A-99
INSTRUCTION SET REFERENCE
Example:
The MCS 251 controller is operating in nonpage mode. An external 256-byte RAM using
multiplexed address/data lines (e.g., an Intel 8155 RAM/I/O/Timer) is connected to port 0.
Port 3 provides control lines for the external RAM. ports 1 and 2 are used for normal I/O. R0
and R1 contain 12H and 34H. Location 34H of the external RAM contains 56H. After
executing the instruction sequence
MOVX A,@R1
MOVX @R0,A
the accumulator and external RAM location 12H contain 56H.
Variations
MOVX A,@DPTR
Binary Mode
Source Mode
Bytes:
1
1
States:
5
5
Hex Code in:
Binary Mode = [Encoding]
Source Mode = [Encoding]
Operation:
MOVX
(A)
←
((DPTR))
MOVX A,@Ri
Binary Mode
Source Mode
Bytes:
1
1
States:
3
3
Hex Code in:
Binary Mode = [Encoding]
Source Mode = [A5][Encoding]
Operation:
MOVX
(A)
←
((Ri))
MOVX @DPTR,A
Binary Mode
Source Mode
Bytes:
1
1
States:
5
5
Hex Code in:
Binary Mode = [Encoding]
Source Mode = [Encoding]
Operation:
MOVX
((DPTR))
←
(A)
[Encoding]
1 1 1 0
0 0 0 0
[Encoding]
1 1 1 0
0 0 1 i
[Encoding]
1 1 1 1
0 0 0 0
Summary of Contents for 8XC251SA
Page 2: ......
Page 3: ...May 1996 8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual...
Page 18: ......
Page 19: ...1 Guide to This Manual...
Page 20: ......
Page 30: ......
Page 31: ...2 Architectural Overview...
Page 32: ......
Page 41: ...3 Address Spaces...
Page 42: ......
Page 63: ...4 Device Configuration...
Page 64: ......
Page 81: ...5 Programming...
Page 82: ......
Page 102: ......
Page 103: ...6 Interrupt System...
Page 104: ......
Page 120: ......
Page 121: ...7 Input Output Ports...
Page 122: ......
Page 132: ......
Page 133: ...8 Timer Counters and Watchdog Timer...
Page 134: ......
Page 153: ...9 Programmable Counter Array...
Page 154: ......
Page 170: ......
Page 171: ...10 Serial I O Port...
Page 172: ......
Page 187: ...11 Minimum Hardware Setup...
Page 188: ......
Page 197: ...12 Special Operating Modes...
Page 198: ......
Page 206: ......
Page 207: ...13 External Memory Interface...
Page 208: ......
Page 239: ...14 Programming and Verifying Nonvolatile Memory...
Page 240: ......
Page 250: ......
Page 251: ...A Instruction Set Reference...
Page 252: ......
Page 390: ......
Page 391: ...B Signal Descriptions...
Page 392: ......
Page 400: ......
Page 401: ...C Registers...
Page 402: ......
Page 436: ......
Page 437: ...Glossary...
Page 438: ......
Page 446: ......
Page 447: ...Index...
Page 448: ......
Page 458: ......