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DMA Controller
Direct memory access (DMA) improves system performance by
allowing devices to access the system memory directly. This ability is
provided by two 82C37-compatible direct memory access controllers
(DMACs) contained in the 82357. The seven independent 32-bit DMA
channels are listed in the table below along with their associated
DMA controller and their device assignments.
DMA request level
Level
DRQ 0 (CTRL1)
DRQ 1 (CTRL1)
DRQ 2 (CTRL1)
DRQ 3 (CTRL1)
DRQ 4 (CTRL2)
DRQ 5 (CTRL2)
DRQ 6 (CTRL2)
DRQ 7 (CTRL2)
Hardware interrupt (IRQ) map
Interrupt
IRQ0
IRQ1
IRQ2
IRQ3
IRQ4
lRQ11
IRQ12
IRQ13
IRQ14
lRQ15
EISA Series Computers
Spare
,
Diskette drive controller
Spare
(Cascade for CTRL1)
Spare
Spare
Spare
System timer
Keyboard
Cascade interrupt
Serial port 2
Serial port 1
System Memory Map
Use of the memory areas for video memory and the video BIOS
l
depends upon the type of video adapter card installed.
1/92
EISA Series Tower
Tower-5
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