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Mad With Macintosh

 

Modem Cable Pinouts

 

 

 

 The pin outs are not the same between different modem cables. Also note

there is a difference between a high speed modem cable, such as would be

supplied with a V90/Flex modem, and an older specification modem cable.

There is no standardisation. Typical arrangements:

 

Apple Modem Port

 

     8 7 6
     5 4 3
      2 1

 

Apple        Hayes
HSK1  2  -  5  CTS
HSK0  1  -  20 GND
TXD-  3  -  2  TXD
GND   4  -  7  GND
RXD   5  -  3  RXD
TXD+  6     NC
GPI   7     NC
RXD+  8     1  GND

  9 way

1 2 3 4 5
 6 7 8 9


Apple to  typical  9 Way

 2 -  1&8 CTS
 1 -  4 GND
 3 -  3 TXD
 4 -  5 GND
 5 -  2 RXD

Apple to typical Apple Modem 
1 - NC
2 - 5 CTS
3 - 3 TXD
4 - 5 GND
5 - 2 RXD


25 way

1  2  3  4  5  6  7  8  9  10  11  12  13 

   14 15 16 17 18 19 20 21 22 23 24 25

 

Typical wiring for Data Terminal Equipment, (DTE) and Data Communication

Equipment (DCE):

 

DTE                    DCE

2 Transmit Data        2 Receive Data
3 Receive Data         3 Transmit Data
4 Request to Send      4 Clear to Send
5 Clear to Send        5 Request to send
6 Data Set Ready       6 Data Termimal Ready
7 Ground               7 Ground
20 Data Terminal Ready 20 Data Set Ready

 

 

Typically a computer will be DTE and a modem will be DCE, but this is not

always so. DTE wiring connects to DCE wiring as above. If you have a DTE to

DTE cable, and an interface requiring a DTE to DCE, or vice versa, then it

won't work.

 

So that's the explanation.

 

You can check which pins go to where using a meter, or a small bulb

connected to a battery.

 


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