diff --git a/omreader/src/Main.scala b/omreader/src/Main.scala
index bce1341d5e..0f36cdae7f 100644
--- a/omreader/src/Main.scala
+++ b/omreader/src/Main.scala
@@ -3,8 +3,11 @@
 
 package org.chipsalliance.t1.omreader
 
+import java.io.BufferedInputStream
+
 import mainargs._
 import chisel3.panamalib.option._
+import chisel3.panamaom._
 import chisel3.panamaconverter.PanamaCIRCTConverter
 import org.chipsalliance.t1.omreaderlib
 
@@ -16,11 +19,20 @@ object Main {
 
   @main
   def run(
-    @arg(name = "mlirbc-file") mlirbc: os.Path,
+    @arg(name = "mlirbc-file") mlirbcFile: Option[os.Path],
+    @arg(name = "class-name") className: String,
+    @arg(name = "dump") dump: Flag,
+    @arg(name = "eval") eval: Option[String],
   ) = {
     omreaderlib.Hello()
 
-    val cvt = PanamaCIRCTConverter.newWithMlirBc(os.read.bytes(mlirbc))
+    val inputs = mlirbcFile match {
+      case Some(path) => os.read.bytes(path)
+      case None =>
+        val stdin = new BufferedInputStream(System.in)
+        Stream.continually(stdin.read).takeWhile(_ != -1).map(_.toByte).toArray
+    }
+    val cvt = PanamaCIRCTConverter.newWithMlirBc(inputs)
 
     val pm = cvt.passManager()
     assert(pm.populatePreprocessTransforms())
@@ -33,9 +45,30 @@ object Main {
 
     val om = cvt.om()
     val evaluator = om.evaluator()
-    val t1 = evaluator.instantiate("T1_1_Class", Seq(om.newBasePathEmpty))
-    t1.foreachField((name, value) => println(s".$name => { ${value.toString} }"))
+    val entry = evaluator.instantiate(className, Seq(om.newBasePathEmpty))
+
+    if (dump.value) {
+      entry.foreachField((name, value) => println(s".$name => $value"))
+    }
+    else if (eval.nonEmpty) {
+      val result = SimpleInputEval(entry, eval.get)
+      println(result)
+    }
   }
 
   def main(args: Array[String]): Unit = ParserForMethods(this).runOrExit(args)
 }
+
+object SimpleInputEval {
+  def apply(entry: PanamaCIRCTOMEvaluatorValue, input: String): PanamaCIRCTOMEvaluatorValue = {
+    input.split("\\.").foldLeft(entry) {
+      case (obj, field) =>
+        if (field.forall(_.isDigit)) {
+          obj.asInstanceOf[PanamaCIRCTOMEvaluatorValueList].getElement(field.toLong)
+        } else {
+          obj.asInstanceOf[PanamaCIRCTOMEvaluatorValueObject].field(field)
+        }
+    }
+  }
+}
+