Intel 8253 - Immediate Addressing; Immediate Data

XA User Guide 6-6 4/17/98
6.2.5 SFR Addressing
This is identical to the direct addressing mode described before, except it addresses the 1K SFR
space. Although encoded into the same instruction field as the direct addressing described above,
this is actually a separate space. Instructions using this addressing mode contain an 10-bit SFR
address. The 1K SFR space is always directly addressed (400:7FFh) and is mapped directly
above the 1K direct-addressed RAM space.
Example: MOV R0H, 406h
4
Before: R0H contains 05h
406h contains A5h
After: R0H contains A5h
406h contains A5h
6.2.6 Immediate Addressing
In immediate addressing, the actual operand is given explicitly in the instruction.The immediate
operand is either an 4/5, 8 or 16-bit integer which constitutes the source operand. 4-bit short
immediate operands used with instructions ADDS and MOVS are sign extended.
Example: ADD R0L,#0B9h Before: R0 contains 13h
After: R0L contains CCh
Figure 6.5
4. The syntax always refers to the SFR address starting from the base address of 400H.
IMMEDIATE DATA
ALU
DESTINATION
B9h
R0L
REGISTER - IMMEDIATE
CCh (result)
ADD R0L, #B9h
13h