Fixed borrow issues

src/components/cpu/intel_4004.rs

@@ -26,7 +26,7 @@ pub struct Intel4004 {
     accumulator: u8,
     carry: bool,
     index_registers: [u8; 16],
-    program_counter: U12,
+    pub(crate) program_counter: U12,
     stack: [U12; 3],
     stack_pointer: u8,
     cycle_count: u64,

src/components/cpu/mos_6502.rs

@@ -101,7 +101,7 @@ impl MOS6502 {
         }
     }
 
-    fn read_data_bus(&self) -> u8 {
+    fn _read_data_bus(&self) -> u8 {
         let mut data = 0;
 
         for i in 0..8 {

src/components/memory/intel_4001.rs

@@ -352,11 +352,11 @@ impl Intel4001 {
         self.input_latch
     }
 
-    pub fn get_io_mode(&self) -> IoMode {
+    fn get_io_mode(&self) -> IoMode {
         self.io_mode
     }
 
-    pub fn set_io_mode(&mut self, mode: IoMode) {
+    fn set_io_mode(&mut self, mode: IoMode) {
         self.io_mode = mode;
         match mode {
             IoMode::Input => self.tri_state_io_pins(),