diff --git a/src/main/scala/millfork/compiler/mos/ComparisonType.scala b/src/main/scala/millfork/compiler/ComparisonType.scala
similarity index 97%
rename from src/main/scala/millfork/compiler/mos/ComparisonType.scala
rename to src/main/scala/millfork/compiler/ComparisonType.scala
index ed894d9c..c2812177 100644
--- a/src/main/scala/millfork/compiler/mos/ComparisonType.scala
+++ b/src/main/scala/millfork/compiler/ComparisonType.scala
@@ -1,4 +1,4 @@
-package millfork.compiler.mos
+package millfork.compiler
 
 /**
   * @author Karol Stasiak
diff --git a/src/main/scala/millfork/compiler/z80/Z80Comparisons.scala b/src/main/scala/millfork/compiler/z80/Z80Comparisons.scala
new file mode 100644
index 00000000..ad509971
--- /dev/null
+++ b/src/main/scala/millfork/compiler/z80/Z80Comparisons.scala
@@ -0,0 +1,38 @@
+package millfork.compiler.z80
+
+import millfork.assembly.z80._
+import millfork.compiler._
+import millfork.node.{Expression, ZRegister}
+
+/**
+  * @author Karol Stasiak
+  */
+object Z80Comparisons {
+
+  import ComparisonType._
+
+  def compile8BitComparison(ctx: CompilationContext, compType: ComparisonType.Value, l: Expression, r: Expression, branches: BranchSpec): List[ZLine] = {
+    compType match {
+      case GreaterUnsigned | LessOrEqualUnsigned | GreaterSigned | LessOrEqualSigned =>
+        return compile8BitComparison(ctx, ComparisonType.flip(compType), r, l, branches)
+      case _ => ()
+    }
+    val calculateFlags =
+      Z80ExpressionCompiler.compileToA(ctx, r) ++
+        List(ZLine.ld8(ZRegister.E, ZRegister.A)) ++
+        Z80ExpressionCompiler.stashDEIfChanged(Z80ExpressionCompiler.compileToA(ctx, l)) ++
+        List(ZLine.register(ZOpcode.CP, ZRegister.E))
+    val jump = (compType, branches) match {
+      case (Equal, BranchIfTrue(label)) => ZLine.jump(label, IfFlagSet(ZFlag.Z))
+      case (Equal, BranchIfFalse(label)) => ZLine.jump(label, IfFlagClear(ZFlag.Z))
+      case (NotEqual, BranchIfTrue(label)) => ZLine.jump(label, IfFlagClear(ZFlag.Z))
+      case (NotEqual, BranchIfFalse(label)) => ZLine.jump(label, IfFlagSet(ZFlag.Z))
+      case (LessUnsigned, BranchIfTrue(label)) => ZLine.jump(label, IfFlagSet(ZFlag.C))
+      case (LessUnsigned, BranchIfFalse(label)) => ZLine.jump(label, IfFlagClear(ZFlag.C))
+      case (GreaterOrEqualUnsigned, BranchIfTrue(label)) => ZLine.jump(label, IfFlagClear(ZFlag.C))
+      case (GreaterOrEqualUnsigned, BranchIfFalse(label)) => ZLine.jump(label, IfFlagSet(ZFlag.C))
+      case _ => ???
+    }
+    calculateFlags :+ jump
+  }
+}
diff --git a/src/main/scala/millfork/compiler/z80/Z80ExpressionCompiler.scala b/src/main/scala/millfork/compiler/z80/Z80ExpressionCompiler.scala
index a536f4cf..a10e9e95 100644
--- a/src/main/scala/millfork/compiler/z80/Z80ExpressionCompiler.scala
+++ b/src/main/scala/millfork/compiler/z80/Z80ExpressionCompiler.scala
@@ -216,22 +216,52 @@ object Z80ExpressionCompiler extends AbstractExpressionCompiler[ZLine] {
                 ???
               case "<" =>
                 val (size, signed) = assertComparison(ctx, params)
-                ???
+                compileTransitiveRelation(ctx, "<", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, if (signed) ComparisonType.LessSigned else ComparisonType.LessUnsigned, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case ">=" =>
                 val (size, signed) = assertComparison(ctx, params)
-                ???
+                compileTransitiveRelation(ctx, ">=", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, if (signed) ComparisonType.GreaterOrEqualSigned else ComparisonType.GreaterOrEqualUnsigned, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case ">" =>
                 val (size, signed) = assertComparison(ctx, params)
-                ???
+                compileTransitiveRelation(ctx, ">", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, if (signed) ComparisonType.GreaterSigned else ComparisonType.GreaterUnsigned, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case "<=" =>
                 val (size, signed) = assertComparison(ctx, params)
-                ???
+                compileTransitiveRelation(ctx, "<=", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, if (signed) ComparisonType.LessOrEqualSigned else ComparisonType.LessOrEqualUnsigned, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case "==" =>
                 val size = params.map(p => getExpressionType(ctx, p).size).max
-                ???
+                compileTransitiveRelation(ctx, "==", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, ComparisonType.Equal, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case "!=" =>
                 val (l, r, size) = assertBinary(ctx, params)
-                ???
+                compileTransitiveRelation(ctx, "!=", params, target, branches) { (l, r) =>
+                  size match {
+                    case 1 => Z80Comparisons.compile8BitComparison(ctx, ComparisonType.NotEqual, l, r, branches)
+                    case _ => ???
+                  }
+                }
               case "+=" =>
                 val (l, r, size) = assertAssignmentLike(ctx, params)
                 size match {
@@ -495,4 +525,39 @@ object Z80ExpressionCompiler extends AbstractExpressionCompiler[ZLine] {
       case SeparateBytesExpression(hi, lo) => ???
     }
   }
+
+  private def compileTransitiveRelation(ctx: CompilationContext,
+                                        operator: String,
+                                        params: List[Expression],
+                                        target: ZExpressionTarget.Value,
+                                        branches: BranchSpec)(binary: (Expression, Expression) => List[ZLine]): List[ZLine] = {
+    params match {
+      case List(l, r) => binary(l, r)
+      case List(_) | Nil =>
+        ErrorReporting.fatal("")
+      case _ =>
+        params.tail.init.foreach { e =>
+          if (ctx.env.eval(e).isEmpty) e match {
+            case VariableExpression(_) =>
+            case LiteralExpression(_, _) =>
+            case IndexedExpression(_, VariableExpression(_)) =>
+            case IndexedExpression(_, LiteralExpression(_, _)) =>
+            case IndexedExpression(_, SumExpression(List(
+            (_, LiteralExpression(_, _)),
+            (false, VariableExpression(_))
+            ), false)) =>
+            case IndexedExpression(_, SumExpression(List(
+            (false, VariableExpression(_)),
+            (_, LiteralExpression(_, _))
+            ), false)) =>
+            case _ =>
+              ErrorReporting.warn("A complex expression may be evaluated multiple times", ctx.options, e.position)
+          }
+        }
+        val conjunction = params.init.zip(params.tail).map {
+          case (l, r) => FunctionCallExpression(operator, List(l, r))
+        }.reduceLeft((a, b) => FunctionCallExpression("&&", List(a, b)))
+        compile(ctx, conjunction, target, branches)
+    }
+  }
 }
diff --git a/src/test/scala/millfork/test/ComparisonSuite.scala b/src/test/scala/millfork/test/ComparisonSuite.scala
index 852d325b..1507c3a4 100644
--- a/src/test/scala/millfork/test/ComparisonSuite.scala
+++ b/src/test/scala/millfork/test/ComparisonSuite.scala
@@ -1,6 +1,7 @@
 package millfork.test
 
