Apple Lisa - Serial Interfaces

Confidential
Lisa Hardware Reference Manual
THE SERIAL INTERFACES
The Lisa has two built-in RS232-C serial communication ports. Both
ports can support local asynchronous commnuications at speeds up to
19.2 Kbaud. In addition, port 1 conforms to RS232-C type D
specifications, permitting full modem control with either synchronous
or asynchronous protocols.
The serial logic is implemented with a NEC 7201 dual channel
communication interface. Refer to the 7201 data sheet for complete
information about the operation of the chip. Note that autovectors
are used so you do not need to program the 7201 to supply the
interrupt vectors.
The 7201 has neither an internal baud rate generator, nor a Ring
Indicator input. The baud rate generator is provided by the serial
interface. The Ring Indicator input is brought into the channel B
DCD (Data Carrier Detect) line where it must be decoded by software.
The DCD line can be programmed to produce an interrupt whenever there
is a transition on that line.
SERIAL INTERFACE LINES
Signal Name
Description
RS-232 Pin II
Channel A Channel B
, ________ • ___________________ n ____________________ ,_ •• ___________ _
TxD
RxD
RTS
CTS
DTR
DCD
RI
!xC
RxC
TEXT
DSR
Transmit Data
Received Data
Reques t
To Send
Clear To Send
Data Terminal Ready
Data
Carrier Detect
Ring Indicator
Transmit Clock Input
Receive Clock Input
Transmit Clock Output
Data Set Ready
2
3
4
5
20
8
22
15
17
24
2
3
4
20
6
Both channels are set up to be the Data Terminal Equipment (DTE) end
7-Jul-81
of the communications system. To connect other DTE devices to the Lisa,
you need a modem eliminator (a null modem). The Apple II/ null modem
(590-0029-00) with a communciations card cable can be used to connect
the Lisa to a Qume printer through channel B.
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