diff --git a/readme.md b/readme.md
index 622575c..75b752f 100644
--- a/readme.md
+++ b/readme.md
@@ -53,10 +53,13 @@ Misc:
 
 ## Memory map / Peripherals
 
-- `00-0F` - 4x4 display
-- `10-1F` - keypad? (details TBD)
-- `20   `    - initial value for IP
-- `20-FF` - free
+- `00   ` - pointer to screen memory
+- `01   ` - pointer to keypad memory
+- `02-0F` - reserved for future use
+- `10-1F` - display (4x4)
+- `20-2F` - keypad? (details TBD)
+- `30   ` - initial value for IP
+- `30-FF` - free
 
 ### Maybe someday