cop87l88rg National Semiconductor Corporation, cop87l88rg Datasheet - Page 29

• Manufacturer Part Number: cop87l88rg
• Description: 8-bit One-time Programmable Microcontroller With Kbytes Program Memory
• Manufacturer: National Semiconductor Corporation

Addressing Modes
There are ten addressing modes six for operand address-
ing and four for transfer of control
OPERAND ADDRESSING MODES
Register Indirect
This is the ‘‘normal’’ addressing mode The operand is the
data memory addressed by the B pointer or X pointer
Register Indirect (with auto post increment or
decrement of pointer)
This addressing mode is used with the LD and X instruc-
tions The operand is the data memory addressed by the B
pointer or X pointer This is a register indirect mode that
automatically post increments or decrements the B or X reg-
ister after executing the instruction
Direct
The instruction contains an 8-bit address field that directly
points to the data memory for the operand
Immediate
The instruction contains an 8-bit immediate field as the op-
erand
Short Immediate
This addressing mode is used with the Load B Immediate
instruction The instruction contains a 4-bit immediate field
as the operand
Indirect
This addressing mode is used with the LAID instruction The
contents of the accumulator are used as a partial address
(lower 8 bits of PC) for accessing a data operand from the
program memory
TRANSFER OF CONTROL ADDRESSING MODES
Relative
This mode is used for the JP instruction with the instruction
field being added to the program counter to get the new
program location JP has a range from
a 1-byte relative jump (JP
instruction) There are no ‘‘pages’’ when using JP since all
15 bits of PC are used
Absolute
This mode is used with the JMP and JSR instructions with
the instruction field of 12 bits replacing the lower 12 bits of
the program counter (PC) This allows jumping to any loca-
tion in the current 4k program memory segment
Absolute Long
This mode is used with the JMPL and JSRL instructions
with the instruction field of 15 bits replacing the entire 15
bits of the program counter (PC) This allows jumping to any
location up to 32k in the program memory space
a
1 is implemented by a NOP
b
31 to
a
32 to allow
29
Indirect
This mode is used with the JID instruction The contents of
the accumulator are used as a partial address (lower 8 bits
of PC) for accessing a location in the program memory The
contents of this program memory location serve as a partial
address (lower 8 bits of PC) for the jump to the next instruc-
tion
Note The VIS is a special case of the Indirect Transfer of Control address-
Instruction Set
Register and Symbol Definition
MD
Mem
Meml
Imm
Reg
Bit
A
B
X
SP
PC
PU
PL
C
HC
GIE
VU
VL
B
X
ing mode where the double byte vector associated with the interrupt
is transferred from adjacent addresses in the program memory into
the program counter (PC) in order to jump to the associated interrupt
service routine
8-Bit Accumulator Register
8-Bit Address Register
8-Bit Address Register
8-Bit Stack Pointer Register
15-Bit Program Counter Register
Upper 7 Bits of PC
Lower 8 Bits of PC
1 Bit of PSW Register for Carry
1 Bit of PSW Register for Half Carry
1 Bit of PSW Register for Global
Interrupt Enable
Interrupt Vector Upper Byte
Interrupt Vector Lower Byte
Memory Indirectly Addressed by B
Register
Memory Indirectly Addressed by X
Register
Direct Addressed Memory
Direct Addressed Memory or B
Direct Addressed Memory or B or
Immediate Data
8-Bit Immediate Data
Register Memory Addresses F0 to FF
(Includes B X and SP)
Bit Number (0 to 7)
Loaded with
Exchanged with
Registers
Symbols
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