more@ucf-cs.UUCP (duane more) (06/06/85)
Is anyone out there using the ibm pcnet (Sytek boards)
with DOS 3.1.
I work at Martin Marietta, and we have a balanced broadband
installation. One of the channels is being used for the
IBM-PCNET.
We have noticed some interesting characteristics of the PCNET.
One characteristic is that it has about a 25 percent
retransmission rate when you do copies from a server
machine to a user machine. This retransmission rate
is occuring in the absence of CRC errors, collisions,
alignment errors, or, buffer problems. We called IBM
and they say it is time delay to wait for an ACK/NAK.
This delay is not adjustable in the sense of setting
up the PCs for server/user relationships. IBM alleges
that they are going to send us a patch to alleviate
the problem.
This 25 percent is ONLY when you are doing large
file copies from a server machine to a user machine.
In the course of a 24 hour day, and, not trying
to hose up the net by doing these large server to
user copies, the retransmission rate is actually
about a MAX of 4 percent.
The Sytek board used with the PCNET generates a hell
of a lot of heat. (i.e. do not touch the board after it's
been on for 8 or so hours). I actually experienced hardware
faults and all sorts of squirrely errors after leaving my
PC on overnight. I Assumed that the board had gone bad
because the diagnostics had told me so, when in fact
it was the heat problem. After the board had cooled off
for a couple of days we reinstalled it to make sure it
was bad. Well, it worked after cooling.
There are a lot of very nice features about the PCNET
from a programmers viewpoint. They provide a slew of
interrupt calls for performing network type functions.
Interrupt 0x5c is provided to do most of the network
features (such as send,recieve,connect,listen, etc.).
Since the Sytek board uses the INTEL protocol chip,
there is a 0x5C interrupt for accessing the various
protocol statistics (Which is how we stumbled upon
the retransmission problem stated above).
I'd appreciate hearing via news or the netmail, ANYTHING
that anyone has to say regarding the PCNET.
Duane N. More
University of Central Florida
uucp: {decvax,akgua,duke}!usf-cs!more