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microcode.txt

@@ -138,3 +138,81 @@ BCC
 CLC SEC CLI SEI CLD SED CLV
 ===========================
 
+---
+
+
+
+
+MICROINSTRUCTIONS
+===========================================
+
+FetchOpcode
+    DoOpcodeWork();
+    IR = Mem::Read(PC++);
+    Decode();
+    ResetState();
+
+FakeFetchOperand
+    Address.Lo = Mem::Read(PC);
+
+FetchOperandLo
+    Address.Lo = B = Mem::Read(PC++);
+
+FetchOperandHi
+    Address.Hi = Mem::Read(PC++);
+
+FetchOperandHiAndIndex
+    Address.Hi = Mem::Read(PC++);
+    if (Address.Lo+X/Y > 255) pageCrossed = true;
+    Address.Lo += X/Y;
+
+ReadAddress
+    B = Mem::Read(Address);
+    if (pageCrossed) Address += 0x0100;
+
+ReadAddressAndSkip
+    B = Mem::Read(Address);
+    if (pageCrossed)
+        Address += 0x0100;
+    else
+        InsertFetchOpcode();
+
+IndexX
+    B = Mem::Read(Address);
+    Address.Lo += X;
+
+FetchAddressLo
+    T = Mem::Read(Address++);
+
+FetchAddressHi
+    Address.Hi = Mem::Read(Address);
+    Address.Lo = T;
+
+FetchAddressHiAndIndex
+    Address.Hi = Mem::Read(Address);
+    pageCrossed = (T+Y > 255);
+    Address.Lo = T+Y;
+
+WriteRegister
+    if ((IR&3)==1) Mem::Write(Address, rA);
+    else if ((IR&3)==2) Mem::Write(Address, rX);
+    else if ((IR&3)==0) Mem::Write(Address, rY);
+
+WriteAddress
+    Mem::Write(Address, B);
+    DoOpcodeWork();
+
+CheckIfTaken
+    FakeFetchOperand();
+    If (!condition)
+        InsertFetchOpcode();
+    else
+        T = PC.Hi;
+        PC = PC +(int8_t)B;
+
+CheckIfPageCrossed
+    FakeFetchOperand();
+    if (PC.Hi == T)
+        InsertFetchOpCode();
+    else
+        pageCrossed = true;