DMA Channel Assignments
Part III: Appendixes
483
DMA Channel Assignments
Direct Memory Access (DMA) allows some devices to transfer
data to and from memory at high speeds, without using the CPU.
Such devices are each assigned a unique DMA channel. The com-
puter has two DMA controllers with four channels on each con-
troller, a total of eight DMA channels.
The following table lists the computer's DMA channel assign-
ments.
Input/Output Port Address Assignments
The CPU accesses input/output devices, such as modems, by read-
ing from them or writing to them. Each command to read or write
must specify the address (in memory) for the port. Each device
that communicates with the CPU must have a unique I/O port
address.
DMA
Use
Notes
0
Reserved
Choice for Sound System
1
Sound System
Choice for ECP
2
3 1/2” diskette drive
Choice for ECP
3
ECP
Choice for diskette drive,
ECP, or Sound System
4
Cascade from DMAC 1
5
Reserved
6
Reserved
7
Reserved
000-book.bk : 82-resrc.fm5 Page 483 Wednesday, May 15, 1996 4:15 PM