If the memory card does not meet the following 2 requirements, you will hear continuous short beep from the GPS.
1. Memory Size <= 4GB
2. Memory must be formatted into FAT (FAT16) partition. FAT32 or other partitions do NOT work. The picture below shows the stpes to format a 4GB memory card by Windows 7.
BTW, don’t use Mac to format the memory card. It does not support FAT(FAT16).