z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 105

• Manufacturer Part Number: z80189
• Description: Z80180, Z8s180, Z8l180 Mpu Operation
• Manufacturer: ZiLOG Semiconductor

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UM005003-0703
Z8018x
Family MPU User Manual
DMA Controller (DMAC)
3. Refresh cycles are suppressed during SLEEP mode. If a refresh cycle
4. Regarding (2) and (3), the refresh address is incremented by one for
The Z8X180 contains a two-channel DMA (Direct Memory Access)
controller which supports high speed data transfer. Both channels
(channel 0 and channel 1) feature the following capabilities:
•
•
•
is requested during SLEEP mode, the refresh cycle request is
internally latched (until replaced with the next refresh request). The
latched refresh cycle is inserted at the end of the first machine cycle
after SLEEP mode is exited. After this initial cycle, the time at which
the next refresh cycle occurs depends on the refresh time and has no
timing relationship with the exit from SLEEP mode.
each successful refresh cycle, not for each refresh request. Thus,
independent of the number of missed refresh requests, each refresh
bus cycle uses a refresh address incremented by one from that of the
previous refresh bus cycles.
Memory Address Space
Memory source and destination addresses can be directly specified
anywhere within the 1024KB physical address space using 20-bit
source and destination memory addresses. In addition, memory
transfers can arbitrarily cross 64KB physical address boundaries
without CPU intervention.
I/O Address Space
I/O source and destination addresses can be directly specified
anywhere within the 64KB I/O address space (16-bit source and
destination I/O addresses).
Transfer Length
Up to 64KB are transferred based on a 16- bit byte count register.