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TITLE  : LapLink cable specifications.
DATE   : 18-08-1994
AUTHOR : C. Holz.
EMAIL  : cholz@wilbur.mbark.swin.oz.au

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Serial link cable.
------------------
Make a serial cable with two female DB25 (or female RS232) connectors.
Seven connections are required.  Wire the cable as follows:

    9 pin       25 pin          25 pin      9 pin
    =====       ======          ======      =====
    pin 2       pin 3   <--->   pin 2       pin 3  (Receive-Transmit)
    pin 3       pin 2   <--->   pin 3       pin 2  (Transmit-Receive)
    pin 4       pin 20  <--->   pin 6       pin 6  (DTR---DSR)
    pin 5       pin 7   <--->   pin 7       pin 5  (Grd---Grd)
    pin 6       pin 6   <--->   pin 20      pin 4  (DSR---DTR)
    pin 7       pin 4   <--->   pin 5       pin 8  (RTS---CTS)
    pin 8       pin 5   <--->   pin 4       pin 7  (CTS---RTS)

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Parallel link cable.
--------------------
Make a parallel wiring box with male DB-25 connectors at both ends.
Fifteen connections are required.

    25 pin          25 pin
    ======          ======
    pin 01  <---->  pin 01
    pin 02  <    >  pin 15
    pin 03  <    >  pin 13
    pin 04  <    >  pin 12
    pin 05  <    >  pin 10
    pin 06  <    >  pin 11
    pin 10  <    >  pin 05
    pin 11  <    >  pin 06
    pin 12  <    >  pin 04
    pin 13  <    >  pin 03
    pin 14  <---->  pin 14
    pin 15  <    >  pin 02
    pin 16  <---->  pin 16
    pin 17  <---->  pin 17
    pin 25  <---->  pin 25  (Grd---Grd)

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Null modem plugs.
-----------------
The best way I have seen to make you own laplink cables is to purchase two DB25
wiring boxes.  One Male to Male, the other Female to Female.
The Male to Male is wired up as a Parallel null modem, and the Female to Female
as the Serial null modem.
All that is needed then is a standard serial EXTENSION cable (Male to Female
DB25).
By plugging the Serial Null modem into the Male end, you have a full serial
laplink cable with Female to Female connectors.
Or visa-versa by plugging the Parallel Null modem into the Female end, you have
a full parallel laplink cable with Male to Male connectors.
The only single problem with this is, that the serial null modem will not plug
into a standard RS232 9 pin plug.  This can be overcome by purchasing one or
two convertors (9 pin Female to 25 pin male).

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Laplink extension cable.
------------------------
Instead of forking out large amounts of money for an extension cable for your
current cable or for the null modem, and extension cable can be made from the
following specs.
Make a cable with one female and one male DB-25 connector at either end.
Fifteen wires are required.  Four jumper wires are required between pins.

    25 pin          25 pin
    ======          ======
    pin 01          pin 01
    pin 02          pin 02
    pin 03          pin 03
    pin 04          pin 04
    pin 05          pin 05
    pin 06          pin 06
    pin 07 / 25     pin 07 / 25
    pin 10          pin 10
    pin 11 / 20     pin 11 / 20
    pin 12          pin 12
    pin 13          pin 13
    pin 14          pin 14
    pin 15          pin 15
    pin 16          pin 16
    pin 17          pin 17

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Information.
------------
These specifications are complete to my knowledge.  The specs allow in laplink
what is known as Accelerated Transfer, which is much faster than Standard
transfer.

These cable have been fully tested for DOOM.  To play DOOM over parallel link,
it is necessary to acquire a file called DOOMPAR.ZIP produced by an author
called Andrew who produced a serial driver for use with DOOM r1.1.
One warning with using the parallel connection with DOOM, that some computers
do not work and a connection is never found.

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