diff --git a/ceno_emul/src/addr.rs b/ceno_emul/src/addr.rs
index dfd9056b7..78b01563e 100644
--- a/ceno_emul/src/addr.rs
+++ b/ceno_emul/src/addr.rs
@@ -197,17 +197,17 @@ impl ops::AddAssign<u32> for ByteAddr {
 }
 
 pub trait IterAddresses {
-    fn iter_addresses(&self) -> impl Iterator<Item = Addr>;
+    fn iter_addresses(&self) -> impl ExactSizeIterator<Item = Addr>;
 }
 
 impl IterAddresses for Range<Addr> {
-    fn iter_addresses(&self) -> impl Iterator<Item = Addr> {
+    fn iter_addresses(&self) -> impl ExactSizeIterator<Item = Addr> {
         self.clone().step_by(WORD_SIZE)
     }
 }
 
 impl<'a, T: GetAddr> IterAddresses for &'a [T] {
-    fn iter_addresses(&self) -> impl Iterator<Item = Addr> {
+    fn iter_addresses(&self) -> impl ExactSizeIterator<Item = Addr> {
         self.iter().map(T::get_addr)
     }
 }
diff --git a/ceno_emul/src/platform.rs b/ceno_emul/src/platform.rs
index fb11d166d..b0fa0afe7 100644
--- a/ceno_emul/src/platform.rs
+++ b/ceno_emul/src/platform.rs
@@ -12,6 +12,7 @@ pub struct Platform {
     pub rom: Range<Addr>,
     pub ram: Range<Addr>,
     pub public_io: Range<Addr>,
+    pub private_io: Range<Addr>,
     pub stack_top: Addr,
     /// If true, ecall instructions are no-op instead of trap. Testing only.
     pub unsafe_ecall_nop: bool,
@@ -21,6 +22,7 @@ pub const CENO_PLATFORM: Platform = Platform {
     rom: 0x2000_0000..0x3000_0000,
     ram: 0x8000_0000..0xFFFF_0000,
     public_io: 0x3000_1000..0x3000_2000,
+    private_io: 0x4000_0000..0x5000_0000,
     stack_top: 0xC0000000,
     unsafe_ecall_nop: false,
 };
@@ -40,6 +42,10 @@ impl Platform {
         self.public_io.contains(&addr)
     }
 
+    pub fn is_priv_io(&self, addr: Addr) -> bool {
+        self.private_io.contains(&addr)
+    }
+
     /// Virtual address of a register.
     pub const fn register_vma(index: RegIdx) -> Addr {
         // Register VMAs are aligned, cannot be confused with indices, and readable in hex.
@@ -60,7 +66,7 @@ impl Platform {
     // Permissions.
 
     pub fn can_read(&self, addr: Addr) -> bool {
-        self.is_rom(addr) || self.is_ram(addr) || self.is_pub_io(addr)
+        self.is_rom(addr) || self.is_ram(addr) || self.is_pub_io(addr) || self.is_priv_io(addr)
     }
 
     pub fn can_write(&self, addr: Addr) -> bool {
diff --git a/ceno_zkvm/examples/riscv_opcodes.rs b/ceno_zkvm/examples/riscv_opcodes.rs
index 0711bd58f..67a314683 100644
--- a/ceno_zkvm/examples/riscv_opcodes.rs
+++ b/ceno_zkvm/examples/riscv_opcodes.rs
@@ -275,6 +275,7 @@ fn main() {
                 &reg_final,
                 &mem_final,
                 &public_io_final,
+                &[],
             )
             .unwrap();
 
diff --git a/ceno_zkvm/src/bin/e2e.rs b/ceno_zkvm/src/bin/e2e.rs
index a4a2b6087..9da848b7e 100644
--- a/ceno_zkvm/src/bin/e2e.rs
+++ b/ceno_zkvm/src/bin/e2e.rs
@@ -1,6 +1,6 @@
 use ceno_emul::{
-    ByteAddr, CENO_PLATFORM, EmuContext, InsnKind::EANY, Platform, StepRecord, Tracer, VMState,
-    WORD_SIZE, WordAddr,
+    ByteAddr, CENO_PLATFORM, EmuContext, InsnKind::EANY, IterAddresses, Platform, StepRecord,
+    Tracer, VMState, WORD_SIZE, Word, WordAddr,
 };
 use ceno_zkvm::{
     instructions::riscv::{DummyExtraConfig, MemPadder, MmuConfig, Rv32imConfig},
@@ -19,7 +19,9 @@ use itertools::{Itertools, MinMaxResult, chain, enumerate};
 use mpcs::{Basefold, BasefoldRSParams, PolynomialCommitmentScheme};
 use std::{
     collections::{HashMap, HashSet},
-    fs, panic,
+    fs,
+    iter::zip,
+    panic,
     time::Instant,
 };
 use tracing::level_filters::LevelFilter;
@@ -41,6 +43,11 @@ struct Args {
     /// The preset configuration to use.
     #[arg(short, long, value_enum, default_value_t = Preset::Ceno)]
     platform: Preset,
+
+    /// The private input or hints. This is a raw file mounted as a memory segment.
+    /// Zero-padded to the next power-of-two size.
+    #[arg(long)]
+    private_input: Option<String>,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, ValueEnum)]
@@ -94,6 +101,17 @@ fn main() {
     let elf_bytes = fs::read(&args.elf).expect("read elf file");
     let mut vm = VMState::new_from_elf(platform.clone(), &elf_bytes).unwrap();
 
