The following is a list of Apple Serial Connector Pin Assignments, as well as a chart listing the major Apple cables. The information was presented in the A+ magazine, June 1986, The Right Connections, by Brian Cutter. I do not guarantee the accuracy of this information. APPLE PIN ASSIGNMENTS Listing the pin assignments and signal names of Apple computer and peripheral connectors. Pins not listed are not connected, unless otherwise noted. A. RS-232 Interfaces SUPER SERIAL CARD -- DB25 1 Fame Ground 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Request to Send (RTS) 5 Clear to Send (CTS) 6 Data Set Ready (DSR) 7 Signal Ground (GND) 8 Data Carrier Detect (DCD) 19 Secondary Clear to Send (SCTS) 20 Data Terminal Ready (DTR) Note: This assumes that the "jumper block" is in the MODEM position. For signal to pin configuration with the block in the TERMINAL position, refer to the SSC Operator Manual. APPLE //C SERIAL PORTS (both) -- DIN 5-pin 1 Data Terminal Ready (DTR) 2 Transmit Data (TXD) 3 Signal Ground (GND) 4 Receive Data (RXD) 5 Data Set Ready (DSR) APPLE MODEM 300/1200 -- DB9 2 Data Set Ready (DSR) 3 Signal Ground (GND) 5 Receive Data (RXD) 6 Data Terminal Ready (DTR) 7 Data Carrie Detect (DCD) 8 Frame Ground 9 Transmit Data (TXD) APPLE PERSONAL MODEM -- Mini-DIN 8-pin 1 Data Set Ready (DSR) 2 Data Terminal Ready (DTR) 3 Receive Data (RXD) 4 Signal Ground (GND) 5 Transmit Data (TXD) 6 Signal Ground (GND) 7 Data Carrier Detect (DCD) LASERWRITER -- DB25 (See RS-422 section below for LaserWriter DB-9 Connector) 1 Frame Ground 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Ready to Send (RTS) 7 Signal Ground (GND) 20 Data Terminal Ready (DTR) IMAGEWRITER I -- DB25 (See RS-422 section below for ImageWriter II Connector) 1 Frame Ground 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Request to Send (RTS) 7 Signal Ground (GND) 14 Fault 20 Data Terminal Ready (DTR) APPLE SCRIBE PRINTER -- DB25 1 Frame Ground 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Request to Send (RTS) 7 Signal Ground (GND) 20 Data Terminal Ready (DTR) APPLE DAISYWHEEL PRINTER -- DB25 1 Frame Ground 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Request to Send (RTS) 5 Clear to Send (CTS) 6 Data Set Ready (DSR) 7 Signal Ground (GND) 8 Data Carrier Detect 20 Data Terminal Ready (DTR) B. RS-422 INTERFACE MACINTOSH SERIAL PORTS -- DB9 (Old Mac 128/512) 1 Frame Ground 2 +5V *See note below 3 Signal Ground (GND) 4 Tansmit Data (TXD+) 5 Transmit Data (TXD-) 6 +12V *See note below 7 Handshake 8 Receive Data (RXD+) 9 Receive Data (RXD-) *Note: Apple Computer does not recommend using these voltages to power external devices. MACINTOSH PLUS SERIAL PORTS -- Mini DIN 8-pin 1 Handshake Output (HSKo +12V) 2 Handshake Input (HSKi) 3 Transmit Data (TXD-) 4 Frame Ground 5 Receive Data (RXD-) 6 Transmit Data (TXD+) 8 Receive Data (RXD+ IMAGEWRITER II -- Mini DIN 8-pin 1 Data Terminal Ready (DTR) 2 Data Set Ready (DSR) 3 Transmit Data (TXD-) 4 Signal Ground (GND) 5 Receive Data (RXD-) 6 Transmit Data (TXD+) 8 Receive Data (RXD+) LASERWRITER -- DB9 (See RS-232 section above for LaserWriter DB-25 Connector) 1 Ground (GND) 3 Ground (GND) 4 Transmit Data (TXD+) 5 Transmit Data (TXD-) 8 Receive Data (RXD+) 9 Receive Data (RXD-) C. SCSI INTERFACE MACINTOSH PLUS SCSI PORT -- DB25 CAUTION: Do not confuse this connector with a RS-232 Interface connector!! 1 Request (REQ-) 2 Message (MSG-) 3 I/O- 4 Reset (RST-) 5 Acknowledge (ACK-) 6 Busy (BSY-) 7 Ground (GND) 8 Data Line 0 (DB0-) 9 Ground (GND) 10 Data Line 3 (DB3-) 11 Data Line 5 (DB5-) 12 Data Line 6 (DB6-) 13 Data Line 7 (DB7-) 14 Ground (GND) 15 Carrier Detect (C/D-) 16 Ground (GND) 17 Attention (ATN-) 18 Ground (GND) 19 Select (SEL-) 20 Parity (DBP-) 21 Data Line 1 (DB1-) 22 Data Line 2 (DB2-) 23 Data Line 4 (DB4-) 24 Ground (GND) Note: The minus sign (-) after the signal name indicates an active low signal (GND), not -5V! There are no -5V on the SCSI port! APPLE CABLE GUIDE ABBREVIATIONS: SSC = Super Serial Card; 