diff --git a/lib/waterfoul/cpu.rb b/lib/waterfoul/cpu.rb
index ac263e6..2d30f0b 100644
--- a/lib/waterfoul/cpu.rb
+++ b/lib/waterfoul/cpu.rb
@@ -125,7 +125,7 @@ module Waterfoul
       # master disable interrupts
       @ime = false
       push_onto_stack @pc
-      if_reg = $mmu.read_byte 0xFF0F
+      if_reg = $mmu.read_memory_byte 0xFF0F
       case interrupt
       when Interrupt::INTERRUPT_VBLANK
         @pc = 0x40
diff --git a/lib/waterfoul/instructions/misc.rb b/lib/waterfoul/instructions/misc.rb
index f211195..0f4601c 100644
--- a/lib/waterfoul/instructions/misc.rb
+++ b/lib/waterfoul/instructions/misc.rb
@@ -19,7 +19,7 @@ module Waterfoul
       # Halt CPU & LCD display until button pressed.
       # @flags - - - -
       def halt
-        @pre_halt_interrupt = $mmu.read_byte(0xFF0F)
+        @pre_halt_interrupt = $mmu.read_memory_byte(0xFF0F)
         @halt = true
       end
 
diff --git a/lib/waterfoul/interrupt.rb b/lib/waterfoul/interrupt.rb
index 520dc16..8a2cf4c 100644
--- a/lib/waterfoul/interrupt.rb
+++ b/lib/waterfoul/interrupt.rb
@@ -14,13 +14,13 @@ module Waterfoul
 
     #
     def self.request_interrupt(interrupt)
-      if_reg = $mmu.read_byte IF_REG_MEM_LOC
+      if_reg = $mmu.read_memory_byte IF_REG_MEM_LOC
       $mmu.write_byte IF_REG_MEM_LOC, (if_reg | interrupt)
     end
 
     def self.pending_interrupt
-      ie_reg = $mmu.read_byte IE_REG_MEM_LOC
-      if_reg = $mmu.read_byte IF_REG_MEM_LOC
+      ie_reg = $mmu.read_memory_byte IE_REG_MEM_LOC
+      if_reg = $mmu.read_memory_byte IF_REG_MEM_LOC
       pending_interrupts = if_reg & ie_reg
 
       if pending_interrupts & INTERRUPT_VBLANK == INTERRUPT_VBLANK
diff --git a/lib/waterfoul/io/lcd_control.rb b/lib/waterfoul/io/lcd_control.rb
index d58b852..ac318d0 100644
--- a/lib/waterfoul/io/lcd_control.rb
+++ b/lib/waterfoul/io/lcd_control.rb
@@ -44,7 +44,7 @@ module Waterfoul
         private
 
         def lcdc
-          $mmu.read_byte LCDC_MEM_LOC
+          $mmu.read_memory_byte LCDC_MEM_LOC
         end
       end
     end
diff --git a/lib/waterfoul/ppu.rb b/lib/waterfoul/ppu.rb
index cca7638..f018b81 100644
--- a/lib/waterfoul/ppu.rb
+++ b/lib/waterfoul/ppu.rb
@@ -128,7 +128,7 @@ module Waterfoul
     end
 
     def update_stat_mode
-      stat = $mmu.read_byte 0xFF41
+      stat = $mmu.read_memory_byte 0xFF41
       new_stat = (stat & 0xFC) | (@mode & 0x3)
       $mmu.write_byte 0xFF41, new_stat
     end
@@ -140,8 +140,8 @@ module Waterfoul
       # if the LCDC window enable bit flag is not set
       return if @window_line > 143 || !IO::LCDControl.window_enabled?
 
