Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!van-bc!ubc-cs!alberta!ccu!umcarls9
From: umcarls9@ccu.umanitoba.ca (Charles Carlson)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Problem: modem errors w/ disk cacheing?
Message-ID: <1990Mar10.005746.4047@ccu.umanitoba.ca>
Date: 10 Mar 90 00:57:46 GMT
References: <5190079@hplsla.HP.COM> <2395@unocss..unl.edu>
Organization: University of Manitoba, Winnipeg, Canada
Lines: 29

In article <2395@unocss..unl.edu> ho@fergvax.unl.edu writes:
>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.
>

In the DSZ documentation, CF also recommends changing your uart chip
to a NS16550AN instead of an 8250 or 16450.  The NS16550AN has a 16 deep
receiving buffer<I assume that means 16 bytes> for machines faster than
4.77Mhz and receiving at speeds greater than 9600 bps.

Charles