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Intel Embedded Intel486 User Manual
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Table of Contents
Table of Contents
3
Chapter 1 Guide to this Manual
19
Manual Contents
19
Special Terminology
22
Electronic Support Systems
23
Faxback Service
23
World Wide Web
23
Technical Support
23
Product Literature
24
Related Documents
24
Chapter 2 Introduction
27
Processor Features
30
Intel486™ PROCESSOR PRODUCT FAMILY
32
Memory Management
33
Operating Modes and Compatibility
33
Floating-Point Unit
34
On-Chip Cache
34
Upgrade Power down Mode
35
System Architecture
35
Single Processor System
36
Loosely Coupled Multi-Processor System
37
External Cache
38
System Components
35
Systems Applications
39
Embedded Controllers
40
Embedded Personal Computers
40
3 Internal Architecture
43
Chapter 3 Internal Architecture
43
Instruction Pipelining
50
Bus Interface Unit
51
Data Transfers
52
Write Buffers
52
I/O Transfers
53
Locked Cycles
53
Cache Unit
54
Cache Structure
54
Cache Configuration
56
Cache Replacement
56
Cache Updating
56
Instruction Prefetch Unit
57
Control Unit
58
Instruction Decode Unit
58
Integer (Datapath) Unit
58
Floating-Point Unit
59
Inteldx2™ and Inteldx4™ Processor On-Chip Floating-Point Unit
59
Segmentation Unit
59
3.10 Paging Unit
60
Chapter 4 Bus Operation
63
Data Transfer Mechanism
65
Memory and I/O Spaces
65
Memory and I/O Space Organization
66
Dynamic Data Bus Sizing
67
Interfacing with 8-, 16-, and 32-Bit Memories
69
Dynamic Bus Sizing During Cache Line Fills
73
Operand Alignment
74
Bus Arbitration Logic
76
Bus Functional Description
79
No Wait States
80
Non-Cacheable Non-Burst Single Cycle
80
Inserting Wait States
81
Multiple and Burst Cycle Bus Transfers
81
Burst Cycles
82
Non-Cacheable, Non-Burst, Multiple Cycle Transfers
83
Terminating Multiple and Burst Cycle Transfers
83
Non-Cacheable Burst Cycles
84
Cacheable Cycles
85
Byte Enables During a Cache Line Fill
86
Non-Burst Cacheable Cycles
87
Burst Cacheable Cycles
88
Effect of Changing KEN# During a Cache Line Fill
89
Adding Wait States to Burst Cycles
90
Burst Mode Details
90
Burst and Cache Line Fill Order
91
Interrupted Burst Cycles
92
8- and 16-Bit Cycles
93
Locked Cycles
95
Pseudo-Locked Cycles
96
Floating-Point Read and Write Cycles
97
Invalidate Cycles
97
Rate of Invalidate Cycles
99
Running Invalidate Cycles Concurrently with Line Fills
99
Bus Hold
102
4.3.10 Interrupt Acknowledge
104
4.3.11 Special Bus Cycles
105
HALT Indication Cycle
105
Shutdown Indication Cycle
105
Stop Grant Indication Cycle
105
4.3.12 Bus Cycle Restart
107
4.3.13 Bus States
109
Floating-Point Error Handling for the Inteldx2™ and Inteldx4™ Processors
110
Floating-Point Exceptions
110
Inteldx2™ and Inteldx4™ Processors Floating-Point Error Handling in AT-Compatible Systems
111
Enhanced Bus Mode Operation (Write-Back Mode)
114
Burst Cycles
114
Summary of Bus Differences
114
Burst Cycle Signal Protocol
115
Non-Cacheable Burst Operation
115
Cache Consistency Cycles
116
Snoop Collision with a Current Cache Line Operation
118
Snoop under AHOLD
118
Snoop During Replacement Write-Back
123
Snoop under BOFF
125
Snoop under HOLD
128
Snoop under HOLD During Replacement Write-Back
130
Locked Cycles
131
Snoop/Lock Collision
132
Flush Operation
133
Pseudo Locked Cycles
134
Snoop under AHOLD During Pseudo-Locked Cycles
134
Snoop under Hold During Pseudo-Locked Cycles
135
Snoop under BOFF# Overlaying a Pseudo-Locked Cycle
136
Chapter 5 Memory Subsystem Design
139
Introduction
141
Processor and Cache Feature Overview
141
The Burst Cycle
141
The KEN# Input
142
Bus Characteristics
144
Improving Write Cycle Latency
145
Interleaving
145
Write Posting
145
Second-Level Cache
146
6 Cache Subsystem
149
Chapter 6 Cache Subsystem
149
Cache Memory
151
What Is a Cache
151
Why Add an External Cache
152
Introduction
151
Cache Trade-Offs
152
Cache Size and Performance
153
Associativity and Performance Issues
155
Block/Line Size
160
Replacement Policy
161
Updating Main Memory
161
