6. DMA Controller
ÛZIATECH
48
PROGRAMMABLE REGISTERS
Each DMA controller is managed through the 16 I/O port addresses shown in the table
"
" on the following page. Page registers extend the 16-
bit DMA address to the full 24-bit address space available on the ZT 8907. I/O port
addressing for the DMA page registers is given in the "
table below.
Note:
The ZT 8907 only supports DMA into the lower 16 Mbytes of DRAM memory and
does not support DMA Extended Page I/O Port addressing. Windows 95 users with
more than 16 Mbytes of RAM must ensure that their DMA controller properties are set
to restrict DMA transfers to memory below 16 Mbytes. Windows 95 may not auto-detect
these settings.
DMA Page I/O Port Addressing
Address Register
Operation
87h
Channel 0 A16-23 Address
Read/Write
83h
Channel 1 A16-23 Address
Read/Write
81h
Channel 2 A16-23 Address
Read/Write
82h
Channel 3 A16-23 Address
Read/Write
8Bh
Channel 5 A16-23 Address
Read/Write
89h
Channel 6 A16-23 Address
Read/Write
8Ah
Channel 7 A16-23 Address
Read/Write
