Datasheet
Section 2 CPU 
R01UH0310EJ0500 Rev. 5.00    Page 75 of 1384 
Sep 25, 2012     
H8S/2426, H8S/2426R, H8S/2424 Group 
2.7.3  Register Indirect with Displacement—@(d:16, ERn) or @(d:32, ERn) 
A 16-bit or 32-bit displacement contained in the instruction is added to an address register (ERn) 
specified by the register field of the instruction code, and the sum gives the address of a memory 
operand. A 16-bit displacement is sign-extended when added. 
2.7.4  Register Indirect with Post-Increment or Pre-Decrement—@ERn+ or @-ERn 
Register indirect with post-increment—@ERn+: The register field of the instruction code 
specifies an address register (ERn) which contains the address of a memory operand. After the 
operand is accessed, 1, 2, or 4 is added to the address register contents and the sum is stored in the 
address register. The value added is 1 for byte access, 2 for word transfer instruction, or 4 for 
longword transfer instruction. For word or longword transfer instruction, the register value should 
be even. 
Register indirect with pre-decrement—@-ERn: The value 1, 2, or 4 is subtracted from an 
address register (ERn) specified by the register field in the instruction code, and the result 
becomes the address of a memory operand. The result is also stored in the address register. The 
value subtracted is 1 for byte access, 2 for word transfer instruction, or 4 for longword transfer 
instruction. For word or longword transfer instruction, the register value should be even. 
2.7.5  Absolute Address—@aa:8/@aa:16/@aa:24/@aa:32 
The instruction code contains the absolute address of a memory operand. The absolute address 
may be 8 bits long (@aa:8), 16 bits long (@aa:16), 24 bits long (@aa:24), or 32 bits long 
(@aa:32). Table 2.12 indicates the accessible absolute address ranges. 
To access data, the absolute address should be 8 bits (@aa:8), 16 bits (@aa:16), or 32 bits 
(@aa:32) long. For an 8-bit absolute address, the upper 24 bits are all assumed to be 1 (H'FFFF). 
For a 16-bit absolute address, the upper 16 bits are a sign extension. A 32-bit absolute address can 
access the entire address space. 
A 24-bit absolute address (@aa:24) indicates the address of a program instruction. The upper 8 
bits are all assumed to be 0 (H'00). 










