diff --git a/.gitignore b/.gitignore
index ce5bd54..aee1c75 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,8 @@ Doxyfile
 !test/blargg_instr_test-v5/rom_singles
 !test/**/*.nes
 !test/**/*.log
+!test/**/*.gz
+!test/sources.txt
 
 # SDL files
 lib/SDL2/docs
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a9e44e5..8fe6c16 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -64,6 +64,14 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
     target_link_libraries(main PRIVATE stdc++exp) # For <print>
 endif()
 
+add_custom_command(
+   OUTPUT blargg_cpu_test5_official.log
+   COMMAND gzip -kd ${CMAKE_SOURCE_DIR}/test/blargg_cpu_test5_official.log.gz
+)
+add_custom_target(blargg_cpu_test5_official DEPENDS blargg_cpu_test5_official.log)
+
+add_dependencies(main blargg_cpu_test5_official)
+
 add_subdirectory(lib)
 
 enable_testing()
@@ -83,7 +91,7 @@ add_test(NAME blargg_cpu_test5_official_execute COMMAND main CPU_TEST blargg5off
 set_tests_properties(blargg_cpu_test5_official_execute PROPERTIES TIMEOUT 20)
 add_test(
     NAME blargg_cpu_test5_official_match
-    COMMAND diff    ${CMAKE_SOURCE_DIR}/test/blargg5Log.txt
-                    ${CMAKE_SOURCE_DIR}/test/blargg_cpu_test5_official.log
-                    --strip-trailing-cr
+    COMMAND python ${CMAKE_SOURCE_DIR}/test/logCompare.py
+        ${CMAKE_SOURCE_DIR}/test/blargg5Log.txt
+        ${CMAKE_SOURCE_DIR}/test/blargg_cpu_test5_official.log
 )
diff --git a/README.md b/README.md
index 881539e..54d1f3a 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ An incomplete NES emulator made using SDL2 and C++23.
 - ~~Basic source code layout~~
 - ~~ROM file input and processing~~
 - ~~Continuous integration / static analysis tool setup~~
-- ~~Official CPU opcode emulation~~
+- Official CPU opcode emulation
 - Full unofficial CPU opcode emulation
 - ~~Finish nestest support~~
 - Additional CPU tests
diff --git a/src/core/ppu.cpp b/src/core/ppu.cpp
index 75f8a2b..71c7a19 100644
--- a/src/core/ppu.cpp
+++ b/src/core/ppu.cpp
@@ -102,7 +102,8 @@ void PPU::cycle() {
             writeRegister(0x2, readRegister(0x2) | 0x80);
         }
         if (scanline == 261 && cyclesOnLine == 0) {
-            // Clear the vblank value on the second cycle of this line
+            // Clear the vblank bit on the second cycle of this line
+            // TODO: Also clear sprite overflow bit?
             writeRegister(0x2, readRegister(0x2) & ~0x80);
         }
     }
diff --git a/src/cpu/cpu_test.cpp b/src/cpu/cpu_test.cpp
index 75c137e..34a0e14 100644
--- a/src/cpu/cpu_test.cpp
+++ b/src/cpu/cpu_test.cpp
@@ -5,7 +5,7 @@
 struct TestCases {
     static const int NINTENDULATOR_OFFSET = 14; // This is how many cycles get added to the CPU in Nintendulator
     static const int NESTEST = 26555;
-    static const int BLARGG_TEST5_OFFICIAL = 3294894;
+    static const int BLARGG_TEST5_OFFICIAL = 3294894; // TODO: Update this to the full value
 };
 
 auto now() {
@@ -104,7 +104,7 @@ void runBlarggCpuTest5Official() {
         std::this_thread::yield();
     }
 
-    for (int i = 0; i < TestCases::BLARGG_TEST5_OFFICIAL - TestCases::NINTENDULATOR_OFFSET; i++) {
+    for (int i = 0; i < 3698351 - TestCases::NINTENDULATOR_OFFSET; i++) {
         nes->cpu->cycle();
     }
 
diff --git a/test/blargg_cpu_test5_official.log b/test/blargg_cpu_test5_official.log.gz
similarity index 61%
rename from test/blargg_cpu_test5_official.log
rename to test/blargg_cpu_test5_official.log.gz
index 6ece782..7d185f7 100644
Binary files a/test/blargg_cpu_test5_official.log and b/test/blargg_cpu_test5_official.log.gz differ
diff --git a/test/sources.txt b/test/sources.txt
new file mode 100644
index 0000000..e5ffc94
--- /dev/null
+++ b/test/sources.txt
@@ -0,0 +1,19 @@
+nestest.nes - 
+	From http://nickmass.com/images/nestest.nes
+	Found at https://www.nesdev.org/wiki/Emulator_tests
+nestest.log -
+	From https://www.qmtpro.com/~nes/misc/nestest.log
+	Found at https://www.nesdev.org/wiki/Emulator_tests
+
+blargg_cpu_test5_official.nes - From https://github.com/christopherpow/nes-test-roms/tree/master/blargg_nes_cpu_test5
+blargg_cpu_test5.nes - From https://github.com/christopherpow/nes-test-roms/tree/master/blargg_nes_cpu_test5
+Log files for blargg tests generated from Nintendulator via following process:
+- Load ROM
+- Open CPU debugger window
+- Press "Power", then "Reset", then "Start Log"
+- Run CPU until completion, then stop
+- Press "Stop Log" and retrieve log file
+When file is too large to store in one piece, broken into segments via `split <log file> -b 95M -d segment` and rejoined with `cat segment* > joined`.
+
+blargg_instr_test-v5 - From https://web.archive.org/web/20190319194832/http://blargg.8bitalley.com/nes-tests/instr_test-v5.zip
+