diff --git a/backend/src/core.rs b/backend/src/core.rs
index e69de29..0c17cac 100644
--- a/backend/src/core.rs
+++ b/backend/src/core.rs
@@ -0,0 +1,12 @@
+pub mod cpu;
+pub mod instruction;
+pub mod interpreter;
+pub mod mem;
+pub mod registers;
+
+pub struct Core {}
+
+impl Core {
+    pub fn stop(&mut self) {}
+    pub fn reset(&mut self) {}
+}
diff --git a/backend/src/core/cpu.rs b/backend/src/core/cpu.rs
new file mode 100644
index 0000000..9370a0f
--- /dev/null
+++ b/backend/src/core/cpu.rs
@@ -0,0 +1,27 @@
+use crate::core::{instruction::Instruction, mem::Memory, registers::Registers};
+
+pub enum CpuType {
+    Interpreter,
+    CachedInterpreter,
+    DynamicRecompiler,
+}
+
+pub trait Cpu {
+    fn get_type() -> CpuType;
+    fn get_regs(&mut self) -> &mut Registers;
+    fn fetch(&self, _: &Memory, _: u64) -> Option<Instruction> {
+        None
+    }
+
+    fn fetch_then_advance(&mut self, _: &Memory) -> Option<Instruction> {
+        None
+    }
+    fn execute(&mut self, mem: &Memory) -> Result<u32, String>;
+    fn advance(&mut self) -> bool {
+        false
+    }
+    fn decode(&mut self, instr: Instruction) -> Result<(), String>;
+    fn reset(&mut self);
+    fn should_service_interrupt(&self) -> bool;
+    fn update_compare_interrupt(&mut self);
+}
diff --git a/backend/src/core/instruction.rs b/backend/src/core/instruction.rs
new file mode 100644
index 0000000..c4c1dd2
--- /dev/null
+++ b/backend/src/core/instruction.rs
@@ -0,0 +1,183 @@
+use proc_bitfield::bitfield;
+
+bitfield! {
+    pub struct Instruction(pub u32): Debug, FromStorage, IntoStorage, DerefStorage {
+        pub special: u8 @ 0..6,
+        pub regimm: u8 @ 16..21,
+        pub rt: u8 @ 16..21,
+        pub cop_rt: u8 @ 16..21,
+        pub rs: u8 @ 21..26,
+        pub cop_rs: u8 @ 21..26,
+        pub opcode: u8 @ 26..32,
+        pub imm: u16 @ 0..16,
+        pub target: u32 @ 0..26,
+        pub funct: u8 @ 0..6,
+        pub sa: u8 @ 6..11,
+        pub rd: u8 @ 11..16,
+    }
+}
+
+enum BranchType {
+    Pure,
+    Likely,
+    Link,
+    LinkLikely,
+}
+
+impl Instruction {
+    fn get_branch(self) -> Option<BranchType> {
+        match self.opcode() {
+            Instruction::BEQ | Instruction::BNE | Instruction::BLEZ | Instruction::BGTZ => {
+                Some(BranchType::Pure)
+            }
+            Instruction::BEQL | Instruction::BNEL | Instruction::BLEZL | Instruction::BGTZL => {
+                Some(BranchType::Likely)
+            }
+            Instruction::REGIMM => match self.regimm() {
+                Instruction::BLTZ | Instruction::BGEZ => Some(BranchType::Pure),
+                Instruction::BLTZAL | Instruction::BGEZAL => Some(BranchType::Link),
+                Instruction::BLTZL | Instruction::BGEZL => Some(BranchType::Likely),
+                Instruction::BLTZALL | Instruction::BGEZALL => Some(BranchType::LinkLikely),
+                _ => None,
+            },
+            Instruction::COP1 => {
+                if self.cop_rs() == 8 {
+                    match self.cop_rt() {
+                        0 | 1 => Some(BranchType::Pure),
+                        2 | 3 => Some(BranchType::Likely),
+                        _ => None,
+                    }
+                } else {
+                    None
+                }
+            }
+            _ => None,
+        }
+    }
+
+    const SPECIAL: u8 = 0b000000;
+    const REGIMM: u8 = 0b000001;
+    const J: u8 = 0b000010;
+    const JAL: u8 = 0b000011;
+    const BEQ: u8 = 0b000100;
+    const BNE: u8 = 0b000101;
+    const BLEZ: u8 = 0b000110;
+    const BGTZ: u8 = 0b000111;
+    const ADDI: u8 = 0b001000;
+    const ADDIU: u8 = 0b001001;
+    const SLTI: u8 = 0b001010;
+    const SLTIU: u8 = 0b001011;
+    const ANDI: u8 = 0b001100;
+    const ORI: u8 = 0b001101;
+    const XORI: u8 = 0b001110;
+    const LUI: u8 = 0b001111;
+    const COP0: u8 = 0b010000;
