[COFF] 52-pin D-Sub?

[Adam Thornton]

A RocketPort multi-serial sounds really, really likely for an astrophysics
data collection instrument.  Thank you!  Mystery probably solved!

The 8250 was unbuffered or maybe had a 1 byte buffer, the 16450 had a
1-byte buffer, the 16550 had a 16-byte buffer.  I remember vividly how much
better my life got when I got 16550 serial ports for my '386.

Adam

On Fri, Feb 28, 2020 at 7:12 AM Clem Cole <clemc at ccc.com> wrote:

> Adam/Dave,
>
> For whatever's it's worth, in PC/AT ISA bus times, at least one of the
> serial port vendors (RocketPort was the vendor IIRC), used a DB-52P
> connector, that connected to an interesting 'tail' which had 8 DB25P
> connected to the DB25-S at the other end.   This allowed 6 data conductors
> (RCV/XMT/RTS/CTS/CD/DTR) * 8 ports, plus 6 grounds which again IIRC they
> interspersed among the remaining 6 ground pins.
>
> What I remember is that it was this specific board that was one of only a
> handful serial boards[1] that could run UNIX properly and hang Trailblazer
> modems off of it because they not only fully pinned, but they had
> single-chip custom USART with a good bit of buffering and hardware-based
> RTS/CTS flow control.  I think I may still have one somewhere, as I saw the
> cable for it when I was looking for something else over the Christmas
> holidays.
>
> [1] The original PC/AT used the NS8250 UART with no input buffering, which
> went through a couple of generations, eventually begat the *550 version and
> had I think an 8 character input buffer.  But IIRC none of them had
> hardware flow control.   I forget the # now, Moto made a nice dual UART
> with 16 chars of input buffering, that many of us on Unix workstation
> business used, but when we moved to BSD 386 and Linux, we were stuck with
> PC hardware, which had a particularly hard time with things like the
> Trailblazer  (which was the modem of choice for UUCP).
>
> Clem
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