diff --git a/book/000-Book-Format b/book/000-Book-Format
new file mode 100644
index 0000000..ea86bca
--- /dev/null
+++ b/book/000-Book-Format
@@ -0,0 +1,12 @@
+Formatting uses Markdown.
+
+# Chapter Title
+
+## Section Title
+
+Paragraph text.
+
+```
+example code
+```
+
diff --git a/book/Building-BSD b/book/Building-BSD
index e69de29..c55b67c 100644
--- a/book/Building-BSD
+++ b/book/Building-BSD
@@ -0,0 +1,25 @@
+# Building RETRO
+
+## Requirements
+
+- c compiler (tested: clang, tcc, gcc)
+- make
+- standard unix shell
+
+## Process
+
+Run `make`.
+
+This will build the toolchain and then the main `retro`
+executable.
+
+## Executables
+
+In the `bin/` directory:
+
+    retro
+    retro-unu
+    retro-muri
+    retro-extend
+    retro-embedimage
+
diff --git a/book/Building-Linux b/book/Building-Linux
index e69de29..c6aacea 100644
--- a/book/Building-Linux
+++ b/book/Building-Linux
@@ -0,0 +1,25 @@
+# Building RETRO
+
+## Requirements
+
+- c compiler (tested: clang, tcc, gcc)
+- make
+- standard unix shell
+
+## Process
+
+Run `make -f Makefile.linux`.
+
+This will build the toolchain and then the main `retro`
+executable.
+
+## Executables
+
+In the `bin/` directory:
+
+    retro
+    retro-unu
+    retro-muri
+    retro-extend
+    retro-embedimage
+
diff --git a/book/Building-Windows b/book/Building-Windows
index e69de29..79593ac 100644
--- a/book/Building-Windows
+++ b/book/Building-Windows
@@ -0,0 +1,19 @@
+## C#: retro.cs
+
+This is an implementation of `retro-repl` in C#. As with
+`retro-repl` it requires the `ngaImage` in the current
+directory when starting.
+
+Building:
+
+    csc retro.cs
+
+You'll need to make sure your path has the CSC.EXE in it,
+or provide a full path to it. Something like this should
+reveal the path to use:
+
+    dir /s %WINDIR%\CSC.EXE
+
+I've only tested building this using Microsoft's .NET tools.
+It should also build and run under Mono.
+
diff --git a/book/Building-macOS b/book/Building-macOS
index e69de29..c55b67c 100644
--- a/book/Building-macOS
+++ b/book/Building-macOS
@@ -0,0 +1,25 @@
+# Building RETRO
+
+## Requirements
+
+- c compiler (tested: clang, tcc, gcc)
+- make
+- standard unix shell
+
+## Process
+
+Run `make`.
+
+This will build the toolchain and then the main `retro`
+executable.
+
+## Executables
+
+In the `bin/` directory:
+
+    retro
+    retro-unu
+    retro-muri
+    retro-extend
+    retro-embedimage
+