Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!ssbell!mcmi!unocss!ho@fergvax.unl.edu
From: ho@fergvax.unl.edu (Tiny Bubbles...)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Problem: modem errors w/ disk cacheing?
Message-ID: <2395@unocss..unl.edu>
Date: 6 Mar 90 00:36:52 GMT
References: <5190079@hplsla.HP.COM>
Sender: root@unocss..unl.edu
Reply-To: ho@fergvax.unl.edu
Lines: 31

From article <5190079@hplsla.HP.COM>, by kens@hplsla.HP.COM (Ken Snyder):
>> From hamilton@cell.mot.COM Thu Mar  1 07:59:40 1990
>> 
>> When transferring files at high rates (9600, 14400), I encounter
>> frequent errors (like every other block) using ymodem or xmodem.
>> 
>> A friend told me that the disk cacheing is to blame because interrupts
>> are disabled while the cacheing is being executed and at high bit rates
>> 
>> Can anyone confirm that this is true?  If it is true, is there any way
> 
>    Yes this is true.  There are a couple of ways to get around it.  I'm

Someone shove a sock in my mouth if I'm wrong, but Chuck Forsberg says in his
ZCOMM documentation that this problem is caused not by the disk cache per
se, but by using a cache to exTENded memory.

It seems that using extended memory requires going to protected mode, and
coming back requires a hard reset of the computer.  It is during this hard
reset that interrupts are lost.

Supposedly, exPANded memory (true expanded memory -- not utilities that map
extended to expanded, but actual LIM memory on a hardware card) does not
have this problem.  I have an XT, so obviously I don't know anything about
extended memory's performance.  I do occasionally run a disk cache (the one
which comes with PC Tools) with no ill effects.

---
        ... Michael Ho, University of Nebraska
Internet: ho@hoss.unl.edu               USnail:  115 Nebraska Union
                                                 Lincoln, NE 68588-0461