-      window_pos_x = $mmu.read_byte(0xFF4B) - 7
-      window_pos_y = $mmu.read_byte(0xFF4A)
+      window_pos_x = $mmu.read_memory_byte(0xFF4B) - 7
+      window_pos_y = $mmu.read_memory_byte(0xFF4A)
 
       # don't render if the window is outside the bounds of the screen
       return if window_pos_x > 159 || window_pos_y > 143 || window_pos_y > line
@@ -206,14 +206,14 @@ module Waterfoul
       39.downto(0) do |sprite|
         sprite_offset = sprite * 4
 
-        sprite_y = $mmu.read_byte(0xFE00 + sprite_offset) - 16
+        sprite_y = $mmu.read_memory_byte(0xFE00 + sprite_offset) - 16
         next if sprite_y > line || (sprite_y + sprite_size) <= line
 
-        sprite_x = $mmu.read_byte(0xFE00 + sprite_offset + 1) - 8
+        sprite_x = $mmu.read_memory_byte(0xFE00 + sprite_offset + 1) - 8
         next if sprite_x < -7 || sprite_x >= Screen::SCREEN_WIDTH
 
-        sprite_tile_offset = ($mmu.read_byte(0xFE00 + sprite_offset + 2) & (sprite_size == 16 ? 0xFE : 0xFF)) * 16
-        sprite_flags = $mmu.read_byte(0xFE00 + sprite_offset + 3)
+        sprite_tile_offset = ($mmu.read_memory_byte(0xFE00 + sprite_offset + 2) & (sprite_size == 16 ? 0xFE : 0xFF)) * 16
+        sprite_flags = $mmu.read_memory_byte(0xFE00 + sprite_offset + 3)
         x_flip = sprite_flags & 0x20 == 0x20 ? true : false
         y_flip = sprite_flags & 0x40 == 0x40 ? true : false
         #above_bg = sprite_flags & 0x80 == 0x80 ? true : false
@@ -269,9 +269,9 @@ module Waterfoul
         tiles_select = IO::LCDControl.bg_tile_select
         map_select = IO::LCDControl.bg_map_select
         # x pixel offset
-        scx = $mmu.read_byte 0xFF43
+        scx = $mmu.read_memory_byte 0xFF43
         # y pixel offset
-        scy = $mmu.read_byte 0xFF42
+        scy = $mmu.read_memory_byte 0xFF42
         # line with y offset
         line_adjusted = (line + scy) & 0xFF
         # get position of tile row to read
@@ -332,8 +332,8 @@ module Waterfoul
 
     def compare_lylc
       if IO::LCDControl.screen_enabled?
-        lyc = $mmu.read_byte 0xFF45
-        stat = $mmu.read_byte 0xFF41
+        lyc = $mmu.read_memory_byte 0xFF45
+        stat = $mmu.read_memory_byte 0xFF41
 
         if lyc == current_line
           stat = stat | 0x4
@@ -345,7 +345,7 @@ module Waterfoul
     end
 
     def current_line
-      $mmu.read_byte LCDC_Y_COORDINATE_MEM_LOC
+      $mmu.read_memory_byte LCDC_Y_COORDINATE_MEM_LOC
     end
 
     def reset_current_line
diff --git a/lib/waterfoul/timer.rb b/lib/waterfoul/timer.rb
index dff3ab9..88c1b4d 100644
--- a/lib/waterfoul/timer.rb
+++ b/lib/waterfoul/timer.rb
@@ -27,9 +27,9 @@ module Waterfoul
     end
 
     def inc_tima_register
-      tima = $mmu.read_byte 0xFF05
+      tima = $mmu.read_memory_byte 0xFF05
       if tima == 0xFF
-        tima = $mmu.read_byte 0xFF06
+        tima = $mmu.read_memory_byte 0xFF06
         Interrupt.request_interrupt(Interrupt::INTERRUPT_TIMER)
       else
         tima += 1
@@ -39,7 +39,7 @@ module Waterfoul
     end
 
     def inc_div_register
-      div = $mmu.read_byte 0xFF04
+      div = $mmu.read_memory_byte 0xFF04
       div = (div + 1) & 0xFF
       $mmu.write_byte 0xFF04, div, hardware_operation: true
       @div_cycles -= DIV_INC_TIME
@@ -52,7 +52,7 @@ module Waterfoul
     end
 
     def update
-      @register = $mmu.read_byte 0xFF07
+      @register = $mmu.read_memory_byte 0xFF07
     end
 
     def running?