[COFF] 52-pin D-Sub?
Arthur Krewat
krewat at kilonet.net
Sat Feb 29 02:35:04 AEST 2020
On 2/28/2020 9:11 AM, Clem Cole wrote:
>
> [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).
>
I ran a BBS for a few years back in the early 90's, and used a 486DX2-66
as my "front-end" to a Sun SPARC-IPC USENET setup. Using two V.34 and
one Worldblazer, running them at 38,400 baud, and taking advantage of
compression, it ran 100% download, 100% upload, or a combination across
three modems without even showing much load at all. It could have easily
taken more if I had the physical space (and the IRQs) on the ISA bus to
add more serial ports. Of course, the interrupt coalescing of the
16550's helped a lot. And I don't know what the saturation point was...
That was on x86 SVR4.2 (Consensys), using a shareware 16550 driver of
the time. The Worldblazer talked to a Trailblazer at Motorola for my
USENET feed and used G protocol, acceleration built into the Telebits.
8250's and 16540's were horrible. Much like DZ11's, eh? ;)
art k.
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