I ma rusty on this, been almost 50 years since I worked on the DP8EP
aka the KG83. then the KG11, and the Autodin 2 CRC32 designs in
I don't recall whether bisync, aka bsc used LRC8, 12, 16, or crc16 as
the error detection algorithm.
I don't think it used VRC. I did find a refresher that might help, but
I don't think the polynomial you have for crc 16 has enough terms.
BUT I could be misremembering.
On Sun, Jan 26, 2020 at 2:59 PM Mattis Lind via cctalk
<cctalk at classiccmp.org> wrote:
Hello IBM BSC Experts!
I am trying to figure out the CRC algorithm used by IBM BSC. I have tried a
lot of different settings in crcreveng but not getting a match.
I am pretty convinced that the CRC-16 used by IBM was
16 15 2
x + x + x + 1
This would give the polynomial 8005.
Anyone against this statement?
But what was the initial value?
I have two actual messages from equipment employing IBM BSC:
From this document (
I get that the CRC calculation is reset on SOH (01h) or STX (02h) and
accumulates until and including the ETX (03h). (excluding any SYN (32h)
I have tried crcreveng back and forth and I am not getting the CRC bytes
I think I have tried most things, different bit order, different initial
values. But nothing.
I also tried the mode in crcreveng where it searches for matches but it
always says "no models found". Maybe I am doing something wrong when using
Any clues? Surely there are someone out there that has been around for some
time and knows this, right?
On the topic of crc reveng I tried to verify how it works by using some
kind of known value: This article
has a specific example where a certain data in (75h) with initial value
90f1h gives output 6390h. I tried to get crc reveng to do the same, but
failed. There has to be some option I simply do not understand. I tried