diff --git a/z80.project/README.md b/z80.project/README.md
index a8e3294..324217e 100644
--- a/z80.project/README.md
+++ b/z80.project/README.md
@@ -1,3 +1,5 @@
 * LINKS
-- Timer 555
-- https://www.digikey.de/de/resources/conversion-calculators/conversion-calculator-555-timer?srsltid=AfmBOooVGYjRDR9IChxvm5S2sqknCEWSG8kwr6jI-XGZyPnTDZY9G8-c
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+- Timer 555 Calculator
+- https://www.digikey.de/de/resources/conversion-calculators/conversion-calculator-555-timer?srsltid=AfmBOooVGYjRDR9IChxvm5S2sqknCEWSG8kwr6jI-XGZyPnTDZY9G8-c
+- Board Simulation
+- https://www.circuitlab.com/editor/#?id=7pq5wm&from=homepage
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