Hardware manual

Microcomputer Technical Q&A
82
Q&A No.: QAH8S-209
Category: DMAC
Subject: Short Address Mode and Full Address Mode
Question
What is the difference between the DMAC’s short address mode and full address mode?
Answer
The DMAC requires specification of the source address and destination address in order to
perform data transfer. In full address mode, both of these addresses are specified as 24-bit
addresses, whereas in short address mode, one is specified as a 24-bit address and the other as a
16-bit address. H'FF is written in the upper 8 bits of the 16-bit address. In short address mode,
whether the 16-bit specification is to be used for the source or the destination address can be
selected with a register setting.
If transfer is to be performed by means of internal interrupts in full address mode, setting a block
size of 1 in block transfer mode results in the same operation as for sequential mode in short
address mode.
Applicable Products
Applicability Series Applicability Series Applicability Series
Entire H8S Series Yes H8S/2655 Yes H8S/2350
H8S/2355 Yes H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —