Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mit-eddie!ll-xn!ames!pasteur!ucbvax!cogsci.berkeley.edu!palmer
From: palmer@cogsci.berkeley.edu (Stephen E. Palmer)
Newsgroups: comp.sys.ibm.pc
Subject: hard disk performance for IBM-ATs
Message-ID: <23776@ucbvax.BERKELEY.EDU>
Date: 26 Apr 88 20:43:54 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: palmer@cogsci.berkeley.edu (Stephen E. Palmer)
Distribution: na
Organization: University of California, Berkeley
Lines: 16

I am looking for some information about speed of data transfer from hard
disks for an IBM-AT (8 MHz, 4 MB memory).  I am using the AT to control
real-time experiments on human vision using an AT&T TARGA-24 graphics board. A
full 512 X 512 TARGA image takes about a megabyte of storage, and so speed
of transferring them to the graphics board is essential for our experiments. 
I currently am using two standard IBM 30-MB drives.  I don't know the specs on
them, but the question is whether I could decrease the time required to get
stored images onto the TARGA by purchasing a higher-speed, higher-performance
disk for use on this machine.  I am not even sure where the bottleneck is: the
access time of the disk, the data transfer rate of the disk, the speed of the
disk controller, or the speed of the CPU.  I do know that the images take much
less time to display when they are stored on RAM disk than when they are
stored on the hard disk, so the currently limiting factor is unlikely to be
the CPU or the rate at which the TARGA can accept data. 

Steve Palmer (palmer@cogsci.berkeley.edu)