Path: utzoo!utdoe!generic!pnet91!taob
From: taob@pnet91.cts.com (Brian Tao)
Newsgroups: comp.sys.apple2
Subject: Re: DMA?
Message-ID: <620@generic.UUCP>
Date: 18 Apr 91 18:30:02 GMT
Sender: root@generic.UUCP
Organization: People-Net [pnet91], Etobicoke, ON
Lines: 29

From bazyar@ernie (Jawaid Bazyar):

>     The RAMfast cache is what is termed as "write-through", i.e. any
> data written to the card is immediately written through to the disk.

    That's what I thought, but I've noticed on some occasions the hard drive
activity LED would blink almost a full second AFTER the write operation.  This
only happens with small files (less than about 10 blocks).  On larger files,
the LED only blinks once every 1.5 seconds or so.  I might also add that I'm
using a Quantum P105S hard drive, which has its own 64K cache.  Still, 1.5
seconds to fill 64K?!?

>   What are you using to test your speeds in K/second?

    The Finder can pull in about 550K/second on a disk verify.  Prosel-16's
Volume Repair in Bad Block Lockout mode will read very close to 600K/second. 
The 150K/second figure was calculated by writing out a 2.2 meg sound file onto
a clean, optimized partition.

>    Someone needs to write a sort of "Nortonish" utility for the ][ series.
> That way we can compare ourselves at least to each other.

    How usable are the values from DiskTimer GS or Prosel-16's disk access
test?  I've been getting nice values (like 1.2 ms access for linear reads,
14.5 ms access for random reads) but I that doesn't say anything about the
transfer rate to/from the SCSI bus.

Brian T. Tao   *B-) |  t569taob@bluffs.scar.utoronto.ca  | "Though this be
U of Metro Toronto  |               - or -               |  madness, yet there
Scarberia, ON       |        taob@pnet91.cts.com         |  is method in 't."