Re: HELP:Trouble in connecting btw GS and PC

[Rubywand <rubywand@swbell.net>]

leo Jang writes ...
> 
> Hi, there...I'm stucked while I'm trying to transmit data from PC to GS at
> the first step...please help me out..
> 
> I've got a ADT-GS and I tried to find adapter to connect GS serial cable to
> PC side COM port...but, hard to find such adapter around my area still...So,
> I decided to make one for myself..
> 
> Does anybody know connection spec(info to connect lines) between GS serial
> cable and PC side COM port ?
> 
> I know that Mac store is around my place..so, is there any possiblilty of
> borrowing exact adapter from Mac parts(or any modification)?
> 
> Basically, I am not sure I have high speed modem cable or not..what I've got
> is a printer cable..Is this same as that?

     A printer cable is not a modem cable. It swaps around some signals so that
it acts something like a NULL modem cable-- i.e. a modem cable plus a NULL
modem adaptor. I have not tried using a printer cable in place of a high-speed
modem cable + a NULL modem adaptor and do not whether or not it will work.
(Anyway, our IIgs printer cable is for the Imagewriter II, so it ends in a plug
which is hard to match up with a PC.) 


     Here is info on IIgs high-speed cable:

View is looking into the cable connector/plug at the pins. 

Male Mini-Din 8             RS-232 Male Dsub-25M 

   6  7  8           01 02 03 04 05 06 07 08 09 10 11 12 13 
   3 4   5            14 15 16 17 18 19 20 21 22 23 24 25 
    1  2 

DIN-8    Dsub-25M   Signal Discription 

  3        2        TD  (Transmit Data) 
  5        3        RD  (Receive Data) 
  4,8      7        GND (Ground) 
  2        5        CTS (Clear to Send) 
  1        4,20     RTS & DTR (Ready to Send and Data Term Ready) 
  7        8        DCD (Data Carrier Dectect) 


     You can use an Ohm meter to check your cable to see if it matches the
pinout shown.

     According to posts by some users, a Mac modem cable with the Mini-DIN 8
plug is the same as a GS high-speed cable. One thing you need to be sure of is
having a plug on the other end that will connect to an NULL modem adaptor. (The
25-pin Dsub male plug is fairly standard.)



     Below is info on a NULL modem adaptor:

     A NULL modem is two Dsub 25-pin female sockets (call them "A" and "B")
wired back-to-back as follows ... 

 Socket-A  Socket-B 

    1      -> 1 
    2      -> 3 
    3      -> 2 
    4 & 5  -> 8 
    6 & 22 -> 20 
    7      -> 7 
    8      -> 4 & 5 
   20      -> 6 & 22 
  

     A Dsub-25 female connector viewed from the front 
 ,----------------------------------------. 
 \ 13 12 11 10 09 08 07 06 05 04 03 02 01 / 
  \  25 24 23 22 21 20 19 18 17 16 15 14 / 
   `------------------------------------' 
  

     If you can find a couple old-style Dsub25 plug casings, the sockets can be
mounted and the casings can be glue-gunned together to make a nice compact
unit. 

     For Apple2-PC (or Mac, etc.) transfers, you plug the modem cable from the
Apple II into one side of the NULL modem and the modem cable from the PC into
the other side. If the PC has a 9-pin serial port connector, use a 9-to-25
adaptor cable to connect to the NULL modem. Similarly, for Mac users, if the
Mac cable has a special connector, use a converter to a male Dsub-25M connector
for plugging into the NULL modem. 


     The Mac store you mention probably sells a NULL modem adaptor. Radio Shack
may still sell one, too.

     As with the modem cable, you want 'everything to connect' without having
to look around for all sorts of plug adaptors.


  [Modem to net] 
       | 
   modem cable 
      COM1 
  ____ |______                                        ____________ 
 |  PC        |                                      |  Apple II  | 
 |  running a |    COM2                              |  running a | 
 |  telecom   | <--modem--> [NULL modem] <--modem--> |  telecom   | 
 |  program   |    cable    [ adaptor  ]    cable    |  program   | 
 |____________|                                      |____________| 
  

     If you are going to connect to a PC, you need a NULL modem adaptor which
will, first, connect to your IIgs modem cable. Then, it has to connect to the
PC serial port you want to use OR to a modem cable connected to the PC serial
port.

     9-pin PC serial ports are fairly common. So, you may have a 25-9 cable
going from the NULL modem adaptor to the PC COM port.



Rubywand