Go to the previous, next section.

H8/500 Dependent Features


as has no additional command-line options for the Hitachi H8/500 family.


Special Characters

`!' is the line comment character.

`;' can be used instead of a newline to separate statements.

Since `$' has no special meaning, you may use it in symbol names.

Register Names

You can use the predefined symbols `r0', `r1', `r2', `r3', `r4', `r5', `r6', and `r7' to refer to the H8/500 registers.

The H8/500 also has these control registers:

code pointer

data pointer

base pointer

stack top pointer

extra pointer

status register

condition code register

All registers are 16 bits long. To represent 32 bit numbers, use two adjacent registers; for distant memory addresses, use one of the segment pointers (cp for the program counter; dp for r0--r3; ep for r4 and r5; and tp for r6 and r7.

Addressing Modes

as understands the following addressing modes for the H8/500:

Register direct

Register indirect

@(d:8, Rn)
Register indirect with 8 bit signed displacement

@(d:16, Rn)
Register indirect with 16 bit signed displacement

Register indirect with pre-decrement

Register indirect with post-increment

8 bit absolute address

16 bit absolute address

8 bit immediate

16 bit immediate

Floating Point

The H8/500 family has no hardware floating point, but the .float directive generates IEEE floating-point numbers for compatibility with other development tools.

H8/500 Machine Directives

as has no machine-dependent directives for the H8/500. However, on this platform the `.int' and `.word' directives generate 16-bit numbers.


For detailed information on the H8/500 machine instruction set, see H8/500 Series Programming Manual (Hitachi M21T001).

as implements all the standard H8/500 opcodes. No additional pseudo-instructions are needed on this family.

Go to the previous, next section.