DS89C420-QCL Datasheet, PDF (2/139 Pages) Maxim Integrated Products – Ultra-High-Speed Flash Microcontroller User’s Guide

Ultra-High-Speed Flash
Microcontroller User’s Guide
SECTION 4: PROGRAMMING MODEL
8
Memory Organization
8
Memory Map
8
Register Map
8
Bit Addressable Locations
10
Working Registers
10
Stack
10
Address Modes
10
Program Status Flags
12
Special-Function Register Locations
13
Special-Function Registers
16
SECTION 5: CPU TIMING
42
Oscillator
42
XTAL1
42
XTAL2
42
Oscillator Characteristics
42
Crystal Selection
42
System Clock Divide Control
43
Instruction Timing
44
Nonpage Mode External Timing
45
Page Mode 1 External Timing—Pages 1:0 = 10b (Four Cycles)
47
Page Mode 1 External Timing—Pages 1:0 = 01b (Two Cycles)
50
Page Mode 1 External Timing—Pages 1:0 = 00b (One Cycle)
51
Page Mode 2 External Timing—Pages 1:0 = 11b
53
Comparison to the 8051
53
SECTION 6: MEMORY ACCESS
58
Internal Flash Memory
58
ROMSize Feature
58
Flash Security Block/Lock Bits
59
Option Control Register Byte
59
Internal SRAM Memory
60
Program Memory Interface—Nonpage Mode
61
Program Memory Interface—Page Modes
62
Data Memory Interface
65
Nonpage Mode Data Memory Timing
70
Page Mode 1 Data Memory Timing—Pages 1:0 = 10b (Four Cycles)
71
Page Mode 1 Data Memory Timing—Pages 1:0 = 01b (Two Cycles)
72
Page Mode 1 Data Memory Timing—Pages 1:0 = 00b (One Cycle)
74
Page Mode 2 Data Memory Timing—Pages 1:0 = 11b (Four Cycles)
76
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