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8XC251SA, SB, SP, SQ USER’S MANUAL
iv
3.3.2.3 Extended Stack Pointer, SPX ............................................................................3-15
3.4 SPECIAL FUNCTION REGISTERS (SFRS) ............................................................... 3-16
CHAPTER 4
DEVICE CONFIGURATION
4.1 CONFIGURATION OVERVIEW .................................................................................... 4-1
4.2 DEVICE CONFIGURATION .......................................................................................... 4-1
4.3 THE CONFIGURATION BITS........................................................................................ 4-4
4.4 CONFIGURATION BYTE LOCATION SELECTOR (UCON)......................................... 4-5
4.5 CONFIGURING THE EXTERNAL MEMORY INTERFACE........................................... 4-8
4.5.1 Page Mode and Nonpage Mode (PAGE#) ................................................................4-8
4.5.2 Configuration Bits RD1:0 ..........................................................................................4-9
4.5.2.1 RD1:0 = 00 (18 External Address Bits) ................................................................4-9
4.5.2.2 RD1:0 = 01 (17 External Address Bits) ................................................................4-9
4.5.2.3 RD1:0 = 10 (16 External Address Bits) ..............................................................4-12
4.5.2.4 RD1:0 = 11 (Compatible with MCS 51 Microcontrollers) ....................................4-12
4.5.3 Wait State Configuration Bits ..................................................................................4-12
4.5.3.1 Configuration Bits WSA1:0#, WSB1:# ...............................................................4-12
4.5.3.2 Configuration Bit WSB .......................................................................................4-12
4.5.3.3 Configuration Bit XALE# ....................................................................................4-13
4.6 OPCODE CONFIGURATIONS (SRC)......................................................................... 4-13
4.6.1 Selecting Binary Mode or Source Mode ..................................................................4-14
4.7 MAPPING ON-CHIP CODE MEMORY TO DATA MEMORY (EMAP#)...................... 4-16
4.8 INTERRUPT MODE (INTR)......................................................................................... 4-16
CHAPTER 5
PROGRAMMING
5.1 SOURCE MODE OR BINARY MODE OPCODES ........................................................ 5-1
5.2 PROGRAMMING FEATURES OF THE MCS® 251 ARCHITECTURE......................... 5-1
5.2.1 Data Types ................................................................................................................5-2
5.2.1.1 Order of Byte Storage for Words and Double Words ...........................................5-2
5.2.2 Register Notation ......................................................................................................5-2
5.2.3 Address Notation ......................................................................................................5-2
5.2.4 Addressing Modes ....................................................................................................5-4
5.3 DATA INSTRUCTIONS ................................................................................................. 5-4
5.3.1 Data Addressing Modes ............................................................................................5-4
5.3.1.1 Register Addressing .............................................................................................5-5
5.3.1.2 Immediate ............................................................................................................5-5
5.3.1.3 Direct ....................................................................................................................5-5
5.3.1.4 Indirect .................................................................................................................5-6
5.3.1.5 Displacement .......................................................................................................5-8
5.3.2 Arithmetic Instructions ...............................................................................................5-8
5.3.3 Logical Instructions ...................................................................................................5-9
5.3.4 Data Transfer Instructions .......................................................................................5-10