Re: IIc Modem cable pinouts?

[dempson@swell.actrix.gen.nz (David Empson)]

In article <931119.83007.BILL90@delphi.com> Bill Green <BILL90@delphi.com> writes:
> I've got a problem with constructing a modem cable for a IIc.  The information
> I've  gotten from Apple and the files on cco.caltech.edu, all show how to
> construct a cable using a DB25 connector at the modem, and a Mini 8 at the IIc.
> Problem is, the IIc has a 5 pin connector.

Sounds like someone got the IIc and IIc+ confused.  The IIc+ has a
Mini-DIN-8.  Here is the pinout of the IIc's serial port.

Looking at the back of the IIc:

5           1
  4       2
      3  

1  DTR (flow control out from IIc)
2  TxD (data out from IIc)
3  Ground
4  RxD (data in to IIc)
5  DSR (flow control in to IIc)

The cable you use to connect to the modem will vary, depending on what
type of modem you have, and which flow control functions you require.

The following is a standard IIc modem cable, with no data handshaking.
If the IIc drops DTR, the modem will hang up or enter command mode
(depending on its AT&D setting).  The IIc's incoming flow control line
will indicate the modem's presence (DSR).

IIc (DIN-5)      Modem (DB-25)
1 DTR            20 DTR
2 TxD            2  TxD
3 Ground         7  Ground
4 RxD            3  RxD
5 DSR            6  DSR

An alternative is to connect the IIc's DSR line to the modem's DCD pin
(8), which allows the IIc to detect whether the modem has carrier.

A third alternative should be used with a high-speed modem which
requires hardware handshaking.  Connect IIc's pin 1 (DTR) to modem pin
4 (RTS) and IIc pin 5 (DSR) to modem pin 5 (CTS).


The exact cable you use will depend on the communications software (and
device driver, if appropriate).
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz                                                
Snail mail: P.O. Box 27-103, Wellington, New Zealand