Printing and Vector Allocation in php cli

I'm doing a program in PHP that simulates the allocation of programs in a Memory. The problem is that it does not allocate the data in the vector. It prints the vector as if it were the same after its initialization

<?php
//  echo phpversion();
  define("MAX", 8);
  define("MAXMEM", 32);

  $tam;
  $valor;
  $memoria;
  $GLOBALS['$memoria'] = array();
  $inicio = 0;
  $Nalocacoes;

  Inicializar();
  Menu();

  return 0;



  //funcoes
  function AlocarProcesso(){

      echo "Digite o nome do processo:";
      $valor = fgets(STDIN);
      echo "Digite o tamanho do processo:";
      $tam = fgets(STDIN);

      $Nalocacoes=NumAlocacoes($tam);
      PreencherVetor($GLOBALS['$memoria'],$valor,$Nalocacoes);
      BubbleSort($GLOBALS['$memoria'], MAXMEM);

      return $GLOBALS['$memoria'];

      Menu();
  }


  function Inicializar(){
      for($i=0;$i<MAXMEM;$i++){
         $GLOBALS['$memoria'][$i]="VAZIO";
       }
  }
  function Listar($vetor, $n){
      for($i=0;$i<$n;$i++){
        echo "\n[".$i."] ".$vetor[$i];
      }
      Menu();
  }

  function NumAlocacoes($tam){
    if(($tam % MAX) == 0){
      $espacos = $tam/MAX;
    }
    else {
      $espacos = ((int) $tam/MAX)+1;
    }

    echo "Numero de Alocacoes: " . $espacos;
    return $espacos;


  }

  function PreencherVetor($vetor, $programa, $tam){

    for($i=0;$i<((MAXMEM/MAX)-1);$i++){
        if(strcmp($vetor[$i], "VAZIO") == 0){
          for($j=$i;$j<$tam;$j++){
            $vetor[$j] = $programa;


          }
        }


    }
    return $vetor;


  }
  function Menu(){
    $menu = 1;
    while ($menu) {
      echo "\n\n\n---------MENU----------\n";
      echo "1. Alocar Memoria -----\n";
      echo "2. Listar Memoria -----\n";
      echo "3. Desalocar Memoria --\n";
      echo "\n\n\n";

      $opt = fgets(STDIN);

      switch ($opt) {
        case 1:
          AlocarProcesso();
          break;
        case 2:
          //Listar($GLOBALS['$memoria'], MAXMEM);
          print_r($GLOBALS['$memoria']);
          Menu();
          break;
        case 3:
            DesalocarProcesso();
            break;
        default:
          $menu = 0;
          break;
      }
    }
  }
  function Desalocar($vetor, $valor){
      for($i = 0;$i<MAXMEM;$i++){
        if($vetor[$i] == $valor){
          $vetor[$i] = "VAZIO";
          $inicio --;
        }

      }
      BubbleSort($vetor, MAXMEM);
  }
  function DesalocarProcesso(){
    echo "Digite o processo: ";
    $valor = fgets(STDIN);
    Desalocar($GLOBALS['$memoria'],$valor);

  }

  function BubbleSort($data){
    $nowData = null;
    for ($i = 0; $i < count($data); $i++){
            for ($j = 0; $j < count($data); $j++){
                    if($data[$i] < $data[$j]){
                            $nowData = $data[$i];
                            $data[$i] = $data[$j];
                            $data[$j] = $nowData;
                    }
            }
    }
    return $data;
  }



?>