diff --git a/decoder.cpp b/decoder.cpp
index 48c0aa6..ad322b2 100644
--- a/decoder.cpp
+++ b/decoder.cpp
@@ -28,7 +28,28 @@ int InstructionDecoder::decode_and_execute(uint8_t opcode)
     printf("In decode and execute: op: %x, pc: %x\n", opcode, cpu->pc);
 
     // todo: single byte instructions
+    if((opcode & 0x8) == 0x8)           // 0b1000
+    {
+
+    }
+    else if((opcode & 0xA) == 0xA)      // 0b1010
+    {
+
+    }
+
     // todo: BRK, JSR abs, RTI, RTS
+    switch(opcode)
+    {
+        case 0x0:           // BRK
+            break;
+        case 0x20:          // JSR abs
+            break;
+        case 0x40:          // RTI
+            break;
+        case 0x60:          // RTS
+            break;
+    }
+
 
     // The conditional branch instructions all have the form xxy10000
     // they use relative addressing
@@ -43,6 +64,7 @@ int InstructionDecoder::decode_and_execute(uint8_t opcode)
         }
     }
     // form aaabbbcc instruction
+    // todo: perhaps make this more specific than just else
     else
     {
         decode_aaabbbcc(opcode);
diff --git a/runrom.cpp b/runrom.cpp
index 58ef716..fafe08c 100644
--- a/runrom.cpp
+++ b/runrom.cpp
@@ -25,10 +25,8 @@ int main(int argc, char**argv)
     // create and init state machine
     Famicom * nes = new Famicom(buffer);
 
-    /* engine to iterate through buffer,
-       call opcode->f() for each opcode passed in */
 
-    /* so this is iterating over the prgrom, which I believe contains the instructions... */
+    /* so this is iterating over the prgrom */
     while (nes->getpc() < PRGROMSTART+nes->cart->prgromsize)
     {
         //printf("%x : %x\n", nes->getpc(), fsize);
diff --git a/tests/systemtests.h b/tests/systemtests.h
index d2d1079..84816d1 100644
--- a/tests/systemtests.h
+++ b/tests/systemtests.h
@@ -123,7 +123,12 @@ class TestDecoder : public CppUnit::TestFixture
         void setUp();
         void test_branching();
         void test_aaabbbcc();
-        void test_singlebyte();
+        void test_singlebyte0x8();
+        void test_singlebyte0xa();
+        void test_brk();
+        void test_rti();
+        void test_jsrabs();
+        void test_rts();
 };
 
 CPPUNIT_TEST_SUITE_REGISTRATION( TestDecoder );