🚀 go-pugleaf

I am looking for information on the protocol used to implement the
PC-LINK service (it is like Compuserve, the Source, etc.).  This service
can only be accessed by using their program PCLINK and they implement
some type of protocol to talk to their host system.  If you know
anything about the protocol used please contact me. 


What I know:

(1) The service is based on checksumed (I'm guessing) sequenced packets. 
The packets always start with a Z (0x5a) and end with a <CR> (0x0d).  As
far as I can tell the packet has a 7 byte header where the first byte is
a Z, the next four bytes look like they might be a check function, and
the next two bytes are send and receive sequence numbers.  Here are some
examples:
                    5a010e2109421c260d
                    5a710311017f7f240d
                    5a5102010b2818260d
                       ^^  ^^
(2) It is interesting to note that of the four bytes that look like a
check function that the nibbles marked are always a "10" (see above).  I
have looked at quite a few frames and have seen no violations of this. 


_______________________________________________________________________________
           __                                    David D. Dorfmueller
          /  )         _                         Intergraph Corporation
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