4-4 Theory of Operation
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:
4.2.5 Keyboard Subsystem
The keyboard subsystem, implemented on the Keyboard Assembly and the Motherboard
Assemblies Board, consists of the following major sections:
Keyboard Assembly
Keyboard Scanner
Status LED Interface
4.2.6 Hard Disk Drive Subsystem
The Hard Disk Drive Subsystem, implemented on the Motherboard Board and on the
associated hard disk drive module(s), provides disk storage for all system software and
user files.
The notebook is equipped with an 810 MB or larger hard disk drive. The hard disk
drive also features built-in power conservation features configured from the standard
CMOS Setup Routine. An Automatic Power Down mode can be selected which powers
down the drive motor during periods of inactivity. An additional level of power
conservation may also be selected which powers down the motor plus all control circuits.
The hard disk drives are factory formatted as a single drive (Drive C:) and are preloaded
with installation versions of Windows 95 or Windows for Workgroups (in dual load
versions, the user selects operating system during software installation).

4.2.6.1 Hard Disk Drive Power Management

Both the internal hard disk drive and the hard disk drive installed in the media bay