2CS = //c Serial Ports; IWR = Image Writer I; IWR2 = Image Writer II; LWR = Laser Writer; DWP = Apple Daisywheel Printer MDM = Modem 300/1200; PMDM = Personal Modem; MAC = Macintosh 128/512; MAC+ = Macintosh Plus A. APPLE II, II+, IIe CABLES 1. SSC => IWR (590-0037) (DB25 => DB25) 2. SSC => IWR2 (590-0335) (DB25 => Mini DIN 8) 3. SSC => LWR (no Apple cable available) (DB25 => DB25) 4. SSC => DWP (Identical to #1) 5. SSC => MDM (590-0121) (DB25 => DB9) 6. SSC => PMDM (590-0331)(DB25 => Mini DIN 8) 7. SSC => MAC (590-0169) (DB25 => DB9) B. APPLE IIc CABLES 8. A2C => IWR (590-0191) (DIN 5-pin => DB25) 9. A2C => IWR2 (590-0333)(DIN 5 => Mini DIN 8) 10. A2C => DWP (Identical to #8) 11. A2C => MDM (590-0192) (DIN 5-pin => DB9) 12. A2C => PMDM (Identical to #9) C. MACINTOSH CABLES 13. MAC => IWR (590-0169) (DB9 => DB25) 14. MAC => IWR2 (590-0332)(DB9 => Mini DIN 8) 15. MAC => MDM (590-0197) (DB9 => DB9) 16. MAC => PMDM (Identical to # 14) 17. MAC => Generic Modem (No Apple Cable available) (DB-9 => DB25) D. MACINTOSH PLUS (Mac II) CABLES 18. MAC+ => IWR (590-0169, with 590-0341) (Mini DIN 8-pin => DB25) 19. MAC+ => IWR2 (590-0340) (Mini DIN 8-pin => Mini DIN 8-pin) 20. MAC+ => MDM (590-0197, with 590-0341) (Mini DIN 8-pin => DB9) 21. MAC+ => PMDM (Identical to # 19) 22. MAC+ => Generic Modem (No Apple Cable available) (Mini DIN 8-pin => DB25 E. SPECIAL 23. DB25 => DB25 Modem Eliminator Cable (Apple Cable # 590-0166) 24. Mini DIN 8-pin => DB-9 Adapter (Apple Cable # 590-0341) Further REFERENCE: Kim G. House & Jeff Marble, THE PRINTER CONNECTIONS BIBLE. (Howard E. Sams & Co. Inc., 4300 W. 62nd St., Indianapolis, IN 46268) Carolyn Curtis & Daniel L. Majhor, THE MODEM CONNECTIONS BIBLE. (Howard E. Sams & Co. Inc., 4300 W. 62nd St., Indianapolis, IN 46268) MICRO MATCH (Command Computer Corporation, 36 Columbia Terrace, Weehawken, NJ 07087) THE APPLE INTERFACE MANUAL (Apple Computer, Inc., 20525 Mariani Avenue, Cupertino, CA 95014), Date: Wed, 25 Feb 87 12:14:10 EST MICRONET OFFERS A SIMPLE SCSI TERMINATION SOLUTION FOR THE MACINTOSH SE & II FAMILY MicroNet Technology has released a "Mother Board" Terminator that easily installs in the internal SCSI port of the Macintosh when an internal hard disk drive is not present. Suggested retail price for the MBT is $35.00 and is available through MicroNet dealers. The specification for SCSI states that each end of the bus must be terminated. In many cases an internal hard drive is installed which provides termination for omly the front end of the bus. Termination issues have become more critical with the advent of faster CPU's, such as the Macintosh IIci. If a user elects to install only an external hard drive, especially one that employs a fast SCSI chip set, the bus will not be properly terminated and the system may refuse to boot or may become unreliable. The lack of an option for terminating the mother board of a Macintosh when an internal hard drive is "absent" has caused many technicians hours of grief and is a point that many overlook. It is not an obvious problem and should have been better accommodated in the original design of the computer. "Calls to our technical support department concerning termination issues have steadily increased since the release of the Macintosh IIcx and IIci". "Frustration led to the development of the Mother Board Terminator". "We simply could not reliably test external hard drive systems on a Macintosh IIci without an internal hard drive to provide termination". "We have had our dealers call Apple Technical Support to verify the need to terminate the mother board only to get an indefinite answer". "Our dealer response is positive to the terminator and it has solved many problems", stated Charles F. McConathy, President of MicroNet. MicroNet specializes in data storage systems and sells through dealers and distributors worldwide. For data sheets and dealer information please contact MicroNet Technology, Sales Department, 20 Mason, Irvine, CA 92718. Tel: (714) 837-6033