Hardware manual

1
Microcomputer Technical Q&A
Q&A No.: QAH8S-001
Category: CPU
Subject: Use of General Registers
Question
Is it possible to use a mix of 8-bit, 16-bit, and 32-bit general registers?
Answer
Yes. Individual registers can be used in any way desired, as shown below.
E0
E2
E4
E5
E6
R0H
R2H
R6H
R0L
R2L
R4
R5
R6L
ER1
ER3
ER7 (SP)
Example:
However, note that ER7 is used implicitly as the SP.
Applicable Products
Applicability Series Applicability Series Applicability Series
Yes Entire H8S Series H8S/2655 H8S/2350
H8S/2355 H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —