diff --git a/pass1.cpp b/pass1.cpp
index 633eb91..0df7211 100644
--- a/pass1.cpp
+++ b/pass1.cpp
@@ -8,7 +8,7 @@ using namespace std;
 bool error_flag=false;
 int program_length;
 
-void handle_LTORG(string& litPrefix, int& lineNumberDelta,int lineNumber,int& LOCCTR, int& lastDeltaLOCCTR){
+void handle_LTORG(string& litPrefix, int& lineNumberDelta,int lineNumber,int& LOCCTR, int& lastDeltaLOCCTR, int currentBlockNumber){
   string litAddress,litValue;
   litPrefix = "";
   for(auto const& it: LITTAB){
@@ -21,7 +21,7 @@ void handle_LTORG(string& litPrefix, int& lineNumberDelta,int lineNumber,int& LO
       lineNumber += 5;
       lineNumberDelta += 5;
       LITTAB[it.first].address = intToStringHex(LOCCTR);
-      litPrefix += "\n" + to_string(lineNumber) + "\t" + intToStringHex(LOCCTR) + "\t" + "*" + "\t" + "="+litValue + "\t" + " " + "\t" + " ";
+      litPrefix += "\n" + to_string(lineNumber) + "\t" + intToStringHex(LOCCTR) + "\t" + to_string(currentBlockNumber) + "\t" + "*" + "\t" + "="+litValue + "\t" + " " + "\t" + " ";
 
       if(litValue[0]=='X'){
         LOCCTR += (litValue.length() -3)/2;
@@ -48,6 +48,10 @@ void pass1(){
   string writeData,writeDataSuffix="",writeDataPrefix="";
   int index=0;
 
+  string currentBlockName = "DEFAULT";
+  int currentBlockNumber = 0;
+  int totalBlocks = 1;
+
   bool statusCode;
   string label,opcode,operand,comment;
   string tempOperand;
@@ -76,7 +80,7 @@ void pass1(){
     // cout<<startAddress<<endl;
     // exit(0);
     LOCCTR = startAddress;
-    writeData = to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment;
+    writeData = to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + to_string(currentBlockNumber) + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment;
     writeToFile(intermediateFile,writeData); // Write file to intermediate file
 
     getline(sourceFile,fileLine); //Read next line
@@ -186,7 +190,7 @@ void pass1(){
       }
       else if(opcode=="LTORG"){
         operand = " ";
-        handle_LTORG(writeDataSuffix,lineNumberDelta,lineNumber,LOCCTR,lastDeltaLOCCTR);
+        handle_LTORG(writeDataSuffix,lineNumberDelta,lineNumber,LOCCTR,lastDeltaLOCCTR,currentBlockNumber);
       }
       else if(opcode=="ORG"){
         readFirstNonWhiteSpace(fileLine,index,statusCode,operand);
@@ -199,6 +203,19 @@ void pass1(){
           LOCCTR = stringHexToInt(SYMTAB[operand].address);
         }
       }
+      else if(opcode=="USE"){
+        readFirstNonWhiteSpace(fileLine,index,statusCode,operand);
+        BLOCKS[currentBlockName].LOCCTR = intToStringHex(LOCCTR);
+
+        if(BLOCKS[operand].exists=='n'){
+          BLOCKS[operand].exists = 'y';
+          BLOCKS[operand].name = operand;
+          BLOCKS[operand].number = totalBlocks++;
+          BLOCKS[operand].LOCCTR = intToStringHex(LOCCTR);
+        }
+        currentBlockNumber = BLOCKS[operand].number;
+        LOCCTR = stringHexToInt(BLOCKS[operand].LOCCTR);
+      }
       else if(opcode=="EQU"){
         readFirstNonWhiteSpace(fileLine,index,statusCode,operand);
         tempOperand = "";
@@ -257,10 +274,10 @@ void pass1(){
             }
             else if((singleOperator=="-" || singleOperator=="+" || singleOperator=="?")&&lastOperand==1){
               if(singleOperator=="-"){
-                pairCount += -1;
+                pairCount--;
               }
               else{
-                pairCount += 1;
+                pairCount++;
               }
             }
 
@@ -294,12 +311,14 @@ void pass1(){
             if(pairCount==1){
               /*relative*/
               relative = 1;
-              /*tempOperand = eval(valueString)*/
+              EvaluateString tempOBJ(valueString);
+              tempOperand = intToStringHex(tempOBJ.getResult(),6);
             }
             else if(pairCount==0){
               /*absolute*/
               relative = 0;
-              /*tempOperand = eval(valueString)*/
+              EvaluateString tempOBJ(valueString);
+              tempOperand = intToStringHex(tempOBJ.getResult(),6);
             }
             else{
               writeData = "Line: "+to_string(lineNumber)+" : Illegal expression";
@@ -326,7 +345,12 @@ void pass1(){
         error_flag = true;
       }
       readFirstNonWhiteSpace(fileLine,index,statusCode,comment,true);
-      writeData = writeDataPrefix + to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment + writeDataSuffix;
+      if(opcode=="EQU" && SYMTAB[label].relative == 0){
+        writeData = writeDataPrefix + to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + " " + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment + writeDataSuffix;
+      }
+      else{
+        writeData = writeDataPrefix + to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + to_string(currentBlockNumber) + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment + writeDataSuffix;
+      }
       writeDataPrefix = "";
       writeDataSuffix = "";
     }
@@ -346,9 +370,9 @@ void pass1(){
   readFirstNonWhiteSpace(fileLine,index,statusCode,operand);
   readFirstNonWhiteSpace(fileLine,index,statusCode,comment,true);
 