Write-Through and Buffered Write-Through Systems
162
Cache Consistency
163
Write-Back System
163
Non-Cacheable Memory Locations
165
Cache and Dma Operations
166
Cache for Single Versus Multiple Processor Systems
166
Cache in Multiple Processor Systems
166
Cache in Single Processor Systems
166
AN Intel486™ PROCESSOR SYSTEM EXAMPLE
168
The Memory Hierarchy and Advantages of a Second-Level Cache
169
7 Peripheral Subsystem
171
Chapter 7 Peripheral/Processor Bus Interface
173
Mapping Techniques
173
Dynamic Bus Sizing
175
Address Decoding for I/O Devices
177
Address Bus Interface
178
8-Bit I/O Interface
179
16-Bit I/O Interface
182
32-Bit I/O Interface
186
Basic Peripheral Subsystem
189
Bus Control and Ready Logic
192
Bus Control Signal Description
193
Processor Interface
193
Wait State Generation Signals
194
Wait State Generator Logic
194
Address Decoder
195
Data Transceivers
198
Recovery and Bus Contention
198
Non-Cacheability of Memory-Mapped I/O Devices
199
Write Buffers and I/O Cycles
199
Write Buffers and Recovery Time
199
Intel486™ Processor On-Chip Cache Consistency
200
I/O Cycles
201
Read Cycle Timing
201
Write Cycle Timings
203
DIFFERENCE between the Intel486 DX PROCESSOR FAMILY and Intel386 PROCESSORS
205
INTERFACING to X86 PERIPHERALS
206
Universal Peripheral Interface
206
82C59A Interface
207
Single Interrupt Controller
207
Cascaded Interrupt Controllers
209
Handling more than 64 Interrupts
210
Intel486™ PROCESSOR LAN CONTROLLER INTERFACE
210
82596CA Coprocessor
210
Hardware Interface
213
Processor and Coprocessor Interaction
216
Media Access
218
Memory Structure
218
Bus Throttle Timers
219
Transmit and Receive Operation
219
Design Considerations
220
82596 Co-Processor Performance
221
82557 High Speed LAN Controller Interface
222
82557 Overview
222
Features and Enhancements
223
82557 Bus Operations
224
Initializing the 82557
224
PCI Bus Interface
224
Controlling the 82557
225
8 System Bus Design
227
Chapter 8
229
Introduction
229
System Bus Interface
229
Eisa Bus: System Design Example
230
Introduction to the EISA Architecture
230
An Example EISA Chip Set
231
Clock, Control and Status Interface
237
EBC Host Bus Interface
237
Host Bus Acquisition and Release
238
Host Local Memory and I/O Interface
238
Lock, Snoop, and Address Greater than 16 Mbytes
238
EBC and EISA Bus Interface Signals
239
EISA/ISA Bus Interface to the EBC
239
EBC and ISA Bus Interface Signals
240
EBC and ISP Interface
241
EBC and EBB Data and Address Buffer Controls
242
Functions of the ISP
244
ISP-To-EISA Interface
245
ISP-To-Host Interface
245
Pci Bus: System Design Example
247
Example PCI System Design
247
Introduction to PCI Architecture
247
Control and Status Interface
252
Host Bus Slave Device
252
Host CPU Interface
252
L1 Cache Support
252
PCI Bus Cycles Support
254
Exclusive Cycles
255
Host to PCI Cycles
255
Status and Control Interface
256
Status and Control Interface
257
System Controller/Isa Bridge Link Interface
257
Data Byte Swapping (ISA Master or DMA to ISA Device)
258
I/O Recovery Support
258
ISA Interface
258
SYSCLK Generation
258
Wait-State Generation
259
9 Performance
263
Performance Considerations
263
Introduction
265
Instruction Execution Performance
266
Internal Cache Performance Issues
268
On-Chip Write Buffers
271
External Memory Considerations
272
Second-Level Cache Performance Considerations
275
Dram Design Techniques
278
Extended Data Output RAM (EDO RAM)
278
Floating-Point Performance
280
10 Physical Design and
283
10.1 General System Guidelines
285
10.2 Power Dissipation and Distribution
285
10.3 High-Frequency Design Considerations
293
10.4 Latch-Up
314
10.5 Clock Considerations
314
10.6 Thermal Characteristics
317
10.7 Derating Curve and Its Effects
320
Building and Debugging the Intel486™ Processor-Based System
321
4
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Intel Embedded Intel486 Specifications
General
Brand
Intel
Model
Embedded Intel486
Category
Computer Hardware
Language
English
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