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MODE REGISTER
2
0 -
BIT NUMBER
r-~.-.-.--r-.-.-'
00
CHANNEL 0 SELECT
01
CHANNEL 1 SELECT
10
CHANNEL 2 SELECT
II
CHANNEL 3 SELECT
00
VERIFY TRANSFER
01
WRITE TRANSFER
10
READ TRANSFER
11
ILLEGAL
0
AUTO INITIALIZATION DISABLE
AUTO INITIALIZATION ENABLE
0
ADDRESS INCREMENT SELECT
ADDRESS DECREMENT SELECT
00
DEMAND MODE SELECT
01
SINGLE MODE SELECT
10
BLOCK MODE SELECT
11
CASCADE MODE SELECT
Figure 2-10 DMA Command and Mode Registers (cont'd)
REQUEST REGISTER
7
6
5
4
3
2
o -
BIT NUMBER
'---~V""'-_...J
L-y-J
L{~~
10
11
DON'T CARE
'-----{
~
SELECT CHANNEL 0
SELECT CHANNEL 1
SELECT CHANNEL 2
SELECT CHANNEL 3
RESET REQUEST BIT
SET REQUEST BIT
SOFTW ARE REQUESTS WILL BE SERVICED ONLY IF THE CHANNEL IS IN BLOCK MODE.
Figure 2-11 DMA Request and Mask Register
Processor PCB
2-17
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