diff --git a/README.md b/README.md
index ee8cbfd..0b4da5c 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,22 @@ We specified some source files (which will get compiled automatically) and some
 
 Furthermore, we can disable subroutines by replacing the first opcode with a RTS (`instant_rts`). This is necessary in some cases because Champ does not emulate hardware and thus can not load data from disk, for example.
 
+### Defining watches
+
+You can watch registers or variables at certain program counter addresses by inserting a _champ directive_ in a comment after the respective code line in your assembler source code. All champ directives start with an _at sign_ (@). Here's an example:
+
+```
+LDA #2         ; load 2 into accumulator
+ASL            ; multiply by two
+STA SOMEWHERE  ; store result @Au
+```
+
+With the `@Au` directive, we tell champ to monitor the A register and interpret it as an unsigned 8 bit integer (likewise, `@As` would treat the value as a signed 8 bit integer). 
+
+By default, all champ values get recorded before the operation has been executed. To get the value after the operation, you can write: `@Au(post)`.
+
+### Running the profiler
+
 To start champ, type:
 
 ```
diff --git a/doc/screenshot.png b/doc/screenshot.png
index 7c4fe1d..36a5c0f 100644
Binary files a/doc/screenshot.png and b/doc/screenshot.png differ
diff --git a/plot3d.yaml b/plot3d.yaml
index ddb69f4..dbf56a7 100644
--- a/plot3d.yaml
+++ b/plot3d.yaml
@@ -1,5 +1,5 @@
 load:
-    0x6000: plot3d/plot3d242c.s
+    0x6000: plot3d/plot3d242.s
     0x1200: plot3d/multtab.s
     0x8400: plot3d/ldrwtab.s
     0x8900: plot3d/SINETABLE