System Drivers - HP Vectra Technical Reference Manual

9.
SYSTEM DRIVERS
This section contains a description of the drivers which control the system functions. The drivers
discussed in previous sections deal with system peripherals such as the disc drives, keyboard,
video display adapter, etc. The drivers covered in this section control the system itself.
9.1 Overview
The system drivers are designed to provide program access to system operating parameters, and
to support ROM BIOS drivers. These drivers allow programs to determine the system equipment
configuration and amount of memory, provide "hooks" for future multi-tasking capability,
control vectors in the HP_VECTOLTABLE, allocate RAM in the EX-BIOS data area, control
system strings, manage CMOS memory, and perform system clock functions. An overview of the
capabilities of the drivers in each of these categories follows.
9.1.1 Memory Size And Equipment Determination
The ROM BIOS supports two industry standard drivers that report the current system equipment
configuration and memory size. These tasks are supported by the INT 11 Hand INT 12H drivers,
respectively.
The equipment determination driver (INT 11 H) returns a word that describes the current system
configuration. The definition of each bit or group of bits in the word is discussed later in this
section. The number of printer ports, serial ports, presence of an 80287 math coprocessor, initial
video display mode and number of flexible disc drives are reported by this driver. The default
system configuration is read from a CMOS memory location during power-on. If this information
does not match the current configuration, a power on error message is issued and the current
configuration is saved for the INT 11
H
driver.
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