies \bm{c} \cdot \bm{a} = \bm{0} \land \bm{c} \cdot \bm{b} = \bm{0}$
+
+It is worth mentioning that given a pair of vectors in $\mathbb{R}^3$
+there exist an infinite amount of vectors that satisfy these
+properties, so it is also necessary to introduce the following
+relations between the basis vectors to properly define the cross
+product.
+
+\begin{align*}
+\bm{e}_1 &= \bm{e}_2 \times \bm{e}_3\\
+\bm{e}_2 &= \bm{e}_3 \times \bm{e}_1\\
+\bm{e}_3 &= \bm{e}_1 \times \bm{e}_2\\
+\bm{e}_i \times \bm{e}_i &= \bm{0},\qquad\text{For}\quad i = 1,2,3
+\end{align*}
+
+We introduce the Levi-Civita symbol to condense our calculations.
+
+\begin{equation*}
+\epsilon_{ijk} \coloneqq \bm{e}_i \cdot \left(\bm{e}_j \times \bm{e}_k\right)
+\end{equation*}
+
+Based on this we may now derive a way to compute the cross product of
+two vectors
+
+\begin{align*}
+\left[\bm{a} \times \bm{b}\right]_i &= \left[\left(\sum_j a_j \bm{e}_j\right) \times \left(\sum_k b_k \bm{e_k}\right)\right]_i\\
+&= \left[\sum_{jk} a_j b_k \left(\bm{e}_j \times \bm{e}_k\right)\right]_i\\
+&= \sum_{jk} a_j b_k \bm{e}_i \cdot \left(\bm{e}_j \times \bm{e}_k\right)\\
+&= \sum_{jk} \epsilon_{ijk} a_j b_k\\
+\bm{a} \times \bm{b} &= \sum_{ijk} \epsilon_{ijk} a_i b_j \bm{e}_k
+\end{align*}
+
+* Properties
+\begin{align*}
+&\bm{a} \times \bm{b} = - \bm{b} \times \bm{a}\\
+&\bm{a} \cdot \left(\bm{b} \times \bm{c}\right)
+= \bm{b} \cdot \left(\bm{c} \times \bm{a}\right)
+= \bm{c} \cdot \left(\bm{a} \times \bm{b}\right)\\
+&\bm{a} \times \left(\bm{b} \times \bm{c}\right)
+= \left(\bm{a} \cdot \bm{c}\right)\bm{b} - \left(\bm{a} \cdot \bm{b}\right)\bm{c}\\
+&\left(\bm{a} \times \bm{b}\right) \times \left(\bm{c} \times \bm{d}\right)
+= \left(\bm{a}\cdot\bm{c}\right) \left(\bm{b}\cdot\bm{d}\right) - \left(\bm{a}\cdot\bm{d}\right) \left(\bm{b}\cdot\bm{c}\right)
+\end{align*}
diff --git a/math_options.org b/math_options.org
new file mode 100644
index 0000000..5fd9baa
--- /dev/null
+++ b/math_options.org
@@ -0,0 +1,5 @@
+#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="/style.css" />
+#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="/math.css" />
+#+HTML_HEAD_EXTRA: <meta name="author" content="Thomas Albers Raviola">
+#+HTML_HEAD_EXTRA: <meta name="description" content="Hobbyist electronics, programming and more">
+#+MACRO: date_place $1, $2, {{{date(%B %d\, %Y)}}}
diff --git a/options.org b/options.org
new file mode 100644
index 0000000..234c394
--- /dev/null
+++ b/options.org
@@ -0,0 +1,4 @@
+#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="/style.css" />
+#+HTML_HEAD_EXTRA: <meta name="author" content="Thomas Albers Raviola">
+#+HTML_HEAD_EXTRA: <meta name="description" content="Hobbyist electronics, programming and more">
+#+MACRO: date_place $1, $2, {{{date(%B %d\, %Y)}}}
diff --git a/publish.el b/publish.el
new file mode 100755
index 0000000..a327d02
--- /dev/null
+++ b/publish.el
@@ -0,0 +1,205 @@
+#!/usr/bin/env -S emacs -Q --batch --script
+
+(require 'ox)
+(require 'esxml)
+
+(defun thomaslabs-navbar ()
+  (sxml-to-xml
+   `(nav
+     (ul
+      (li (a (@ (href "/"))
+             "Home"))
+      (li (a (@ (href "/z80/"))
+             "Z80"))
+      (li (a (@ (href "/programs/"))
+             "programs"))
+      (li (a (@ (href "/math/"))
+             "math"))
+      (li (a (@ (href "/privacy.html"))
+             "contact &amp; privacy policy"))))))
+
+(defun thomaslabs-footer ()
+  (sxml-to-xml
+   `(footer
+     (p
+      "Copyright © 2021 - 2022 Thomas Albers Raviola"
+      (br)
+      "This website and its contents are published under the
+following licences, unless otherwise specified"
+      (ul
+       (li "Website and images:"
+           (a (@ (href "https://creativecommons.org/licenses/by-nc-sa/4.0/"))
+              "CC BY-NC-SA 4.0"))
+       (li "Schematics:"
+           (a (@ (href "https://creativecommons.org/licenses/by-nc-nd/4.0/"))
+              "CC BY-NC-ND 4.0"))
+       (li "Code:"
+           (a (@ (href "https://www.gnu.org/licenses/gpl-3.0.html"))
+              "GPL-3.0")))))))
+
+(defun thomaslabs-template (contents info)
+  (concat
+   "<!DOCTYPE html>\n"
+   (sxml-to-xml
+    `(html (@ (lang "en"))
+           (head
+            ,(org-html--build-meta-info
+              `(:title ,(if (plist-get info :title)
+                            (format "Thomas' Labs | %s" (car (plist-get info :title)))
+                          "Thomas' Labs")
+                       ,@info))
+            ,(org-html--build-head info))
+           (body
+            ,(if-let ((title (plist-get info :title)))
+                 `(header
+                   (p "Thomas' Labs")
+                   (h1 ,(org-export-data title info)))
+               `(header
+                 (h1 "Thomas' Labs")))
+            ,(thomaslabs-navbar)
