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Central Processing Unit (CPU)
Instruction Set Overview
MC9S12T64Revision 1.1.1
MOTOROLA
Central Processing Unit (CPU)
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55
Access Detail
Notation
A single-letter code in the
Access Detail
column of
Figure 4
represents
a single CPU access cycle. An upper-case letter indicates a 16-bit
access.
Table 9 Machine Code Notation
dd
8-bit direct address from $0000 to $00FF; high byte is $00
ee
High byte of a 16-bit constant offset for indexed addressing
eb
Exchange/transfer postbyte
Low eight bits of a 9-bit signed constant offset in indexed addressing, or low byte of a 16-bit
constant offset in indexed addressing
hh
High byte of a 16-bit extended address
ii
8-bit immediate data value
jj
High byte of a 16-bit immediate data value
kk
Low byte of a 16-bit immediate data value
lb
Loop primitive (DBNE) postbyte
ll
Low byte of a 16-bit extended address
8-bit immediate mask value for bit manipulation instructions; bits that are set indicate bits to be
affected
pg
Program page or bank number used in CALL instruction
qq
High byte of a 16-bit relative offset for long branches
tn
Trap number from $30 to $39 or from $40 to $FF
Signed relative offset $80 (–128) to $7F (
+
127) relative to the byte following the relative offset byte,
or low byte of a 16-bit relative offset for long branches
xb
Indexed addressing postbyte
ff
mm
rr
Table 10 Access Detail Notation
f
Free cycle. During an
f
cycle, the CPU does not use the bus. An
f
cycle is always one cycle of the
system bus clock. An
f
cycle can be used by a queue controller or the background debug system to
perform a single-cycle access without disturbing the CPU.
g
Read PPAGE register. A
g
cycle is used only in CALL instructions and is not visible on the external
bus. Since PPAGE is an internal 8-bit register, a
g
cycle is never stretched.
I
Read indirect pointer. Indexed-indirect instructions use the 16-bit indirect pointer from memory to
address the instruction operand. An
I
cycle is a 16-bit read that can be aligned or misaligned. An
I
cycle is extended to two bus cycles if the MCU is operating with an 8-bit external data bus and the
corresponding data is stored in external memory. There can be additional stretching when the
address space is assigned to a chip-select circuit programmed for slow memory. An
I
cycle is also
stretched if it corresponds to a misaligned access to a memory that is not designed for single-cycle
misaligned access.
i
Read indirect PPAGE value. An
i
cycle is used only in indexed-indirect CALL instructions. The 8-bit
PPAGE value for the CALL destination is fetched from an indirect memory location. An
i
cycle is
stretched only when controlled by a chip-select circuit that is programmed for slow memory.
F
Freescale Semiconductor, Inc.
n
.