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From: athornton at gmail.com (Adam Thornton)
Subject: [COFF] 52-pin D-Sub?
Date: Fri, 28 Feb 2020 07:34:50 -0700	[thread overview]
Message-ID: <CAP2nic0nX5AM6d27xgEOqu55QKVmr5wpC5+mCyW9p8L=vKYCiA@mail.gmail.com> (raw)
In-Reply-To: <CAC20D2Or=9DnR287GottTO=1hnZyH4F6TLyipHhkqtepquKVdQ@mail.gmail.com>

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
> _______________________________________________
> COFF mailing list
> COFF at minnie.tuhs.org
> https://minnie.tuhs.org/cgi-bin/mailman/listinfo/coff
>
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  reply	other threads:[~2020-02-28 14:34 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-27 23:37 athornton
2020-02-28  0:04 ` dave
2020-02-28  1:37   ` stewart
2020-02-28  2:12     ` athornton
2020-02-28  4:12     ` dave
2020-02-28  4:18       ` dave
2020-02-28 14:11         ` clemc
2020-02-28 14:34           ` athornton [this message]
2020-02-28 21:23             ` dave
2020-02-28 16:35           ` krewat
2020-02-28 21:28             ` dave
2020-02-28 21:44               ` clemc
2020-02-28 21:58                 ` dave
2020-02-28 22:20                   ` clemc
2020-02-28 23:22                     ` pechter
2020-02-29 13:12                       ` emu
2020-02-29 15:45                         ` krewat
2020-02-29 15:49                           ` clemc
2020-02-28 22:38                   ` pechter
2020-02-28 22:05                 ` drb
2020-02-28 22:28                   ` clemc
2020-02-28 22:26                 ` pechter
2020-02-28 22:36                   ` clemc
2020-02-28 23:40                     ` pechter
2020-02-29 16:52                       ` clemc
2020-02-28 23:54                     ` pechter
2020-02-29  9:59 rudi.j.blom

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