Upgrade Power Down Mode; System Components; System Architecture - Intel Embedded Intel486 Hardware Reference Manual

2.2.5

Upgrade Power Down Mode

Upgrade Power Down Mode on the Intel486 processor is initiated by the Intel OverDrive
cessor using the UP# (Upgrade Present) pin. Upon sensing the presence of the Intel OverDrive
Processor, the Intel486 processor three-states its outputs and enters the "Upgrade Power Down
Mode," lowering its power consumption. The UP# pin of the Intel486 processor is driven active
(low) by the UP# pin of the Intel OverDrive processor. (In the embedded Intel486 processor fam-
ily, the UP# pin has been renamed Reserved, with no changes in functionality.)
2.3

SYSTEM COMPONENTS

Intel offers several chips that are highly compatible with the Intel486 processor. These compo-
nents can be used to design high-performance embedded systems with a minimum of effort and
cost. For components not directly connectable to the Intel486 processor bus, industry-standard
interfaces can be used.
The Intel486 processor provides all integer and floating-point CPU functions plus many of the
peripheral functions required in a typical computer system. It executes the complete instruction
set of the Intel386 processor and Intel387 DX numerics coprocessor, with some extensions. The
processor eliminates the need for an external memory management unit, and the on-chip cache
minimizes the need for external cache and associated control logic.
The remaining chapters of this manual detail the Intel486 processor's architecture, hardware
functions, and interfacing. For more information on the architecture and software interface, see
the Embedded Intel486™ Processor Family Developer's Manual and the Intel Architecture Soft-
ware Developer's Manual, Volumes 1 and 2.
2.4

SYSTEM ARCHITECTURE

The Intel486 processor can be the foundation for single-processor or multi-processor embedded
systems. A single-processor system might be an embedded personal computer designed to use the
Intel486 processor. A system design of this type offers higher performance through the integra-
tion of floating-point processing, memory management, and caching. More complex embedded
systems may use multiple processors that provide, at chip-level, the equivalent of board-level
functions. Designs of this type are typically used in multi-user machines, scientific workstations,
and engineering workstations.
A typical Intel486 design is shown in
with external cache. Other examples of system design are illustrated in the figures that follow.
Figure 2-1. This example uses a single Intel486 processor
INTRODUCTION
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