3900/3950HD/3950C-HD (250-3580) Memory Upgrades Faxback Doc. # 2702 25-3582 - 2 MB RAM Module, available from National Parts (NP# XB5143). 25-3585 - 6 MB RAM Module, available from National Parts (NP# XB5142). This is a service center installed option. Consult your Radio Shack Service Technician for further information. System memory requires the unit be disassembled. This is not a user or store upgrade. The unit must be sent to repair. The 3900 has 2 MB of RAM soldered to the Main Logic Board. Just install the 6 MB RAM Module to expand the Notebook to 8 MB. The 3950HD/C has 2 MB of RAM soldered to the Main Logic Board, and a 2 MB RAM Module installed. To upgrade to 8 MB of RAM, take out the 2 MB RAM Module and replace it with the 6 MB RAM Module. (smc-02/18/94)