+    const COP1: u8 = 0b010001;
+    const COP2: u8 = 0b010010;
+    const BEQL: u8 = 0b010100;
+    const BNEL: u8 = 0b010101;
+    const BLEZL: u8 = 0b010110;
+    const BGTZL: u8 = 0b010111;
+    const DADDI: u8 = 0b011000;
+    const DADDIU: u8 = 0b011001;
+    const LDL: u8 = 0b011010;
+    const LDR: u8 = 0b011011;
+    const LB: u8 = 0b100000;
+    const LH: u8 = 0b100001;
+    const LWL: u8 = 0b100010;
+    const LW: u8 = 0b100011;
+    const LBU: u8 = 0b100100;
+    const LHU: u8 = 0b100101;
+    const LWR: u8 = 0b100110;
+    const LWU: u8 = 0b100111;
+    const SB: u8 = 0b101000;
+    const SH: u8 = 0b101001;
+    const SWL: u8 = 0b101010;
+    const SW: u8 = 0b101011;
+    const SDL: u8 = 0b101100;
+    const SDR: u8 = 0b101101;
+    const SWR: u8 = 0b101110;
+    const CACHE: u8 = 0b101111;
+    const LL: u8 = 0b110000;
+    const LWC1: u8 = 0b110001;
+    const LWC2: u8 = 0b110010;
+    const LLD: u8 = 0b110100;
+    const LDC1: u8 = 0b110101;
+    const LDC2: u8 = 0b110110;
+    const LD: u8 = 0b110111;
+    const SC: u8 = 0b111000;
+    const SWC1: u8 = 0b111001;
+    const SWC2: u8 = 0b111010;
+    const SCD: u8 = 0b111100;
+    const SDC1: u8 = 0b111101;
+    const SDC2: u8 = 0b111110;
+    const SD: u8 = 0b111111;
+    // special
+    const SLL: u8 = 0b000000;
+    const SRL: u8 = 0b000010;
+    const SRA: u8 = 0b000011;
+    const SLLV: u8 = 0b000100;
+    const SRLV: u8 = 0b000110;
+    const SRAV: u8 = 0b000111;
+    const JR: u8 = 0b001000;
+    const JALR: u8 = 0b001001;
+    const SYSCALL: u8 = 0b001100;
+    const BREAK: u8 = 0b001101;
+    const SYNC: u8 = 0b001111;
+    const MFHI: u8 = 0b010000;
+    const MTHI: u8 = 0b010001;
+    const MFLO: u8 = 0b010010;
+    const MTLO: u8 = 0b010011;
+    const DSLLV: u8 = 0b010100;
+    const DSRLV: u8 = 0b010110;
+    const DSRAV: u8 = 0b010111;
+    const MULT: u8 = 0b011000;
+    const MULTU: u8 = 0b011001;
+    const DIV: u8 = 0b011010;
+    const DIVU: u8 = 0b011011;
+    const DMULT: u8 = 0b011100;
+    const DMULTU: u8 = 0b011101;
+    const DDIV: u8 = 0b011110;
+    const DDIVU: u8 = 0b011111;
+    const ADD: u8 = 0b100000;
+    const ADDU: u8 = 0b100001;
+    const SUB: u8 = 0b100010;
+    const SUBU: u8 = 0b100011;
+    const AND: u8 = 0b100100;
+    const OR: u8 = 0b100101;
+    const XOR: u8 = 0b100110;
+    const NOR: u8 = 0b100111;
+    const SLT: u8 = 0b101010;
+    const SLTU: u8 = 0b101011;
+    const DADD: u8 = 0b101100;
+    const DADDU: u8 = 0b101101;
+    const DSUB: u8 = 0b101110;
+    const DSUBU: u8 = 0b101111;
+    const TGE: u8 = 0b110000;
+    const TGEU: u8 = 0b110001;
+    const TLT: u8 = 0b110010;
+    const TLTU: u8 = 0b110011;
+    const TEQ: u8 = 0b110100;
+    const TNE: u8 = 0b110110;
+    const DSLL: u8 = 0b111000;
+    const DSRL: u8 = 0b111010;
+    const DSRA: u8 = 0b111011;
+    const DSLL32: u8 = 0b111100;
+    const DSRL32: u8 = 0b111110;
+    const DSRA32: u8 = 0b111111;
+    // regimm
+    const BLTZ: u8 = 0b00000;
+    const BGEZ: u8 = 0b00001;
+    const BLTZL: u8 = 0b00010;
+    const BGEZL: u8 = 0b00011;
+    const TGEI: u8 = 0b01000;
+    const TGEIU: u8 = 0b01001;
+    const TLTI: u8 = 0b01010;
+    const TLTIU: u8 = 0b01011;
+    const TEQI: u8 = 0b01100;
+    const TNEI: u8 = 0b01110;
+    const BLTZAL: u8 = 0b10000;
+    const BGEZAL: u8 = 0b10001;
+    const BLTZALL: u8 = 0b10010;
+    const BGEZALL: u8 = 0b10011;
+}
diff --git a/backend/src/core/interpreter.rs b/backend/src/core/interpreter.rs
new file mode 100644
index 0000000..af9aab8
--- /dev/null
+++ b/backend/src/core/interpreter.rs
@@ -0,0 +1,77 @@
+use crate::{
+    core::{
+        cpu::{Cpu, CpuType::*},
+        instruction::Instruction,
+        mem::Memory,
+        registers::Registers,
+    },
+    utils::access::is_address_error,
+};
+
+pub struct Interpreter {
+    regs: Registers,
+    delay_slot: bool,
+    prev_delay_slot: bool,
+}
+
