Posts: 9
Threads: 3
Joined: Jan 1970
From the TDS manual, introduction, page 6, in speaking of RAM cards........"For users who have both an HP-48SX and an HP-48GX there is another advantage to the multi memory RAM cards.They can be swapped between the 48GX and 48SX with full use of the data in both systems. This applies ONLY to the multi memory RAM card and NOT the TDS-48GX survey program ROM cards. The ROM cards can only be used in the 48 for which they were programmed." Hope this helps you out.....for more try www.tdsway.com