-import millfork.test.emu.{EmuBenchmarkRun, EmuSuperOptimizedRun, EmuUltraBenchmarkRun}
+import millfork.CpuFamily
+import millfork.test.emu.{EmuBenchmarkRun, EmuCrossPlatformBenchmarkRun, EmuSuperOptimizedRun, EmuUltraBenchmarkRun}
 import org.scalatest.{FunSuite, Matchers}
 
 /**
@@ -9,7 +10,7 @@ import org.scalatest.{FunSuite, Matchers}
 class ComparisonSuite extends FunSuite with Matchers {
 
   test("Equality and inequality") {
-    EmuBenchmarkRun(
+    EmuCrossPlatformBenchmarkRun(CpuFamily.M6502, CpuFamily.I80)(
       """
         | byte output @$c000
         | void main () {
@@ -27,7 +28,7 @@ class ComparisonSuite extends FunSuite with Matchers {
   }
 
   test("Less") {
-    EmuBenchmarkRun(
+    EmuCrossPlatformBenchmarkRun(CpuFamily.M6502, CpuFamily.I80)(
       """
         | byte output @$c000
         | void main () {
@@ -40,7 +41,7 @@ class ComparisonSuite extends FunSuite with Matchers {
   }
 
   test("Compare to zero") {
-    EmuBenchmarkRun(
+    EmuCrossPlatformBenchmarkRun(CpuFamily.M6502, CpuFamily.I80)(
       """
         | byte output @$c000
         | void main () {