[HECnet] native Dup sync line revisited --> preliminary tests reveals problems

[Johnny Billquist]

On 2021-12-13 01:23, Paul Koning wrote:
> 
> 
>> On Dec 12, 2021, at 6:49 PM, Johnny Billquist <bqt at softjar.se> wrote:
>>
>> By the way. The logs that were included early on complained about checksum errors, but looked like they understood things pretty fine otherwise.
>>
>> Could there be some error in the CRC calculation in simh compared to what DEC is doing? I didn't fancy computing the CRC to verify if it was correct, but I guess someone could do that?
> 
> I did, the error message is correct.  I have a CRC (in PyDECnet) that's been tested against the software DDCMP in RSTS, which in turn has been tested against a DMC.

Interesting. So the CRC is indeed incorrect. I wonder what generated the 
CRC then, or how it got corrupted. Because the DDCMP header for sure 
looked perfectly correct. I did decode that much.

Which would suggest that it's just a badly generated CRC on the sender side.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol