C
ONFIGURE
& I
NSTALL
B
OARD
2-5
I/
O
P
o
rt
A
d
d
re
ss
S
p
a
ce
f
o
r
P
C
-b
a
se
d
A
rc
h
it
ec
tu
re
s
B
a
se
I
/O
A
d
d
re
ss
U
sa
g
e
Figure 2-1
Host/DSP Communications over ISA/104/STD Bus
Communication occurs in 2 steps.
1.
First the address is set by writing to 0x300 and 0x301 with two 8-bit writes. This “con-
nects” the ISA bus data lines to the specified location in the controller’s internal memory
map.
2.
Next, the data is read/write on addresses 0x302 and 0x303 with two 8-bit read/writes.
Host/DSP
Communications
ISA/104/STD
B
US
RAM
DSP Address Low Byte
DSP Address High Byte
DSP Data Low Byte
DSP Data Low Byte
Set/Reset DSP Flip-Flop
Clear Reset DSP Flip-Flop
H
OST
I/O S
PACE
DSP S
ERIES
C
ONTROLLER
Address
Data
A
b
lo
ck
o
f
1
/0
a
d
d
re
ss
es
Memory Window For DSP
0x300
0x301
0x302
0x303
0x304
0x305
0x309
0x30F
0x310
Host writes address to DSP
Host reads or writes data to DSP
1
2
1
2
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