HD6475328CG Datasheet, PDF (62/459 Pages) Hitachi Semiconductor – Manual Gives a Hardware Description

Table 3-5 Data Formats in Memory
Data Type
1-Bit (in byte
operand data)
1-Bit (in word
operand data)
Byte
Data Format
Address n
7
0
7 6 5 4 3 21 0
Even address 15 14 13 12 11 10 9 8
Odd address 7 6 5 4 3 2 1 0
Address n
MSB
LSB
Word
Even address MSB
Upper 8 bits
Odd address
Lower 8 bits
LSB
When the stack is accessed in exception processing (to save or restore the program counter, code
page register, or status register), word access is always performed, regardless of the actual data
size. Similarly, when the stack is accessed by an instruction using the pre-decrement or post-
increment register indirect addressing mode specifying R7 (@–R7 or @R7+), which is the stack
pointer, word access is performed regardless of the operand size specified in the instruction. An
address error will therefore occur if the stack pointer indicates an odd address. Programs should
be coded so that the stack pointer always indicates an even address.
Table 3-6 shows the data formats on the stack.
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