+    tracing::info!("Loading private input file: {:?}", args.private_input);
+    let priv_io = memory_from_file(&args.private_input);
+    assert!(
+        priv_io.len() <= platform.private_io.iter_addresses().len(),
+        "private input must fit in {} bytes",
+        platform.private_io.len()
+    );
+    for (addr, value) in zip(platform.private_io.iter_addresses(), &priv_io) {
+        vm.init_memory(addr.into(), *value);
+    }
+
     // keygen
     let pcs_param = Pcs::setup(1 << MAX_NUM_VARIABLES).expect("Basefold PCS setup");
     let (pp, vp) = Pcs::trim(pcs_param, 1 << MAX_NUM_VARIABLES).expect("Basefold trim");
@@ -249,6 +267,14 @@ fn main() {
         .map(|rec| *final_access.get(&rec.addr.into()).unwrap_or(&0))
         .collect_vec();
 
+    let priv_io_final = zip(platform.private_io.iter_addresses(), &priv_io)
+        .map(|(addr, &value)| MemFinalRecord {
+            addr,
+            value,
+            cycle: *final_access.get(&addr.into()).unwrap_or(&0),
+        })
+        .collect_vec();
+
     // assign table circuits
     config
         .assign_table_circuit(&zkvm_cs, &mut zkvm_witness)
@@ -260,6 +286,7 @@ fn main() {
             &reg_final,
             &mem_final,
             &io_final,
+            &priv_io_final,
         )
         .unwrap();
     // assign program circuit
@@ -332,6 +359,18 @@ fn main() {
     };
 }
 
+fn memory_from_file(path: &Option<String>) -> Vec<u32> {
+    path.as_ref()
+        .map(|path| {
+            let mut buf = fs::read(path).expect("could not read file");
+            buf.resize(buf.len().next_multiple_of(WORD_SIZE), 0);
+            buf.chunks_exact(WORD_SIZE)
+                .map(|word| Word::from_le_bytes(word.try_into().unwrap()))
+                .collect_vec()
+        })
+        .unwrap_or_default()
+}
+
 fn debug_memory_ranges(vm: &VMState, mem_final: &[MemFinalRecord]) {
     let accessed_addrs = vm
         .tracer()
diff --git a/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs b/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
index 66eafd891..fe1722728 100644
--- a/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
+++ b/ceno_zkvm/src/instructions/riscv/rv32im/mmu.rs
@@ -8,8 +8,8 @@ use crate::{
     error::ZKVMError,
     structs::{ProgramParams, ZKVMConstraintSystem, ZKVMFixedTraces, ZKVMWitnesses},
     tables::{
-        MemFinalRecord, MemInitRecord, NonVolatileTable, PubIOCircuit, PubIOTable, RegTable,
-        RegTableCircuit, StaticMemCircuit, StaticMemTable, TableCircuit,
+        MemFinalRecord, MemInitRecord, NonVolatileTable, PrivateIOCircuit, PubIOCircuit,
+        PubIOTable, RegTable, RegTableCircuit, StaticMemCircuit, StaticMemTable, TableCircuit,
     },
 };
 
@@ -20,6 +20,8 @@ pub struct MmuConfig<E: ExtensionField> {
     pub static_mem_config: <StaticMemCircuit<E> as TableCircuit<E>>::TableConfig,
     /// Initialization of public IO.
     pub public_io_config: <PubIOCircuit<E> as TableCircuit<E>>::TableConfig,
+    /// Initialization of private IO.
+    pub private_io_config: <PrivateIOCircuit<E> as TableCircuit<E>>::TableConfig,
     pub params: ProgramParams,
 }
 
@@ -30,11 +32,13 @@ impl<E: ExtensionField> MmuConfig<E> {
         let static_mem_config = cs.register_table_circuit::<StaticMemCircuit<E>>();
 
         let public_io_config = cs.register_table_circuit::<PubIOCircuit<E>>();
+        let private_io_config = cs.register_table_circuit::<PrivateIOCircuit<E>>();
 
         Self {
             reg_config,
             static_mem_config,
             public_io_config,
+            private_io_config,
             params: cs.params.clone(),
         }
     }
@@ -48,7 +52,13 @@ impl<E: ExtensionField> MmuConfig<E> {
         io_addrs: &[Addr],
     ) {
         assert!(
-            chain!(static_mem_init.iter_addresses(), io_addrs.iter_addresses()).all_unique(),
+            chain!(
+                static_mem_init.iter_addresses(),
+                io_addrs.iter_addresses(),
+                // TODO: optimize with min_max and Range.
+                self.params.platform.private_io.iter_addresses(),
+            )
+            .all_unique(),
             "memory addresses must be unique"
         );
 
