From mboxrd@z Thu Jan 1 00:00:00 1970 From: krewat at kilonet.net (Arthur Krewat) Date: Fri, 28 Feb 2020 11:35:04 -0500 Subject: [COFF] 52-pin D-Sub? In-Reply-To: References: <905CE999-5601-4521-847B-B2146C60B564@serissa.com> Message-ID: <6a44c9e7-1e7b-bd0e-df1c-6e2208e8b780@kilonet.net> 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: