Re: Obsolete documentation?

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On Mon, 17 Feb 2020, David Given wrote:

> On Mon, 17 Feb 2020 at 00:30, Paul Osmialowski <[email protected]> wrote:
>       I'm using null-modem cable I've made myself and been using it for y=
ears
>       (it corsses-over Rx/Tx and hardware control lines). It works nicely=
 with
>       Telix running under FreeDOS on my XT and minicom on 'big' Linux, at=
 speed
>       115200, which is the top speed for 8250 chip on the XT side.
>=20
>=20
> Exactly which 8250 is it? Some versions had major bugs which needed non-b=
ackwards-compatible workarounds in the BIOS. If the ELKS driver doesn't hav=
e these workarounds, which is likely if it's been targeted at later version=
s of the 8250 which didn't have the bugs,
> then it's likely not to work very well. I also believe (heard from Random=
 Person On The Internet) that driving an 8250 at high speed is difficult du=
e to the very small buffer, and you need very good interrupt performance, w=
hich I don't know if ELKS has.
>=20
> Information on the different 8250s is here:=A0https://www.freebsd.org/doc=
/en_US.ISO8859-1/articles/serial-uart/index.html
>=20
In this particular case (Amstrad PC 2086) it's on-board Amstrad 40049 UART =

(the same chip as used for a serial port in Amstrad Portable PC models), I =

don't know any more details, except that all DOS programs (e.g. Norton SI) =

report it as 8250. Yet at my old home I have Turbo XT with old, long 8-bit =

ISA I/O card having two regular 8250's on it and as far as I remember, it=20
was the first time I experienced losing bits while communicating ELKS and=20
Linux running on a bigger PC.
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