Apple III Port C: RS-232-C Pinouts & Configuration (10/94)
The following table explains how use System Utilities to configure the driver for the RS-232 port (Serial Interface and Serial Card III). Remember to set the slot number on the Serial Card III driver.
This article has been archived and is no longer updated by Apple.
Data Configuaration Blocks:
Data Configuration
Block Address: $00
Baud rate:
110 $03
134.5 $04
300 $06
600 $07
1200 $08
1800 $09
2400 $0A
4800 $0C
9600 $0E
Data Configuration
Block Address: $00 $01
Data Format:
Bits Parity
8 none $00
7 odd $22
7 even $26
7 MARK $2A
7 SPACE $2E
6 odd $42
6 even $46
6 MARK $4A
6 SPACE $4E
Data Configuration * * *
Block Address: $00 $01 $02 $03 $04 $05 $06 $07 $08 $09 $0A $0B
Comm Protocol:
none $00
XON/XOFF $80 $13 $11 $DF $84 $00
ENQ/ACK $40 $05 $06 $50 $00
ETX/ACK $40 $03 $06 $50 $00
HW Handshake $00 $DF $84 $80
* $02 - Delay after CR
* $03 - Delay after LF
* $04 - Delay after FF
Delays (bytes $02, $03, and $04)
Using this driver to connect to a printer may require that you set delay times while the printer advances to a new line or the top of a new page. These delays are given in the range $00...$FF characters. The RS-232 driver will wait for the time taken to transmit the amount of character specified before it sends the following character.
Pinouts:
DB-25
Connector Signal Name
1 ...... Shield Ground
2 ...... Transmit Data (Tx)
3 ...... Receive Data (Rx)
4 ...... Request to send (RTS)
5 ...... Clear To Send (CTS)
6 ...... Data Set Ready (DSR)
7 ...... Signal Ground
8 ...... Data Carrier Detect (DCD)
20 ...... Data Terminal Ready (DTR)
Serial Card III has a modem eliminator button; when this button is "in", the above pinouts are correct. If the button is "out", this has the effect of a modem eliminator cable being installed. (For more information on modem eliminator cables, search this database for MODEM AND ELIMINATOR.)
Article Change History:
12 Oct 1994 - Reviewed for technical accuracy.
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Last Modified: Feb 19, 2012