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From: terry@eecea.eece.ksu.edu (Terry Hull)
Newsgroups: comp.unix.questions,comp.sys.ibm.pc
Subject: Re: 100ns .vs. 120ns
Summary: Don't do it.
Message-ID: <519@eecea.eece.ksu.edu>
Date: 6 Jan 89 14:54:22 GMT
References: <377@fantasci.UUCP>
Reply-To: terry@eecea.eece.ksu.edu (Terry Hull)
Distribution: na
Organization: Kansas State University, Manhattan
Lines: 34

In article <377@fantasci.UUCP> jep@fantasci.UUCP (Joseph E Poplawski) writes:
>How bad of a speed difference would my UNIX V.3 for the 80386 system incur if
>I added 120ns chips instead of the 100ns chips it already has 2 meg of?  The
>system is a personal system with no more than 3-5 users on at the
>extreme most.

First, system load does not have much to do with memory speed
requirements.  The processor runs full speed all the time whether it
is waiting for keyboard input or moving a 1MB array in memmory.  

Memory is not a good place to economize when you are using UNIX.  For
some reason, UNIX tends to bring out memory errors in a system faster
than other OSs like MSDOS.  You do not mention what machine you have,
but in general:

  16 MHZ  100ns
  20       80ns
  25       60ns

I got lucky when I purchased my Inboard/386 AT, it is a 16MHZ 386, but
it uses a 64K static cache and will run with 120ns chips.  

Remember, if the machine would run reliably with the slower chips, the
manufacturer would have used them to save money.  This might not be true if
a manufacturer got a particularly good deal on faster chips though.  

You will know if it is not working when your machine dies with panic
messages.  

-- 
Terry Hull                    Department of Electrical and Computer Engineering
                                           Kansas State University
INTERNET: terry@eecea.eece.ksu.edu          Manhattan, KS  66502 
UUCP: rutgers!ksuvax1!eecea!terry