+            (div (@ (class "content"))
+                 (main
+                  (article ,contents)))
+            (hr)
+            ,(thomaslabs-footer))))))
+
+(defun math-preamble (&rest args)
+  (sxml-to-xml
+   '(div
+     (h2 "Disclaimer")
+     (p "This site as of now just a technology demonstration and its claims
+should not be taken as true (even though I myself am pretty confident
+they are"))))
+
+(defun math-sitemap (title entries)
+  (concat (format "#+TITLE: %s\n#+SETUPFILE: ../math_options.org\n\n" title)
+          (org-list-to-org entries)))
+
+
+(defun org-local-link-export (link description format info)
+  (format "<a href=\"%s\">%s</a>"
+          link
+          description))
+
+(defun org-img-link-export (link description format info)
+  (message "%s" info)
+  (format "<a href=\"%s\">%s</a>"
+          link
+          description))
+
+(defun org-local-link-follow (&rest args)
+  t)
+
+(org-link-set-parameters "local"
+                         :follow #'org-local-link-follow
+                         :export #'org-local-link-export)
+
+(org-link-set-parameters "img"
+                         :follow #'org-local-link-follow
+                         :export #'org-img-link-export)
+
+(org-export-define-derived-backend 'thomaslabs-html 'html
+  :translate-alist
+  '((template . thomaslabs-template)))
+
+(defun thomaslabs-publish-to-html (plist filename pub-dir)
+  "Publish an org file to HTML, using the FILENAME as the output directory."
+  (org-publish-org-to 'thomaslabs-html
+                      filename
+                      ".html"
+                      plist
+                      pub-dir))
+
+(setq org-publish-project-alist
+      `(("thomaslabs_html"
+         :base-directory "~/Code/websites/thomaslabs/src"
+         :publishing-directory "/srv/web/thomaslabs"
+         :publishing-function thomaslabs-publish-to-html
+         :with-toc nil
+         :recursive t
+
+         :language "en_US"
+
+         :html-head-include-default-style nil
+         :html-head-include-scripts nil
+         :html-preamble nil
+         :html-postamble nil
+         :html-use-infojs nil
+         :html-html5-fancy t
+         :html-doctype "html5"
+         :with-toc nil
+         :section-numbers nil
+         :with-latex dvisvgm)
+
+        ("math_html"
+         :base-directory "~/Code/websites/thomaslabs/math"
+         :publishing-directory "/srv/web/thomaslabs/math"
+         :publishing-function thomaslabs-publish-to-html
+         :with-toc nil
+         :recursive t
+
+         :language "en_US"
+
+         :html-head-include-default-style nil
+         :html-head-include-scripts nil
+         :html-preamble math-preamble
+         :html-postamble nil
+         :html-use-infojs nil
+         :html-html5-fancy t
+         :html-doctype "html5"
+         :with-toc nil
+
+         :auto-sitemap t
+         :sitemap-filename "index.org"
+         :sitemap-title "Math and Physics articles"
+         :sitemap-function math-sitemap
+
+         :section-numbers nil
+         :with-latex dvisvgm)
+
+        ("math_svg"
+         :base-directory "~/Code/websites/thomaslabs/math/ltximg"
+         :base-extension "svg"
+         :publishing-directory "/srv/web/thomaslabs/math/ltximg"
+         :publishing-function org-publish-attachment)
+
+        ("math_css"
+         :base-directory "~/Code/websites/thomaslabs/math"
+         :base-extension "css"
+         :publishing-directory "/srv/web/thomaslabs"
+         :publishing-function org-publish-attachment)
+
+        ("thomaslabs_css"
+         :base-directory "~/Code/websites/thomaslabs/src"
+         :base-extension "css"
+         :publishing-directory "/srv/web/thomaslabs"
+         :publishing-function org-publish-attachment)
+
+        ("thomaslabs_media"
+         :base-directory "~/Code/websites/thomaslabs/media"
+         :base-extension "jpg\\|gif\\|png"
+         :publishing-directory "/srv/web/thomaslabs/media"
+         :publishing-function org-publish-attachment)
+
+        ("thomaslabs"
+         :components ("thomaslabs_html"
+                      "thomaslabs_media"
+                      "thomaslabs_css"))
+
+        ("thomaslabs_math"
+         :components ("math_html"
+                      "math_css"
+                      "math_svg"))))
+
+(plist-put org-format-latex-options :html-foreground "#cccccc")
+
+(org-publish "thomaslabs" t)
+(org-publish "thomaslabs_math" t)
+
+;; (let ((opt "--delete -Prlpte 'ssh -p 1764'")
+;;       (src "'/srv/web/thomaslabs/'")
+;;       (dst "'root@thomaslabs.org:/var/www/math/'"))
+;;   (call-process-shell-command (format "rsync %s %s %s" opt src dst)))
+
+;; (org-publish "thomaslabs" t)
+;; (org-publish "math_svg" t)
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: