diff --git a/README.md b/README.md
index e25c801..8282a5d 100644
--- a/README.md
+++ b/README.md
@@ -1,36 +1,153 @@
-Setting up the extra display using sway's hidden [`create_output`](https://github.com/swaywm/sway/blob/master/sway/commands/create_output.c) command, and starting wayvnc
+# CG Virtual Monitor
 
-```
-% swaymsg create_output
-% swaymsg output "HEADLESS-1" resolution 396x224
-% wayvnc -o HEADLESS-1
+This demo showcases how an fx-CG calculator can be used as an external monitor
+by forwarding VNC framebuffers through USB. It was made as a test of the new
+USB driver features introduced in gint 2.10. The program also supports multiple
+parallel monitors and can transmit key presses on calculators back to the PC.
 
-# to remove the output later
-% swaymsg output "HEADLESS-1" unplug
-```
+![](/images/triple-monitor-setup.jpg)
 
-Compiling and starting the VNC client
+## How it works
 
-```
+In this demo, the desktop manager ([sway](https://swaywm.org/)) has two virtual
+outputs not connected to any monitor. The calculators don't act as a physical
+monitors since there is no standard device for that in USB 2 (it's too slow).
+Instead, sway's outputs are exposed by a VNC server running locally
+([wayvnc](https://github.com/any1/wayvnc)).
+
+The VNC client in this repository's `vnc-client` folder is connected to the
+VNC server, while at the same time using the communications library _libfxlink_
+from the [fxSDK](https://gitea.planet-casio.com/Lephenixnoir/fxsdk) to discover
+calculators and exchange messages. It sends framebuffer updates and receives
+keyboard updates (which are, unsurprisingly, forwarded to the VNC server).
+
+The calculators themselves run [gint](https://gitea.planet-casio.com/Lephenixnoir/gint)
+2.10 using newly-added support for host → calculator USB communication. They
+"simply" show framebuffers they receive and send back keyboard updates so that
+the calculator keyboards can control the PC. Obviously the USB driver is not
+that simple... but this is invisible from the application code.
+
+The entire setup runs at about 30 FPS, which each frame taking about:
+
+- 20 ms to receive framebuffers via USB into the VRAM, including
+    * 14 ms of raw reading from the USB buffer;
+    * 6 ms of waiting for data transfer from the host.
+- 11 ms to send the VRAM update to the display.
+
+There are many ways to optimize this further if the need ever arises... I'd be
+surprised if it couldn't run at 60 FPS with double-buffer mode, frame streaming
+and/or parallelizing both bottlenecks by reading directly to the display.
+
+## Download
+
+TODO: Direct link to the .g3a
+
+You'll need to build the VNC client, though.
+
+## Building
+
+Here are the dependencies:
+
+- The [fxSDK](https://gitea.planet-casio.com/Lephenixnoir/fxsdk). The fxSDK
+  repository alone is needed for the VNC client, while the entire tool suite
+  including gint and the cross-compiler is needed to build the add-in.
+- [libvncserver](https://github.com/LibVNC/libvncserver) for the RFB protocol.
+- SDL2 for debug display on the PC.
+
+Build the VNC client with:
+
+```bash
 % cd vnc-client
 % cmake -B build # options...
 % make -C build
-% ./cgvm_vnc --calc
 ```
 
-If you installed native fxSDK tools outside of the default `$HOME/.local`, add `-DFXSDK_PATH=<the path>` to CMake options. (GiteaPC uses the default path.)
+If you installed the fxSDK tools outside of the default `$HOME/.local`, add
+`-DFXSDK_PATH=<the path>` to CMake options. (GiteaPC uses the default path.)
 
-Compiling and installing the virtual monitor add-in
+Build the virtual monitor add-in with:
 
-```
+```bash
 % cd cgvm-addin
+% fxsdk build-cg
+# Send .g3a file to calculator using fxlink and the LINK app:
 % fxsdk build-cg -s
 ```
 
----
+## Using virtual monitors
 
-This entire thing was coded in a few hours with limited regard for exceptions. Ideally, you should
-1. Open the Virtual Monitor add-in on the calculator
-2. Start `cgvm_vnc`
-3. Not disconnect the calculator while `cgvm_vnc` is running
-4. After closing `cgvm_vnc`, disconnect the calculator
+**Step 1: Creating the virtual output**
+
+This step depends on the desktop manager. I'm using sway, which has a hidden
+[`create_output`](https://github.com/swaywm/sway/blob/master/sway/commands/create_output.c)
+command to create and configure headless outputs:
+
+```bash
+# Creating outputs under sway specifically
+% swaymsg create_output
+% swaymsg output "HEADLESS-1" resolution 396x224 # position 1920 0
+
+# For a second monitor:
+% swaymsg create_output
+% swaymsg output "HEADLESS-2" resolution 396x224 # position 1920 224
+```
+
+Other Wayland desktops might have their own way of doing this, though there
+doesn't seem to be a unified method.
+
+On X, [Xvfb](https://www.x.org/releases/X11R7.6/doc/man/man1/Xvfb.1.xhtml)
+seems to allow this (but I'm not sure whether it can run alongside the normal
+display).
+
+**Step 2: Exposing the virtual output on a VNC server**
+
+The VNC client will connect to VNC servers at addresses `127.0.0.1:5900` and
+`127.0.0.1:5910`, whichever is up. This is because wayvnc only exposes a single
+output, so I run two instances to get both monitors.
+
+```bash
+% wayvnc -o "HEADLESS-1" 127.0.0.1 5900
+
+# For a second monitor:
+% wayvnc -o "HEADLESS-2" 127.0.0.1 5910
+```
+
+As the name suggests, wayvnc is for Wayland, but here I'm not worried about
+X-based alternatives.
+
+**Step 3: Run the VNC client and calculator add-in**
+
+Transfer the add-in to the calculator and run it from the main menu. It will
+show "USB connected!" as soon as the PC establishes a connection. Then, start
+the VNC client with:
+
+```bash
+% ./cgvm_vnc --calc # --sdl
+```
+
+You can add `--sdl` to have a copy of the outputs in SDL windows for debugging.
+The VNC client will automatically find calculators exposing the proper USB
+interface and send them the frames.
+
+**Step 4: Stop servers and unplug calculators**
+
+To take the setup down, interrupt the VNC client and close the add-in on the
+calculator with EXIT or MENU (in any order). Then stop the VNC servers, and
+finally remove the outputs.
+
+```bash
+# Removing the outputs under sway specifically
+% swaymsg output "HEADLESS-1" unplug
+
+# For a second monitor:
+% swaymsg output "HEADLESS-2" unplug
+```
+
+## Known issues
+
+- The first frame is often incorrect.
+- Frames from the VNC server are dropped if the calculator is busy processing a
+  previous frame.
+- The VNC client seems to lost connection with the calculator sometimes (libusb
+  returning "No such device"). Not sure why yet, as it's hard to reproduce. In
+  that case restart the VNC client.
diff --git a/images/dual-monitor-setup.jpg b/images/triples-monitor-setup.jpg
similarity index 100%
rename from images/dual-monitor-setup.jpg
rename to images/triples-monitor-setup.jpg