In sci.electronics.equipment Chris Campbell wrote:
I really don't want to go with a PC-based solution, as I've been down
that road and I know where it ends

At one job, we had an ancient HP serial analyzer and a PC-based one
on a laptop. The laptop one didn't work at first, and the HP, despite
being ~25 years old at the time, worked fine. I finally futzed with
drivers and reinstalls on the laptop for about half a day and got it
working well, because I needed to go faster than the 9600 bps the HP
could do. So I understand what you're saying.

I don't remember the model of that analyzer, but it was from the mid
70s or so. It had a CRT and about a 20-key keypad on the front, not
a keyboard. Above the screen, there was a matrix of holes that you
would plug gold-plated pins into to set which lines it was monitoring,
how the modem control lines worked, etc.

At another job, I used an HP analyzer that was newer - it could store
data on a 3.5" 720K? floppy. Pictures from Google (below) tell me
that this analyzer was probably newer than a 4951, while the one I
talked about above was older.

Is an HP4951 going to do this for me?

I don't know if you found this already, but
http://www.classiccmp.org/pipermail/...er/002207.html
has a link to a scanned HP ad at
http://www.helmut-singer.de/pdf/hp49...955a-4972a.pdf ,
which says the 4951C does 232C and 422A. No mention of 485. Googling
on "hp 4951a" and "hp 4951b" also produces useful results, with
specifications and a few mentions of units for sale.

Matt Roberds