diff --git a/README.md b/README.md
index 42202dc..afef3b3 100644
--- a/README.md
+++ b/README.md
@@ -43,8 +43,9 @@ for more information about this functional test suite).
 
 ## 3.0 Features
 
-Symon can simulate multiple 6502 based architectures. At present, two
-machines are implemented: Symon (the default), and MULTICOMP.
+Symon can simulate multiple 6502 based architectures. At present, three
+machines are implemented: Symon (the default), MULTICOMP, and a "Simple"
+machine useful for debugging.
 
 ### 3.1 Memory Maps
 
@@ -65,6 +66,10 @@ memory.
   - `$E000`--`$FFFF`: 8KB ROM
   - `$FFD0`--`$FFD1`: Motorola 6850 ACIA
 
+### 3.1.3 Simple Memory Map
+
+  - `$0000`--`$FFFF`: 64KB RAM
+
 ### 3.2 Serial Console and CPU Status
 
 ![Serial Console] (https://github.com/sethm/symon/raw/master/screenshots/console.png)