+impl Cpu for Interpreter {
+    fn get_type() -> super::cpu::CpuType {
+        Interpreter
+    }
+
+    fn get_regs(&mut self) -> &mut Registers {
+        &mut self.regs
+    }
+
+    fn should_service_interrupt(&self) -> bool {
+        false
+    }
+
+    fn update_compare_interrupt(&mut self) {
+        todo!("update_compare_interrupt")
+    }
+
+    fn fetch(&self, _mem: &Memory, _vaddr: u64) -> Option<Instruction> {
+        todo!("translate vaddr to paddr and if it fails, throw the exception and return None");
+        // Some(mem.read<u32>(paddr).into())
+    }
+
+    fn fetch_then_advance(&mut self, mem: &Memory) -> Option<Instruction> {
+        self.update_compare_interrupt();
+
+        self.prev_delay_slot = self.delay_slot;
+        self.delay_slot = false;
+
+        if is_address_error(&self.regs, 0b11, self.regs.curr_pc) {
+            todo!("is_address_error ? then throw exception and return None");
+        }
+
+        let instr = self.fetch(mem, self.regs.curr_pc as u64)?;
+
+        if self.should_service_interrupt() {
+            todo!("should_service_interrupt ? then throw exception and return None");
+        }
+
+        self.regs.old_pc = self.regs.curr_pc;
+        self.regs.curr_pc = self.regs.next_pc;
+        self.regs.next_pc += 4;
+
+        Some(instr)
+    }
+
+    fn execute(&mut self, mem: &Memory) -> Result<u32, String> {
+        if let Some(instr) = self.fetch_then_advance(mem) {
+            self.decode(instr)?;
+        }
+
+        Ok(1)
+    }
+
+    fn decode(&mut self, instr: Instruction) -> Result<(), String> {
+        todo!("decode")
+    }
+
+    fn reset(&mut self) {
+        todo!("reset")
+    }
+}
diff --git a/backend/src/core/mem.rs b/backend/src/core/mem.rs
new file mode 100644
index 0000000..d8ca004
--- /dev/null
+++ b/backend/src/core/mem.rs
@@ -0,0 +1 @@
+pub struct Memory {}
diff --git a/backend/src/core/registers.rs b/backend/src/core/registers.rs
new file mode 100644
index 0000000..0771cda
--- /dev/null
+++ b/backend/src/core/registers.rs
@@ -0,0 +1,51 @@
+pub struct Registers {
+    pub gpr: [i64; 32],
+    pub old_pc: i64,
+    pub curr_pc: i64,
+    pub next_pc: i64,
+    pub hi: i64,
+    pub lo: i64,
+    pub constant_regs: u64,
+}
+
+impl Registers {
+    pub fn new() -> Self {
+        Self {
+            gpr: [0; 32],
+            old_pc: 0,
+            curr_pc: 0,
+            next_pc: 0,
+            hi: 0,
+            lo: 0,
+            constant_regs: 1,
+        }
+    }
+
+    pub fn set_pc<T>(&mut self, value: T)
+    where
+        i64: From<T>,
+    {
+        self.old_pc = self.curr_pc;
+        self.curr_pc = value.into();
+        self.next_pc = self.curr_pc + 4;
+    }
+
+    pub fn read<T>(&self, idx: usize) -> T
+    where
+        T: From<i64>,
+    {
+        self.gpr[idx].into()
+    }
+
+    pub fn write<T>(&mut self, idx: usize, value: T)
+    where
+        i64: From<T>,
+    {
+        if idx == 0 {
+            return;
+        }
+
+        self.constant_regs |= 1 << idx;
+        self.gpr[idx] = value.into();
+    }
+}
diff --git a/backend/src/lib.rs b/backend/src/lib.rs
index 8b13789..920371e 100644
--- a/backend/src/lib.rs
+++ b/backend/src/lib.rs
@@ -1 +1,5 @@
+#![allow(dead_code)]
 
+pub mod core;
+pub mod scheduler;
+pub mod utils;
diff --git a/backend/src/utils/access.rs b/backend/src/utils/access.rs
new file mode 100644
index 0000000..1354f71
--- /dev/null
+++ b/backend/src/utils/access.rs
@@ -0,0 +1,6 @@
+use crate::core::registers::Registers;
+
+pub fn is_address_error(_regs: &Registers, mask: u8, vaddr: i64) -> bool {
+    vaddr & mask as i64 != 0
+    // || (!regs.cop0.is64BitAddressing && s32(vaddr) != vaddr)
+}
diff --git a/backend/src/utils/mod.rs b/backend/src/utils/mod.rs
new file mode 100644
index 0000000..207872c
--- /dev/null
+++ b/backend/src/utils/mod.rs
@@ -0,0 +1 @@
+pub mod access;
\ No newline at end of file