Serious flaws in

[Warren Tucker]

In article <1634 at boink.UUCP> harald at boink.UUCP (Harald Milne)
writes:
>Conclusion: SIO is broken, and broken bad enough to crash your system. 
>Don't use SIO with dumb serial cards.

Hmmmm....  I do asynchronous communications like most people
breathe...  pretty often.  I run two high speed modems (a Telebit
T2500 and a Microcomm 9624), an X-10 controller, another PC, an
AMTOR packet controller, a Wyse-60 terminal, an HF radio
controller, a 25MHz-1.2GHz receiver controller, a serial mouse
and a Ku-band VSAT, at speeds from 2400 to 38.4 and duty cycles
from 0 to 100%, all with dumb cards (Digiboard COM-8 and standard
COM1), 16450s and stock SIO.  I have a bit of trouble receiving
streaming 38.4 with the 450s during disk activity, but since I do
async protocol development, I derive a perverse sense of pleasure
at being able to generate errors merely by doing a find / :-).  I
have little or no problem with 9600 baud or below during any
system activity (my compressed news feed comes over the T2500 at
19.2 with 1400 ch/sec throughput, insignificant error rate).  I
plan to add 550s to some of the ports, but so far haven't really
felt hurt enough to bump it very high on the priority list.
Likewise, I have studied the wonderful FAS driver and keep
thinking over putting it in, but I don't need it except for
custom EIA signal diddling I'd like to get around to.

Of course, this is on a 20 MHz 386, but I had an 8MHz 286 for
three years and did abundant amounts of async at 9600 (maybe 3
billion characters/month) with 2.0.6, 2.1.1 and 2.3.1 XENIX 286,
with good luck.  I have had zero PANICs in six years of 24-hour
per day, 50% average utilization operation on a Compaq Deskpro
286/8 and 386/20.

The purpose of my verbosity isn't just to sound like Scotty on a
tour for the Admiralty, but to avoid you starting another
suburban legend.  I'm pretty fond of SCO's SIO, much more
tolerant and adaptive than any other I have seen.

Maybe I just hold my face right, but it -is- in a smile.

Smart serial cards are OK, but it's nice to be able to stick with
the straight and narrow: most smart cards don't use 8250
lookalikes.  I've programmed 8274s, 8530s, Z80 SIO, 6850 ACIAs,
68561 DUSCCs, and many others, even the wretched 68901.  The 8250 clan
ain't the best, ain't the worst, but there are more than a few in
use.  (Hint: Some enterprising soul should put a pair of
DUSCCs on an AT card.  Those devices do everything but laundry!)
 
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Warren Tucker                     emory!n4hgf!wht or wht at n4hgf.Mt-Park.GA.US
"I was 35 years old before I knew a pie was meant to be eaten." - Moe Howard