diff --git a/README.md b/README.md
index b860cdf..b0e6740 100644
--- a/README.md
+++ b/README.md
@@ -35,8 +35,8 @@ There is an experimental and unfinished quick load function using a python termi
 ![Pat80 Memory Monitor](/assets/media/photos/memory_monitor.jpg)
 
 ## Emulator
-The pat80 memory monitor (the os) can be run in a z80 emulator. This repository contains an emulator as submodule, already set up to run the os.
-To try it, head to `pat80-computer/software/z80-assembly/os/` and run `make run` to build the rom from assembly and start the emulator. You will see some windows showing the emulated computer's memory and register status and the pat80 memory monitor prompt.
+The pat80 memory monitor (the os) can be run in a z80 emulator. You can find a very simple one I wrote ad hoc in `pat80-emulator`. It's based (and depends on) the excellent [Z80 emulator library by redcode](https://github.com/redcode/Z80). Follow the instructions on `pat80-emulator/README.md` to build and run it.
+The emulator requires a rom file to run. To obtain a pat80 rom, head to `pat80-computer/software/z80-assembly/os/` and run `make run` to build the rom from assembly and start the emulator. You will see some windows showing the emulated computer's memory and register status and the pat80 memory monitor prompt.
 
 ![Emulator running Memory Monitor](/assets/media/photos/emulator.png)
 
diff --git a/pat80-computer/software/z80-assembly/os/Makefile b/pat80-computer/software/z80-assembly/os/Makefile
index dd56d03..1f159f5 100644
--- a/pat80-computer/software/z80-assembly/os/Makefile
+++ b/pat80-computer/software/z80-assembly/os/Makefile
@@ -1,3 +1,5 @@
+PAT80_EMU_PATH := "../../../../pat80-emulator/build/pat80-emulator"
+
 build:
 	@echo "Building PAT80 rom..."
 	@z80asm -i main.asm -o rom.bin || (exit 1)
@@ -13,5 +15,9 @@ write: build
 	@minipro -w rom.bin -p "AT28C64B"
 
 run: build
-	@echo "Starting emulator..."
-	@../../../../pat80-emulator/z80-python-emulator/src/z80sbc.py -b rom.bin
+	@echo "Starting emulator" $(PAT80_EMU_PATH)
+	@if [ -f "$(PAT80_EMU_PATH)" ]; then\
+        "$(PAT80_EMU_PATH)" "rom.bin";\
+	else\
+		echo -e "\e[31mYou must build the emulator first. Check pat80-emulator/README.md\e[0m";\
+    fi