A-3
INSTRUCTION SET REFERENCE
Table A-2. Notation for Direct Addresses
Direct
Address.
Description
MCS
®
251
Arch.
MCS 51
Arch.
dir8
An 8-bit direct address. This can be a memory address
(00:0000H–00:00FFH) or an SFR address (S:00H - S:FFH).
✔
✔
dir16
A 16-bit memory address (00:0000H–00:FFFFH) used in direct
addressing.
✔
Table A-3. Notation for Immediate Addressing
Immediate
Data
Description
MCS
®
251
Arch.
MCS 51
Arch.
#data
An 8-bit constant that is immediately addressed in an instruction.
✔
✔
#data16
A 16-bit constant that is immediately addressed in an instruction.
✔
#0data16
#1data16
A 32-bit constant that is immediately addressed in an instruction. The
upper word is filled with zeros (#0data16) or ones (#1data16).
✔
#short
v v
A constant, equal to 1, 2, or 4, that is immediately addressed in an
instruction.
Binary representation of #short.
✔
Table A-4. Notation for Bit Addressing
Bit
Address
Description
MCS
®
251
Arch.
MCS 51
Arch.
bit
y y y
A directly addressed bit in memory locations 00:0020H–00:007FH or in
any defined SFR.
A binary representation of the bit number (0–7) within a byte.
✔
bit51
A directly addressed bit (bit number = 00H–FFH) in memory or an SFR.
Bits 00H–7FH are the 128 bits in byte locations 20H–2FH in the on-chip
RAM. Bits 80H–FFH are the 128 bits in the 16 SFR’s with addresses
that end in 0H or 8H: S:80H, S:88H, S:90H, . . . , S:F0H, S:F8H.
✔
Table A-5. Notation for Destinations in Control Instructions
Destination
Address
Description
MCS
®
251
Arch.
MCS 51
Arch.
rel
A signed (two's complement) 8-bit relative address. The destination is
-128 to +127 bytes relative to first byte of the next instruction.
✔
✔
addr11
An 11-bit destination address. The destination is in the same 2-Kbyte
block of memory as the first byte of the next instruction.
✔
✔
addr16
A 16-bit destination address. A destination can be anywhere within
the same 64-Kbyte region as the first byte of the next instruction.
✔
✔
addr24
A 24-bit destination address. A destination can be anywhere within
the 16-Mbyte address space.
✔
Содержание 8XC251SA
Страница 2: ......
Страница 3: ...May 1996 8XC251SA 8XC251SB 8XC251SP 8XC251SQ Embedded Microcontroller User s Manual...
Страница 18: ......
Страница 19: ...1 Guide to This Manual...
Страница 20: ......
Страница 30: ......
Страница 31: ...2 Architectural Overview...
Страница 32: ......
Страница 41: ...3 Address Spaces...
Страница 42: ......
Страница 63: ...4 Device Configuration...
Страница 64: ......
Страница 81: ...5 Programming...
Страница 82: ......
Страница 102: ......
Страница 103: ...6 Interrupt System...
Страница 104: ......
Страница 120: ......
Страница 121: ...7 Input Output Ports...
Страница 122: ......
Страница 132: ......
Страница 133: ...8 Timer Counters and Watchdog Timer...
Страница 134: ......
Страница 153: ...9 Programmable Counter Array...
Страница 154: ......
Страница 170: ......
Страница 171: ...10 Serial I O Port...
Страница 172: ......
Страница 187: ...11 Minimum Hardware Setup...
Страница 188: ......
Страница 197: ...12 Special Operating Modes...
Страница 198: ......
Страница 206: ......
Страница 207: ...13 External Memory Interface...
Страница 208: ......
Страница 239: ...14 Programming and Verifying Nonvolatile Memory...
Страница 240: ......
Страница 250: ......
Страница 251: ...A Instruction Set Reference...
Страница 252: ......
Страница 390: ......
Страница 391: ...B Signal Descriptions...
Страница 392: ......
Страница 400: ......
Страница 401: ...C Registers...
Страница 402: ......
Страница 436: ......
Страница 437: ...Glossary...
Страница 438: ......
Страница 446: ......
Страница 447: ...Index...
Страница 448: ......
Страница 458: ......