GameBoy\Core::setCurrentMBC1ROMBank PHP Method

    public function setCurrentMBC1ROMBank()
    {
        //Read the cartridge ROM data from RAM memory:
        switch ($this->ROMBank1offs) {
            case 0x0:
            case 0x20:
            case 0x40:
            case 0x60:
                //Bank calls for 0x00, 0x20, 0x40, and 0x60 are really for 0x01, 0x21, 0x41, and 0x61.
                $this->currentROMBank = $this->ROMBank1offs * 0x4000;
                break;
            default:
                $this->currentROMBank = ($this->ROMBank1offs - 1) * 0x4000;
        }
        while ($this->currentROMBank + 0x4000 >= count($this->ROM)) {
            $this->currentROMBank -= count($this->ROM);
        }
    }