diff --git a/crates/cpu/src/unit.rs b/crates/cpu/src/unit.rs
index ce024a4..d7442a3 100644
--- a/crates/cpu/src/unit.rs
+++ b/crates/cpu/src/unit.rs
@@ -387,6 +387,12 @@ impl RenamedMOpFilter for () {
     }
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub struct UnitIO {
+    pub cd: Option<Expr<ClockDomain>>,
+    pub from_execute: Expr<ExecuteToUnitInterface<PhantomConst<CpuConfig>>>,
+}
+
 pub trait UnitTrait:
     'static + Send + Sync + std::fmt::Debug + fayalite::intern::SupportsPtrEqWithTypeId
 {
@@ -395,11 +401,7 @@ pub trait UnitTrait:
     fn ty(&self) -> Self::Type;
     fn unit_kind(&self) -> UnitKind;
     fn module(&self) -> Interned<Module<Self::Type>>;
-    fn cd(&self, this: Expr<Self::Type>) -> Option<Expr<ClockDomain>>;
-    fn from_execute(
-        &self,
-        this: Expr<Self::Type>,
-    ) -> Expr<ExecuteToUnitInterface<PhantomConst<CpuConfig>>>;
+    fn io(&self, this: Expr<Self::Type>) -> UnitIO;
     fn to_dyn(&self) -> DynUnit;
 }
 
@@ -434,15 +436,8 @@ impl UnitTrait for DynUnit {
         self.unit.module()
     }
 
-    fn cd(&self, this: Expr<Self::Type>) -> Option<Expr<ClockDomain>> {
-        self.unit.cd(this)
-    }
-
-    fn from_execute(
-        &self,
-        this: Expr<Self::Type>,
-    ) -> Expr<ExecuteToUnitInterface<PhantomConst<CpuConfig>>> {
-        self.unit.from_execute(this)
+    fn io(&self, this: Expr<Self::Type>) -> UnitIO {
+        self.unit.io(this)
     }
 
     fn to_dyn(&self) -> DynUnit {
@@ -468,15 +463,8 @@ impl<T: UnitTrait + Clone + std::hash::Hash + Eq> UnitTrait for DynUnitWrapper<T
         self.0.module().canonical().intern_sized()
     }
 
-    fn cd(&self, this: Expr<Self::Type>) -> Option<Expr<ClockDomain>> {
-        self.0.cd(Expr::from_bundle(this))
-    }
-
-    fn from_execute(
-        &self,
-        this: Expr<Self::Type>,
-    ) -> Expr<ExecuteToUnitInterface<PhantomConst<CpuConfig>>> {
-        self.0.from_execute(Expr::from_bundle(this))
+    fn io(&self, this: Expr<Self::Type>) -> UnitIO {
+        self.0.io(Expr::from_bundle(this))
     }
 
     fn to_dyn(&self) -> DynUnit {
diff --git a/crates/cpu/src/unit/alu_branch.rs b/crates/cpu/src/unit/alu_branch.rs
index 9ad3f4b..52bd4ab 100644
--- a/crates/cpu/src/unit/alu_branch.rs
+++ b/crates/cpu/src/unit/alu_branch.rs
@@ -18,7 +18,7 @@ use crate::{
         ExecuteToUnitInterface, GlobalState, NextPcPredictorOp, RenamedMOp, UnitCausedCancel,
         UnitFinishCauseCancel, UnitInputsReady, UnitOutputReady,
     },
-    unit::{DynUnit, DynUnitWrapper, RenamedMOpFilter, UnitKind, UnitTrait},
+    unit::{DynUnit, DynUnitWrapper, RenamedMOpFilter, UnitIO, UnitKind, UnitTrait},
 };
 use fayalite::{
     expr::CastToImpl,
@@ -1613,15 +1613,11 @@ impl UnitTrait for AluBranch {
         self.module
     }
 
-    fn cd(&self, _this: Expr<Self::Type>) -> Option<Expr<ClockDomain>> {
-        None
-    }
-
-    fn from_execute(
-        &self,
-        this: Expr<Self::Type>,
-    ) -> Expr<ExecuteToUnitInterface<PhantomConst<CpuConfig>>> {
-        this.from_execute
+    fn io(&self, this: Expr<Self::Type>) -> UnitIO {
+        UnitIO {
+            cd: None,
+            from_execute: this.from_execute,
+        }
     }
 
     fn to_dyn(&self) -> DynUnit {
diff --git a/crates/cpu/tests/units_formal.rs b/crates/cpu/tests/units_formal.rs
index 47ad415..fa3397d 100644
--- a/crates/cpu/tests/units_formal.rs
+++ b/crates/cpu/tests/units_formal.rs
@@ -14,7 +14,7 @@ use cpu::{
         DecodeAndRunSingleInsnInput, DecodeAndRunSingleInsnOutput, DecodeOneInsnInput,
         DecodeOneInsnMaxMOpCount, decode_and_run_single_insn,
     },
-    unit::{RenamedMOpFilter, UnitKind, UnitMOp, UnitTrait},
+    unit::{RenamedMOpFilter, UnitIO, UnitKind, UnitMOp, UnitTrait},
     util::array_vec::ArrayVec,
 };
 use fayalite::{
@@ -91,11 +91,15 @@ fn formal_harness(
             dyn_unit.module(),
             SourceLocation::caller(),
         );
+        let UnitIO {
+            cd: unit_cd,
+            from_execute: unit_from_execute,
+        } = dyn_unit.io(unit);
         connect(
-            dyn_unit.from_execute(unit),
+            unit_from_execute,
             ExecuteToUnitInterfaces::unit_fields(decode_and_run.to_units)[unit_index],
         );
-        if let Some(unit_cd) = dyn_unit.cd(unit) {
+        if let Some(unit_cd) = unit_cd {
             connect(unit_cd, cd);
         }
     }