Dma; System Interrupts - Epson MR Series Technical Reference Manual

DMA

The IM-800 supports seven DMA channels. Channels 0, 1, 2, and 3 provide 8-bit data transfers;
channels 4, 5, 6, and 7 provide 16-bit data transfers. The IM-800 uses channel 2 for the floppy
disk drive controller and releases the other channels to the other devices. The following table
lists the DMA channel allocation.
DMA channels
Controller
DMA1 8 bits
DMA2 16 bits
* When LPT1 is in ECP mode, use one of these channels.

System Interrupts

The system connects 2 8259A-equivalent interrupt controllers in cascade and has 15 levels of
interrupts, besides NMIs. The following table shows the application for each interrupt. Change
the system interrupts with the BIOS setup program or Plug & Play function.
System interrupts
Controller 1 Controller 2
IRQ0
IRQ1
IRQ2
IRQ8
IRQ9
IRQ10
IRQ11
IRQ12
IRQ13
IRQ14
IRQ15
IRQ3
IRQ4
IRQ5
IRQ6
IRQ7
NMI
1
* PCI (for example, network) is automatically set through the detection of the unused interrupt level. If Serial port 3/
4 is used with Windows, use an unused interrupt level. If Serial port 3/4 is used with DOS, Serial port 3 is set to IRQ11
and Serial port 4 is set to IRQ10 automatically.
2
* Changes are not possible when the device is in use, but can be cleared when not in use.
3
* This can be set to "Not used" in the BIOS setup, but the IRQ is not released.
3-2 Hardware Specifications
Channel Application
0 (Spare)
1 (Spare*)
2 Floppy disk drive controller
3 (Spare*)
4 Controller 1 cascade
5 (Spare)
6 (Spare)
7 (Spare)
Application
Timer
Keyboard
Controller 2 cascade
RTC
1
Not used *
Not used *1
1
Not used *
Mouse
Numerical operation coprocessor
IDE controller (primary)
IDE controller (secondary)
Serial port 2
Serial port 1
1
Not used *
Floppy disk controller
Parallel port 1
I/O error check
Changeable?
NO
NO
NO
NO
OK
OK
OK
NO
NO
2
*
2
*
OK
OK
OK
3
NO *
OK
NO
Rev. I