Jump to Subroutine Long (JSRL)
Jump to Boot ROM Subroutine (JSRB)
Return from Subroutine (RET)
Return from Subroutine and Skip (RETSK)
Return from Interrupt (RETI)
22.0 Instruction Set (Continued)
Jump Indirect. In this 1-byte instruction, the lower byte of
the jump address is obtained from a table stored in program
memory, with the Accumulator serving as the low order byte
of a pointer into program memory. For purposes of access-
ing program memory, the contents of the Accumulator are
written to PCL (temporarily). The data pointed to by the
Program Counter (PCH/PCL) is loaded into PCL, while PCH
remains unchanged.
Software Trap Interrupt (INTR)
Vector Interrupt Select (VIS)
22.4.3 Load and Exchange Instructions
Example: Jump Indirect
JID
The load and exchange instructions write byte values in
registers or memory. The addressing mode determines the
source of the data.
Reg/
Memory
PCU
Contents
Before
01 Hex
C4 Hex
26 Hex
Contents
After
Load (LD)
Load Accumulator Indirect (LAID)
Exchange (X)
01 Hex
32 Hex
26 Hex
PCL
Accumulator
Memory
Location
0126 Hex
22.4.4 Logical Instructions
The logical instructions perform the operations AND, OR,
and XOR (Exclusive OR). Other logical operations can be
performed by combining these basic operations. For ex-
ample, complementing is accomplished by exclusive-ORing
the Accumulator with FF Hex.
32 Hex
32 Hex
The VIS instruction is a special case of the Indirect Transfer
of Control addressing mode, where the double-byte vector
associated with the interrupt is transferred from adjacent
addresses in program memory into the Program Counter in
order to jump to the associated interrupt service routine.
Logical AND (AND)
Logical OR (OR)
Exclusive OR (XOR)
22.4.5 Accumulator Bit Manipulation Instructions
22.4 INSTRUCTION TYPES
The Accumulator bit manipulation instructions allow the user
to shift the Accumulator bits and to swap its two nibbles.
The instruction set contains a wide variety of instructions.
The available instructions are listed below, organized into
related groups.
Rotate Right Through Carry (RRC)
Rotate Left Through Carry (RLC)
Swap Nibbles of Accumulator (SWAP)
Some instructions test a condition and skip the next instruc-
tion if the condition is not true. Skipped instructions are
executed as no-operation (NOP) instructions.
22.4.6 Stack Control Instructions
Push Data onto Stack (PUSH)
Pop Data off of Stack (POP)
22.4.1 Arithmetic Instructions
The arithmetic instructions perform binary arithmetic such as
addition and subtraction, with or without the Carry bit.
22.4.7 Memory Bit Manipulation Instructions
Add (ADD)
The memory bit manipulation instructions allow the user to
set and reset individual bits in memory.
Add with Carry (ADC)
Subtract with Carry (SUBC)
Increment (INC)
Set Bit (SBIT)
Reset Bit (RBIT)
Decrement (DEC)
Decimal Correct (DCOR)
Clear Accumulator (CLR)
Set Carry (SC)
Reset Pending Bit (RPND)
22.4.8 Conditional Instructions
The conditional instruction test a condition. If the condition is
true, the next instruction is executed in the normal manner; if
the condition is false, the next instruction is skipped.
Reset Carry (RC)
22.4.2 Transfer-of-Control Instructions
If Equal (IFEQ)
The transfer-of-control instructions change the usual se-
quential program flow by altering the contents of the Pro-
gram Counter. The Jump to Subroutine instructions save the
Program Counter contents on the stack before jumping; the
Return instructions pop the top of the stack back into the
Program Counter.
If Not Equal (IFNE)
If Greater Than (IFGT)
If Carry (IFC)
If Not Carry (IFNC)
If Bit (IFBIT)
Jump Relative (JP)
If B Pointer Not Equal (IFBNE)
And Skip if Zero (ANDSZ)
Decrement Register and Skip if Zero (DRSZ)
Jump Absolute (JMP)
Jump Absolute Long (JMPL)
Jump Indirect (JID)
Jump to Subroutine (JSR)
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