ZiLOG Z-80 SIB User Manual page 15

3.3
Port Address Selection
The SIB has
20
I/O
ports associated with
it;
12
for the three
CTCs, and
8
for the
four USARTs, To
position these
20
ports
in the I/O
address space, jumpers
at Jl and J4 are
required
(see
schematics, page
3).
The user can place the ports in
one
of
eight address ranges, with each range having
32
available ports.
Table 3.3.1 below shows
the
jumper
connections corresponding
to
each address
range:
ADDRESS RANGE
J4
JUMPERS
00 to IF
5-16, 1-7, 3-6
20 3F
5-15, 1-7, 3-6
4tK
5F
5-16, 2-7, 3-6
60
7F
5-15, 2-1, 3-6
80 9F
5-16, 1-7, 4-6
AO BF
5-15, 1-7, 4-6
CO OF
5-16, 2-7, 4-6
so FF
5-15, 2-7, 4-6
TABLE 3.3.1 Port Address Range
Jumpers applied
to
Jl will
position each
1/0 port into
a
unique address within the range selected.
Each of the
device
select lines, GPM- through GPT-,
is
connected
to
one of the
port decoder outputs, GPO- through GP7-.
Tables 3.3.2 and
3.3.3 show the corresponding jumper connections
at Jl:
DEVICE SELECTS DEVICE
JUMPER
Jl
GPM- USART
0,
1
14
GPN- USART
2, 3
13
GPR- CTCO
12
GPS- CTCl
11
GPT- CTC2
10
TABLE 3.3.2 Device Select
7