diff --git a/README.md b/README.md
index a337bab..353c602 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,4 @@
 # Arduino Interface
 
 ## Bus Ideas
-- 74HC245, also possible for GPU buffer switching
-
-## PCB
-- Dont forget ZIF footprint
\ No newline at end of file
+- [74HC245](./datasheets/74HC_HCT245.pdf), also possible for GPU buffer switching
diff --git a/notes/arduino.md b/notes/arduino.md
new file mode 100644
index 0000000..3144381
--- /dev/null
+++ b/notes/arduino.md
@@ -0,0 +1,14 @@
+# Arduino Board
+## Capabilities
+- debugging board
+- access to address, data lines + other
+- CPU control lines
+
+## Debugging
+- halt CPU
+- read/write memory
+- get/set paging buffer
+
+## Design
+- [Mega2560](../datasheets/Mega2650PRO.pdf) Arduino Mega compatible board
+- using [ATmega2560](../datasheets/ATmega640-1280-1281-2560-2561.pdf)
diff --git a/notes/color-video.md b/notes/color-video.md
index 987ff59..e826083 100644
--- a/notes/color-video.md
+++ b/notes/color-video.md
@@ -1,5 +1,6 @@
 # Color Video
+- [VGA](./vga.md)
 - 307 200/0x4 B000 Bytes needed
-- 10\*32K RAM chips (AS7C256C-15PCN)
+- 10\*32K RAM chips ([AS7C256C-15PCN](../datasheets/AS7C256C-15PCN.pdf))
 - consider: memory needs to be duplicate
-- TR9C1710
+- [TR9C1710](../datasheets/tr9c1710.pdf)
diff --git a/notes/input-output.md b/notes/input-output.md
index 6322d79..494c5bb 100644
--- a/notes/input-output.md
+++ b/notes/input-output.md
@@ -1,5 +1,5 @@
 # I/O
-- Intel-P8254 (Programmable Interval Timer)
-- NEC-uPB8214C (Priority Interrupt Controller)
-- 6522 (VIA)
-- 6551 (ACIA)
\ No newline at end of file
+- [Intel-P8254](../datasheets/Intel-P8254.pdf) (Programmable Interval Timer)
+- [NEC-uPB8214C](../datasheets/NEC-uPB8214C.pdf) (Priority Interrupt Controller)
+- [6522](../datasheets/w65c02s.pdf) (VIA)
+- [6551](../datasheets/w65c51n.pdf) (ACIA)
\ No newline at end of file
diff --git a/notes/memory-layout.md b/notes/memory-layout.md
index 1792428..6baa8b7 100644
--- a/notes/memory-layout.md
+++ b/notes/memory-layout.md
@@ -12,18 +12,18 @@
 | :----- | :----- | :-- |
 | 0x0000 | 0x7FFF | I/O |
 
-# Persistent Memory (0x01)
+# [Persistent Memory](./persistent-memory.md) (0x01)
 | start  | end    | use     |
 | :----- | :----- | :------ |
 | 0x0000 | 0x7FFF | storage |
 
-# Monochrome Video (0x0E, 0x0F)
+# [Monochrome Video](./monochrome-video.md) (0x0E, 0x0F)
 | start  | end    | use              |
 | :----- | :----- | :--------------- |
 | 0x0000 | 0x4AFF | VRAM             |
 | 0x6000 | 0x7FFF | character memory |
 
-# Color Video (0x10-0x19)
+# [Color Video](./color-video.md) (0x10-0x19)
 | start  | end    | use  | bank      |
 | :----- | :----- | :--- | :-------- |
 | 0x0000 | 0x7FFF | VRAM | 0x10-0x18 |
diff --git a/notes/monochrome-video.md b/notes/monochrome-video.md
index 12c388c..cccb556 100644
--- a/notes/monochrome-video.md
+++ b/notes/monochrome-video.md
@@ -1,4 +1,6 @@
 # Monochrome Video
+- [VGA](./vga.md)
+
 - need 307 200 bits => 38 400/0x9600 Bytes 
 - 8K character memory
 
diff --git a/notes/vga.md b/notes/vga.md
index ccfe88b..b84b676 100644
--- a/notes/vga.md
+++ b/notes/vga.md
@@ -1,4 +1,4 @@
-# VGA
+# VGA ([tinyVGA](http://www.tinyvga.com/vga-timing/640x480@60Hz))
 ## Timings
 ### General Timings
 | Attribute           | Value       |