ZiLOG Z-80 SIB User Manual page 65

Sheets
5, 6,
7,
8
Sheets
5, 6, 7,
and
8
show the four USARTs and their
associated I/O buffers
and jumper areas.
USARTs
0, 1,
and
2
are
configured
as
RS232 interfaces while USART
3
may
be
either
an
RS232
or
20mA current-loop interface.
The transmit and receive clocks are strapped
at J2 and
may
be
generated externally
or
by CTC
0.
Sheet
9
Sheet
9
contains
the
on-board oscillator
and divider
counters which produce clocks
for the
CTC USART clock
generator (Sheet
2)
.
External RS232-level clocks are
buffered
by A43 and are made
available to the
USARTs
at
Jumper
J2.
5.2 SIB
Specifications
SERIAL
I/O:
Four serial input and four serial output channels
SERIAL
MODES:
Synchronous
or
asynchronous using virtually
any
serial protocol.
SERIAL INTERFACE:
CHANNEL INTERFACE
CONTROL INTERFACE:
TTL interface with
MCZ series data, address,
and
control signals.
I/O
PORT ADDRESSING:
20
jumper selectable I/O ports.
1
2
3
RS232
RS232
RS232
RS232 OR 20MA current loop
57