Specifications

DMA Controller (V40)
PROGRAMMABLE REGISTERS
The DCU occupies 16 consecutive I/O port addresses. Of those 16
addresses, 12 are used by the programmer to access DCU functions
and 4 are reserved. Table 9-1 lists the address of each of the registers
relative to a programmable base address. The base address is selected
with the OPHA and DULA V40 configuration registers; see page 6-5
for details.
Table 9-1
DCU Register Addressing.
Address Register Operation Page Number
Base + 0 DICM Write 9-8
Base + 1 DCH Read/Write 9-8
Base + 2 DBC/DCC-low Read/Write 9-10
Base + 3 DBC/DCC-high Read/Write 9-10
Base + 4 DBA/DCA-low Read/Write 9-11
Base + 5 DBA/DCA-middle Read/Write 9-11
Base + 6 DBA/DCA-high Read/Write 9-11
Base + 7 Reserved -- --
Base + 8 DDC-low Read/Write 9-12
Base + 9 DDC-high Read/Write 9-12
Base + A DMD Read/Write 9-13
Base + B DST Read 9-15
Base + C Reserved -- --
Base + D Reserved -- --
Base + E Reserved -- --
Base + F DMK Read/Write 9-16
9-7