-  handle_LTORG(writeDataSuffix,lineNumberDelta,lineNumber,LOCCTR,lastDeltaLOCCTR);
+  handle_LTORG(writeDataSuffix,lineNumberDelta,lineNumber,LOCCTR,lastDeltaLOCCTR,currentBlockNumber);
 
-  writeData = to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment + writeDataSuffix;
+  writeData = to_string(lineNumber) + "\t" + intToStringHex(LOCCTR-lastDeltaLOCCTR) + "\t" + " " + "\t" + label + "\t" + opcode + "\t" + operand + "\t" + comment + writeDataSuffix;
   writeToFile(intermediateFile,writeData);
 
   program_length = LOCCTR - startAddress;
diff --git a/tables.cpp b/tables.cpp
index bdfa6ca..575b0c0 100644
--- a/tables.cpp
+++ b/tables.cpp
@@ -37,6 +37,20 @@ struct struct_label{
        relative = 0;
      }
 };
+struct struct_blocks{
+     string startAddress;
+     string name;
+     string LOCCTR;
+     int number;
+     char exists;
+     struct_blocks(){
+       name="undefined";
+       startAddress="?";
+       exists='n';
+       number = -1;
+       LOCCTR = "0";
+     }
+};
 struct struct_register{
      char num;
      char exists;
@@ -50,11 +64,13 @@ typedef map<string,struct_label> SYMBOL_TABLE_TYPE;
 typedef map<string,struct_opcode> OPCODE_TABLE_TYPE;
 typedef map<string,struct_register> REG_TABLE_TYPE;
 typedef map<string,struct_literal> LIT_TABLE_TYPE;
+typedef map<string,struct_blocks> BLOCK_TABLE_TYPE;
 
 SYMBOL_TABLE_TYPE SYMTAB;
 OPCODE_TABLE_TYPE OPTAB;
 REG_TABLE_TYPE REGTAB;
 LIT_TABLE_TYPE LITTAB;
+BLOCK_TABLE_TYPE BLOCKS;
 
 void load_REGTAB(){
   REGTAB["A"].num='0';
@@ -322,7 +338,15 @@ void load_OPTAB(){
   OPTAB["WD"].exists='y';
 }
 
+void load_BLOCKS(){
+  BLOCKS["DEFAULT"].exists = 'y';
+  BLOCKS["DEFAULT"].name = "DEFAULT";
+  BLOCKS["DEFAULT"].startAddress = "?";
+  BLOCKS["DEFAULT"].number=0;
+  BLOCKS["DEFAULT"].LOCCTR = "0";
+}
 void load_tables(){
+  load_BLOCKS();
   load_OPTAB();
   load_REGTAB();
 }
diff --git a/utility.cpp b/utility.cpp
index 7c27c81..4cff373 100644
--- a/utility.cpp
+++ b/utility.cpp
@@ -160,3 +160,80 @@ char getFlagFormat(string data){
   }
   return ' ';
 }
+
+class EvaluateString{
+public:
+  int getResult();
+  EvaluateString(string data);
+private:
+  string storedData;
+  int index;
+  char peek();
+  char get();
+  int term();
+  int factor();
+  int number();
+};
+
+EvaluateString::EvaluateString(string data){
+  storedData = data;
+  index=0;
+}
+
+int EvaluateString::getResult(){
+  int result = term();
+  while(peek()=='+' || peek() == '-'){
+    if(get() == '+'){
+      result += term();
+    }else{
+      result -= term();
+    }
+  }
+  return result;
+}
+
+int EvaluateString::term(){
+  int result = factor();
+  while(peek() == '*' || peek() == '/'){
+    if(get()=='*'){
+      result *= factor();
+    }
+    else{
+      result /= factor();
+    }
+  }
+  return result;
+}
+
+int EvaluateString::factor(){
+  if(peek() >= '0' && peek() <= '9'){
+    return number();
+  }
+  else if(peek() == '('){
+    get();
+    int result = getResult();
+    get();
+    return result;
+  }
+  else if(peek()=='-'){
+    get();
+    return -factor();
+  }
+  return 0;
+}
+
+int EvaluateString::number(){
+  int result = get() - '0';
+  while(peek() >= '0' && peek() <= '9'){
+    result = 10*result + get()-'0';
+  }
+  return result;
+}
+
+char EvaluateString::get(){
+  return storedData[index++];
+}
+
+char EvaluateString::peek(){
+  return storedData[index];
+}