Update README.md and Makefile

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