Update arduino_hid.md

pages/arduino_hid.md

@@ -1,5 +1,8 @@
 # Hardware Arduino HID instead of the OTG
-Using Arduino HID on non-v0 platforms is useful if you need a simple and primitive keyboard emulation device. For example, when used with a hardware KVM switch. You can use the firmware to emulate a USB keyboard and mouse, or for the PS/2 keyboard only.
+Using Arduino HID on non-v0 platforms is useful if you need a simple and primitive keyboard emulation device. For example, when used with a hardware KVM switch. You can use the firmware to emulate:
+* [USB keyboard & mouse](#usb-keyboard--mouse)
+* [PS/2 keyboard only](#ps2-keyboard)
+* [PS/2 keyboard & USB mouse](#ps2-keyboard--usb-mouse)
 
 ## USB keyboard & mouse
 * Build and connect HID according to the [diagram](../README.md#setting-up-the-v0) (the bottom part with transistor, level-shifter and Arduino).
@@ -24,7 +27,7 @@ Using Arduino HID on non-v0 platforms is useful if you need a simple and primiti
 ## PS/2 keyboard
 Using the PS/2 firmware currently has the following limitations:
 * The possibility of using USB HID is excluded.
-* Mouse is not supported due to features of the [PS/2 protocol](https://wiki.osdev.org/PS/2_Mouse).
+* PS/2 mouse is not supported due to features of the [PS/2 protocol](https://wiki.osdev.org/PS/2_Mouse).
 
 Both of these problems will be solved one way or another in the future and the two different firmware versions will be combined into one universal one.
 
@@ -45,3 +48,11 @@ Follow this diagram:
 | Female PS/2 port (front view) | Pinout |
 |-------------------------------|--------|
 | <img src="/img/ps2_kbd.png" alt="drawing" width="200"/> | Arduino pin 7 <-> PS/2 CLOCK<br>Arduino pin 5 <-> PS/2 DATA<br>Arduino GND pin <-> PS/2 GND |
+
+
+## PS/2 keyboard & USB mouse
+This is a mixed mode of HID which is a compromise for old computers. Connections are made simultaneously by both USB and PS/2 pins, as shown in the diagram above. Follow the [PS/2 instructions](#ps2-keyboard), but use these commands to build and install the firmware:
+```
+# make mixed
+# make install
+```