LSI Logic Confidential
8-28
Host Slave Interface
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
least significant and the upper four bits of this register must be zero.
During burst reads, the three least significant bits must be zero.
8.8.3
Master DMA NextAddress Register (Cbus Addr: 0x6F004)
This register at control bus address 0x6F004 specifies the SDRAM
address for master DMA data. When GO is set, this register specifies the
starting SDRAM address where master DMA data will be stored or read.
As DMA data is transferred, this register is updated automatically by
hardware to point to one byte after the last transferred byte in SDRAM.
This register is read by microcode to determine how many bytes of DMA
information have been transferred. The two least significant and the
upper four bits of this register must be zero.
8.8.4
Master DMA StopAddress Register (Cbus Addr: 0x6F008)
This register at control bus address 0x06F008 specifies the transfer stop
SDRAM address for master DMA data. When the Next Address reaches
the value in this register and the DMA data has been transferred to
SDRAM or the system, the DMA transfer is completed and the GO bit is
cleared. This register can be reloaded while a DMA transfer is active to
extend the length of a DMA operation. In a normal operation, this register
should never be greater than or equal to the address value stored in the
Limit Address register. The two least significant and the upper four bits
of this register must be zero.
While a DMA transfer is active, the Stop Address register should not be
reloaded with the address value of the Next Address register. It is
possible that the Next Address may hit the old Stop Address when the
Stop Address Register is reloaded with a new value.
Note:
Reloads of the stop address must be synchronized with
DMA completion detection so that the DMA operation is not
restarted after the GO bit is cleared or a completion
interrupt is generated.
8.8.5
Master DMA BaseAddress and LimitAddress Registers
(Cbus Address: 0x6F00C and 0x6F010)
The master DMA base address register at control bus address 0x6F00C
specifies the SDRAM address for the beginning of the master DMA
Содержание DMN-8600
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