(1) flip the Notebook/Laptop PC over - see Fig.1 below
(2) find the memory cover - it really easy to find in this photo.
Fig.1 Toshiba M35X bottom view - the memory cover is seen at center left and secured by a single screw.
(3) remove the (1) screw securing the memory cover.
Fig. 2 Toshiba M35X laptop shown with memory cover removed and HDD (Hard Disk Drive) removed, and with the HDD cover flipped up.
The RAM (SO-DIMM boards) are visible at center left.
The HDD cover is seen at the bottom of the photo.
(4) Using proper anti-static/static control techniques, clip alligator clip or your anti-static wrist strap to a frame ground of the laptop at an I/O connector or frame ground under the HDD cover.
(5) carefully remove (2) old 256 MB SO-DIMM DDR333 memory modules.
Store old memory boards in the anti-static plastic baggie in which the new memory boards were shipped.
(6) install (2) new 1GB SO-DIMM DDR333 boards, for total of 2GB of system RAM.
(7) reassemble system, and boot OS (operating system).
The laptop's ROM BIOS will auto-detect the new RAM and begin a standard POST (Power-On Self Test).
(8) If OS is MSWindows, it will also auto-detect the new memory, and allocate it to application software.
The technology of the Toshiba Satellite M35X-S349 memory module is called
DDR333, meaning DDR (Double Data Rate) SDRAM (Synchronous Dynamic RAM), at a memory bus speed of 333 MHz.
The Form Factor of the DDR memory card is SO-DIMM, which stands for Small Outline DIMM (Dual In-line Memory Module) (see photo).
Fig.3 Each 1GB SO-DIMM DDR333 memory module will look like this one.
The Toshiba Satellite M35X-S349 supports a maximum of two SO-DIMM memory modules.
Each memory module can hold (a) 256MB, (b) 512MB, or (c) 1GB,
in the SO-DIMM Form Factor compatible with the Toshiba M35X-S349 Notebook PC.