Path: utzoo!attcan!uunet!bywater!acheron!archet!wlm
From: wlm@archet.UUCP (William L. Moran Jr.)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: 4-port card problem with 12/88 AOS
Message-ID: <66@archet.UUCP>
Date: 26 May 89 06:53:37 GMT
References: <39727@cmcl2.NYU.EDU> <39755@cmcl2.NYU.EDU>
Reply-To: wlm@archet.UUCP (William L. Moran Jr.)
Organization: A Desperate and Dedicated Crew
Lines: 41

In article <39755@cmcl2.NYU.EDU> edler@cmcl2.UUCP (Jan Edler) writes:
>Apparently this problem is known to IBM, and considered important,
>but there is no fix yet.  The problem also probably applies to psp
>ports (the ones on the motherboard of the 6150).  My guess, from looking
>at the code, is that you won't see the bug very often if you only use a
>single port of each type (asy or psp).

Yes, this problem is known to IBM (and has been for at least 18
months), A friend and I have done a great deal of experimentation to  
determine what causes (or exacerbates) the problem and have the found 
the following:

- Using even one serial port is sufficient to cause problems
- Fast disk controllers may make the problem worse
- The megapel makes the problem  worse, the APA16 is a little better,
  and the mono is a little better than that. Don't ever try to use the
  serial port with a megapel in glass tty mode - it's instant death.
- There is some threshold at which the problem really kicks in (i.e.
  at 2400 it is usually possible to ~t in tip 50k, but it is almost
  never possible to take 200k.
- A trigger level in the middle is better than the highest (I forget
  whether it's 14 or 15, and am too lazy to look in /usr/sys :)
- The problem is worse when using a modem than when using just a
  direct line (several unconvincing explanations for this have been
  offered).  

				Bill Moran

This is offered just as information. Nothing I say should be taken as
representing the views of IBM Research (I'm just a grad. student :)





-- 
arpa: moran-william@cs.yale.edu or wlm@ibm.com
uucp: uunet!bywater!acheron!archet!wlm or decvax!yale!moran-william
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