diff --git a/doc/README.md b/doc/README.md
index c02e3e4..e76a7aa 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -19,8 +19,6 @@ Table of contents:
   * [Development](development.md): Development environment, building, releasing, etc.
   * [Developer documentation](dev/README.md): Various lose documentation/notes by developers
   * [Tools](tools/README.md): Documentation for additional user and development tooling
-* Hardware
-  * [Hardware](hardware/README.md): Anything related to hardware, e.g. IO boards
 
 ## Further external documentation
 
diff --git a/doc/hardware/bio2-sub-io-turntable-bypass-cable.md b/doc/hardware/bio2-sub-io-turntable-bypass-cable.md
deleted file mode 100644
index 1273735..0000000
--- a/doc/hardware/bio2-sub-io-turntable-bypass-cable.md
+++ /dev/null
@@ -1,55 +0,0 @@
-# BIO2 sub IO turntable bypass cable
-If you upgraded a C02 wired cabinet, the turntables are connected to the
-sub IO via a serial line that goes to another sub IO behind the front panel
-next to the 16seg display. This introduces additional latency as the input
-data needs to pass through multiple systems/PCBs until it reaches the game.
-
-This can be reduced by using a so-called "bypass" cable, that connects the
-turntables directly to the BIO2 sub IO board by emulating the wiring of a
-D01 cabinet, reducing latency significantly.
-
-This cable could be ordered with the IIDX Rootage upgrade kit but can also
-be easily created from scratch.
-
-## Parts
-* Some wires
-* [JST HL](https://jst.de/file/download/219/pitch-3-96-mm-wtw-hl2-pdf) 2x4 pin female connector
-* [JST HVQ](https://jst.de/file/download/637/hvq) 8 pin female connector
-* Matching terminals for the connectors
-
-## Pinout
-```text
-JST HL 2x4 pin front view connector
-
-notch at top
-    ___
-|---------|
-| 1 2 3 4 |
-| 5 6 7 8 |
-|---------|
-```
-
-```
-JST HVQ 8 pin front view connector
-Numbering on connector matches
-
-   notch at top
-___________________
--------------------
-|-----------------|
-| 1 2 3 4 5 6 7 8 |
-|-----------------|
-
-```
-
-Pins of the two connectors need to be connected like this:
-| JST HL 2x4 pin | JST 8 pin |
-|----------------|-----------|
-| 1              | 1         |
-| 2              | 1         |
-| 3              | 3         |
-| 4              | 2         |
-| 5              | 5         |
-| 6              | 4         |
-| 7              | 8         |
-| 8              | 8         |
diff --git a/doc/hardware/ezusb-iidx-rj45-to-din8-pinout.md b/doc/hardware/ezusb-iidx-rj45-to-din8-pinout.md
deleted file mode 100644
index a2e98d3..0000000
--- a/doc/hardware/ezusb-iidx-rj45-to-din8-pinout.md
+++ /dev/null
@@ -1,51 +0,0 @@
-# Ezusb 1/2 RJ45 to DIN8 connector pinout
-This was created from using the BIO2 sub IO board to connect pre IIDX 25 cabinet hardware to the
-BIO2 IO board. The two connector types from different generation IO boards, RJ45 on the ezusb FX
-(C02) board and a round DIN8 connector on the ezusb FX2 (IO2) board are just different connectors to
-the same hardware on the PCB.
-
-Therefore, any C02 wired cabinet can be easily upgraded to IO2 wiring and vice versa by building
-a simple RJ45 -> DIN8 or DIN8 -> RJ45 adapter.
-
-The following connection information was traced on a original Konami BIO2 sub IO board.
-
-RJ45 (female) connector, top view:
-```text
-plug insert
-     |
-     |
-     v
-|-----------|
-|  Top view |
-|           |
-|   Pins    |    
-|   7 5 3 1 |
-|  8 6 4 2  |
-|-----------|
-```
-
-DIN8 (female) connector, top view:
-```text
-plug insert
-     |
-     |
-     v
-|-----------|
-|  Top view |
-|   Pins    |    
-|  3  1 2 6 |
-| 7 4 5 8 9 |
-|-----------|
-```
-
-The two connectors are interconnected on the PCB like this:
-| RJ45 pins | DIN8 pins |
-|-----------|-----------|
-| 1         | 1         |
-| 2         | 7         |
-| 3         | 4         |
-| 4         | 6         |
-| 5         | 5         |
-| 6         | 3         |
-| 7         | 2         |
-| 8         | 1         |
\ No newline at end of file