diff --git a/src/cpu.rs b/src/cpu.rs
index 6bd252a..801980b 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -112,9 +112,13 @@ impl Cpu {
                 instruction_pointer_offset += 4; // increment past 32 bit immediate
                 value
             }
-            Operand::ImmediatePtr => {
+            Operand::ImmediatePtr(size) => {
                 let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
-                let value = self.bus.memory.read_32(pointer);
+                let value = match size {
+                    Size::Byte => self.bus.memory.read_8(pointer) as u32,
+                    Size::Half => self.bus.memory.read_16(pointer) as u32,
+                    Size::Word => self.bus.memory.read_32(pointer),
+                };
                 instruction_pointer_offset += 4; // increment past 32 bit pointer
                 value
             }
@@ -359,7 +363,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -458,7 +462,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -557,7 +561,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -656,7 +660,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -755,7 +759,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -848,7 +852,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -944,7 +948,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1037,7 +1041,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1128,7 +1132,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1218,7 +1222,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1308,7 +1312,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1398,7 +1402,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1494,7 +1498,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1593,7 +1597,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1692,7 +1696,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1791,7 +1795,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1890,7 +1894,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -1978,7 +1982,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2059,7 +2063,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2140,7 +2144,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2228,7 +2232,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2306,7 +2310,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2450,7 +2454,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.relative_to_absolute(self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset));
                         if should_run {
                             self.bus.memory.write_32(pointer, self.relative_to_absolute(source_value));
@@ -2537,7 +2541,7 @@ impl Cpu {
                         }
                         instruction_pointer_offset += 1; // increment past 8 bit register number
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         match size {
                             Size::Byte => {
@@ -2608,7 +2612,7 @@ impl Cpu {
                             self.bus.memory.write_32(pointer, value);
                         }
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         let value = self.bus.read_io(source_value);
                         instruction_pointer_offset += 4; // increment past 32 bit pointer
@@ -2639,7 +2643,7 @@ impl Cpu {
                             self.bus.write_io(self.bus.memory.read_32(pointer), source_value);
                         }
                     }
-                    Operand::ImmediatePtr => {
+                    Operand::ImmediatePtr(_) => {
                         let pointer = self.bus.memory.read_32(self.instruction_pointer + instruction_pointer_offset);
                         instruction_pointer_offset += 4; // increment past 32 bit pointer
                         if should_run {
@@ -2680,10 +2684,10 @@ enum Operand {
     Immediate8,
     Immediate16,
     Immediate32,
-    ImmediatePtr,
+    ImmediatePtr(Size),
 }
 
-#[derive(Debug)]
+#[derive(Copy, Clone, Debug)]
 enum Size {
     Byte,
     Half,
@@ -2775,13 +2779,13 @@ impl Instruction {
                 Size::Half => Operand::Immediate16,
                 Size::Word => Operand::Immediate32,
             },
-            0x03 => Operand::ImmediatePtr,
+            0x03 => Operand::ImmediatePtr(size),
             _ => return None,
         };
         let destination = match (((half & 0x000F) >> 2) as u8) & 0b00000011 {
             0x00 => Operand::Register,
             0x01 => Operand::RegisterPtr,
-            0x02 => Operand::ImmediatePtr,
+            0x02 => Operand::ImmediatePtr(size),
             _ => return None,
         };
         let condition = match (half & 0x00F0) as u8 {
diff --git a/src/main.rs b/src/main.rs
index 92ddeb3..1527512 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -66,25 +66,21 @@ fn main() {
     let mouse = Arc::new(Mutex::new(Mouse::new()));
 
     // 32 MiB of shared memory
-    // plus 3 bytes at the end to allow for reading the last byte of memory as an immediate pointer
-    // Operand::ImmediatePtr always reads 4 bytes
-    let shared_memory = Arc::new(Mutex::new(vec![0u8; 0x02000003]));
+    let shared_memory = Arc::new(Mutex::new(vec![0u8; 0x02000000]));
 
     let mut cpu = {
         // 32 MiB of fast memory
-        // plus 3 extra bytes at the end to allow for reading the last byte of memory as an immediate pointer
-        // Operand::ImmediatePtr always reads 4 bytes
-        let cpu_fast_memory = vec![0; 0x02000003];
+        let cpu_fast_memory = vec![0; 0x02000000];
         let cpu_shared_memory = Arc::clone(&shared_memory);
         let cpu_overlays = Arc::clone(&display.overlays);
         let cpu_read_only_memory = read_rom();
 
-        let fast_size = cpu_fast_memory.len() - 3;
+        let fast_size = cpu_fast_memory.len();
         let fast_bottom_address = 0x00000000;
         let fast_top_address = fast_bottom_address + fast_size - 1;
         println!("Fast:   {:.2}MB mapped at {:#010X}-{:#010X}", fast_size / 1048576, fast_bottom_address, fast_top_address);
 
-        let shared_size = { cpu_shared_memory.lock().unwrap().len() - 3 };
+        let shared_size = { cpu_shared_memory.lock().unwrap().len() };
         let shared_bottom_address = 0x80000000;
         let shared_top_address = shared_bottom_address + shared_size - 1;
         println!("Shared: {:.2}MB mapped at {:#010X}-{:#010X}", shared_size / 1048576, shared_bottom_address, shared_top_address);
diff --git a/src/memory.rs b/src/memory.rs
index a9ce675..35a5ff6 100644
--- a/src/memory.rs
+++ b/src/memory.rs
@@ -19,9 +19,9 @@ pub struct Memory {
 impl Memory {
     pub fn new(fast_memory: Vec<u8>, shared_memory: Arc<Mutex<Vec<u8>>>, overlays: Arc<Mutex<Vec<Overlay>>>, rom: Vec<u8>) -> Self {
         // 3 extra bytes at the end to allow for reading the last byte of memory as an immediate pointer
-        let shared_memory_size = { shared_memory.lock().unwrap().len() - 3 };
+        let shared_memory_size = { shared_memory.lock().unwrap().len() };
         Memory {
-            fast_memory_size: fast_memory.len() - 3,
+            fast_memory_size: fast_memory.len(),
             fast_memory,
             shared_memory_size,
             shared_memory,