4-2Theory of Operation
4.2.2 Memory Subsystem
The memory subsystem comprises the following components:
• Main memory
• L2 Secondary Memory (cache)
• Flash ROM
The Extensa Series uses fast Extended Data Out (EDO) DRAM for main and video memory and
high-speed synchronous, pipelined burst SRAM for L2 cache memory. Main BIOS and Video BIOS
are stored in Flash ROM.
4.2.2.1 Main Memory
The 67x Series Notebooks come standard with 16 MB main memory, expandable to 80 MB.
Memory expansion accommodations are provided via standard soDIMM connectors on the bottom
of the Motherboard Assembly.
4.2.2.2 Flash ROM
All versions of the Extensa notebook family use a "Flash" ROM that contains both the main system
BIOS and the VGA BIOS.
The Flash ROM execution is 8 bits wide. However, better performance can be attained by enabling
the Shadow ROM in the CMOS setup routine. When the Shadow ROM is enabled, BIOS is copied
into 32-bit high speed memory system.
4.2.3 Video Subsystem
The video subsystem is implemented on the Motherboard Assemblies.
The notebook contains a built-in 12.1 inch LCD and features simultaneous LCD and external VGA
display.
The video subsystem includes a 2 MB DRAM memory, 32-bit DRAM bus, and separate display and
memory clocks. An additional frame buffer/accelerator DRAM increases the available memory band
width for CPU accesses. The video section also uses additional levels of write FIFOs, a read cache,
page mode DRAM.
4.2.4 Sound Subsystem
The Extensa Series Notebook is equipped with a sound chip set that is Sound BlasterTM and Sound
Blaster Pro compatible. Internal stereo speakers provide the Notebook with sound generation
capabilities. A set of 3.5 mm connectors allow for external microphone and line inputs and
headphone/speaker outputs.
The sound subsystem also includes a variety of sound utilities that combine to provide additional
multi-media functions: