Placement Of 16-Bit Data In Memory - Fujitsu F2MC-8FX Hardware Manual

5.3

Placement of 16-bit Data in Memory

This section describes how 16-bit data is stored in memory.
Placement of 16-bit Data in Memory
State of 16-bit data stored in RAM
When you write 16-bit data to memory, the upper byte of the data is stored at a smaller address and the
lower byte is stored at the next address. When you read 16-bit data, it is handled in the same way.
Figure 5.3-1 shows how 16-bit data is placed in memory.
State of operand-specified 16-bit data
In the same way, even when the operands in an instruction specifies 16-bit data, the upper byte is stored at
the address closer to the op-code (instruction) and the lower byte is stored at the next address.
That is true whether the operands are either memory addresses or 16-bit immediate data.
Figure 5.3-2 shows how 16-bit data in an instruction is placed.
State of 16-bit data in the stack
When 16-bit register data is pushed onto the stack upon an interrupt, the upper byte is stored at a lower
address in the same way.
Figure 5.3-1 Placing 16-bit Data in Memory
Before
Memory
execution
Figure 5.3-2 Storing 16-bit Data in Instruction
[Example]
After
Memory
execution
Extended address
16-bit immediate data
Assemble
Extended address
16-bit immediate data
CHAPTER 5 CPU
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