Epson EISA Tower Product Information Manual - Page 5

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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

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

depends upon the type of video adapter card installed.

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