Chapter 1 Introduction to VL-Bus
2
American Megatrends VL-Bus Implementation
The VL-Bus
The VL-Bus is designed to standardize the hardware interface of peripherals connected to a
microprocessor-level local bus. The VL-Bus Specification is a standard set of interface, architecture,
timings, electrical, and physical specifications that permits all VL-Bus products to be totally
interchangeable.
VL-Bus is Based on 80486 Local Bus Design
The general architecture of the VL-Bus is designed to Intel® 80486 CPU local bus standards with
additional hardware functions that accommodate VL-Bus master devices and facilitate the system I/O bus
interface. The timing specifications allow VL-Bus devices to operate at the full 32-bit 80486 CPU
bandwidth.
Both VL-Bus slots on the Enterprise-III motherboard have bus mastering capability.
EISA and Local Bus Expansion
The American Megatrends Enterprise-III EISA Local Bus motherboard has six bus master EISA expansion
slots and two VL-Bus expansion slots. The VL-Bus slots consist of a standard EISA 32-bit slot connector
(with no EISA bus mastering capability but
full VL-Bus bus mastering
) and an inline VL-Bus connector.
