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5.4.5 Short direct addressing
[Function]
The memory to be manipulated in the fixed space is directly addressed with 8-bit data in an instruction word.
The fixed space where this addressing is applied to is the 256-byte space FE20H to FF1FH. An internal high-
speed RAM and a special function register (SFR) are mapped at FE20H to FEFFH and FF00H to FF1FH, respectively.
The SFR area (FF00H to FF1FH) where short direct addressing is applied is a part of all SFR areas. In this area,
ports which are frequently accessed in a program and a compare register of the timer/event counter and a capture
register of the timer/event counter are mapped and these SFRs can be manipulated with a small number of bytes
and clocks.
When 8-bit immediate data is at 20H to FFH, bit 8 of an effective address is set to 0. When it is at 00H to 1FH,
bit 8 is set to 1. Refer to [Illustration] on next page.
[Operand format]
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CHAPTER 5 CPU ARCHITECTURE
Identifier
saddr
Label or FE20H to FF1FH immediate data
saddrp
Label or FE20H to FF1FH immediate data (even address only)
Description
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