@@ -61,6 +71,7 @@ impl<E: ExtensionField> MmuConfig<E> {
         );
 
         fixed.register_table_circuit::<PubIOCircuit<E>>(cs, &self.public_io_config, io_addrs);
+        fixed.register_table_circuit::<PrivateIOCircuit<E>>(cs, &self.private_io_config, &());
     }
 
     pub fn assign_table_circuit(
@@ -70,6 +81,7 @@ impl<E: ExtensionField> MmuConfig<E> {
         reg_final: &[MemFinalRecord],
         static_mem_final: &[MemFinalRecord],
         io_cycles: &[Cycle],
+        private_io_final: &[MemFinalRecord],
     ) -> Result<(), ZKVMError> {
         witness.assign_table_circuit::<RegTableCircuit<E>>(cs, &self.reg_config, reg_final)?;
 
@@ -81,6 +93,12 @@ impl<E: ExtensionField> MmuConfig<E> {
 
         witness.assign_table_circuit::<PubIOCircuit<E>>(cs, &self.public_io_config, io_cycles)?;
 
+        witness.assign_table_circuit::<PrivateIOCircuit<E>>(
+            cs,
+            &self.private_io_config,
+            private_io_final,
+        )?;
+
         Ok(())
     }
 
diff --git a/ceno_zkvm/src/tables/ram.rs b/ceno_zkvm/src/tables/ram.rs
index 88e968e69..f6fcb0282 100644
--- a/ceno_zkvm/src/tables/ram.rs
+++ b/ceno_zkvm/src/tables/ram.rs
@@ -34,25 +34,25 @@ impl DynVolatileRamTable for DynMemTable {
 pub type DynMemCircuit<E> = DynVolatileRamCircuit<E, DynMemTable>;
 
 #[derive(Clone)]
-pub struct PrivateMemTable;
-impl DynVolatileRamTable for PrivateMemTable {
+pub struct PrivateIOTable;
+impl DynVolatileRamTable for PrivateIOTable {
     const RAM_TYPE: RAMType = RAMType::Memory;
     const V_LIMBS: usize = 1; // See `MemoryExpr`.
     const ZERO_INIT: bool = false;
 
     fn offset_addr(params: &ProgramParams) -> Addr {
-        params.platform.ram.start
+        params.platform.private_io.start
     }
 
     fn end_addr(params: &ProgramParams) -> Addr {
-        params.platform.ram.end
+        params.platform.private_io.end
     }
 
     fn name() -> &'static str {
-        "PrivateMemTable"
+        "PrivateIOTable"
     }
 }
-pub type PrivateMemCircuit<E> = DynVolatileRamCircuit<E, PrivateMemTable>;
+pub type PrivateIOCircuit<E> = DynVolatileRamCircuit<E, PrivateIOTable>;
 
 /// RegTable, fix size without offset
 #[derive(Clone)]
diff --git a/ceno_zkvm/src/tables/ram/ram_circuit.rs b/ceno_zkvm/src/tables/ram/ram_circuit.rs
index 584489781..234ff7799 100644
--- a/ceno_zkvm/src/tables/ram/ram_circuit.rs
+++ b/ceno_zkvm/src/tables/ram/ram_circuit.rs
@@ -189,7 +189,7 @@ impl<E: ExtensionField, DVRAM: DynVolatileRamTable + Send + Sync + Clone> TableC
     type WitnessInput = [MemFinalRecord];
 
     fn name() -> String {
-        format!("RAM_{:?}", DVRAM::RAM_TYPE)
+        format!("RAM_{:?}_{}", DVRAM::RAM_TYPE, DVRAM::name())
     }
 
     fn construct_circuit(cb: &mut CircuitBuilder<E>) -> Result<Self::TableConfig, ZKVMError> {
diff --git a/ceno_zkvm/src/tables/ram/ram_impl.rs b/ceno_zkvm/src/tables/ram/ram_impl.rs
index d293e5d83..2f16c6bff 100644
--- a/ceno_zkvm/src/tables/ram/ram_impl.rs
+++ b/ceno_zkvm/src/tables/ram/ram_impl.rs
@@ -369,15 +369,17 @@ impl<DVRAM: DynVolatileRamTable + Send + Sync + Clone> DynVolatileRamTableConfig
     ) -> Result<RowMajorMatrix<F>, ZKVMError> {
         assert!(final_mem.len() <= DVRAM::max_len(&self.params));
         assert!(DVRAM::max_len(&self.params).is_power_of_two());
-        let mut final_table =
-            RowMajorMatrix::<F>::new(final_mem.len().next_power_of_two(), num_witness);
+        let mut final_table = RowMajorMatrix::<F>::new(final_mem.len(), num_witness);
 
         final_table
             .par_iter_mut()
             .with_min_len(MIN_PAR_SIZE)
             .zip(final_mem.into_par_iter())
-            .for_each(|(row, rec)| {
+            .enumerate()
+            .for_each(|(i, (row, rec))| {
+                assert_eq!(rec.addr, DVRAM::addr(&self.params, i));
                 set_val!(row, self.addr, rec.addr as u64);
+
                 if self.final_v.len() == 1 {
                     // Assign value directly.
                     set_val!(row, self.final_v[0], rec.value as u64);