Configuring DMA and IRQ 9-1
9. CONFIGURING DMA and IRQ
9.1 DMA Channels Allocation
The TEK-AT4L
PLUS
supports seven Direct Memory Access channels: Channel 0 is
reserved for the DRAM refresh. Channel 4 is used to cascade channels 0 through 7 to the
microprocessor, and Channel 2 is reserved for the floppy controller.
TABLE 9-1:
8237 Controller Table
DMA 0
Refresh
DMA 1
Available
DMA 2
Floppy controller
DMA 3
Available
DMA 4
Cascade controller # 1
DMA 5
Available
DMA 6
Available
DMA 7
Available
9.2 Allocating IRQ Lines
Two 8259 interrupt controllers handle the interrupts on the TEK-AT4L
PLUS
. Six
interrupt lines are directly linked to the keyboard controller, timer, the real-time clock,
both serial ports and the parallel port. A seventh interrupt line (IRQ12) is used for the
PS/2 MOUSE but the mode can be made available by the W19A jumper.
TABLE 9-2:
8259 Controller Table
CONTROLLER # 1
CONTROLLER # 2
IRQ 0
Timer 0
IRQ 8
Real-time clock
*
IRQ 1
Keyboard
IRQ 9
Available
IRQ 2
Cascade controller # 2
IRQ 10
Available
IRQ 3
COM 2
*
IRQ 11
Available
IRQ 4
COM 1
*
IRQ 12
PS/2 Mouse/Available
IRQ 5
Available
IRQ 13
Available
IRQ 6
Floppy controller
IRQ 14
Fixed disk
*
IRQ 7
LPT 1
*
IRQ 15
Available
* All functions marked with an asterisk (*) can be disabled.
Summary of Contents for TEK-AT4L Plus
Page 7: ...PRODUCT DESCRIPTION 1 PRODUCT OVERVIEW 2 ONBOARD SUBSYSTEMS...
Page 9: ...Product Overview 1 2 TEK AT4LPLUS Block Diagram...
Page 26: ...Installing Devices 6 3 CONNECTOR LOCATION...
Page 35: ...Setting Jumpers 8 3 JUMPER LOCATIONS...
Page 36: ...Setting Jumpers 8 5 TABLE 8 1 Jumper Settings W1 W11...
Page 37: ...Setting Jumpers 8 6 TABLE 8 2 Jumper Settings W12 W19 W26...
Page 38: ...Setting Jumpers 8 7 TABLE 8 3 Jumper Settings W20 W25 SW1 SW2...
Page 41: ...APPENDICES A PRODUCT SPECIFICATIONS B BOARD DIAGRAMS C CONNECTOR PINOUTS...
Page 43: ...Board Diagrams B 1 B 1 TEK AT4LPLUS Assembly Diagram Top View...
Page 44: ...Board Diagrams B 3 B 2 TEK AT4LPLUS Mounting Holes...
Page 45: ...Board Diagrams B 5 B 3 TEK AT4LPLUS Mechanical Specifications...