19 Oct
2002
19 Oct
'02
2:49 p.m.
Patrick Finnegan wrote:
I would read the sector headers, which would give you
all that you
need.
Ok, I've looked over Intel's datasheet for the 82077A and 82078 that
they have online, and can't find any command that'll easily let me
just 'read sector headers'. Is there something I'm missing? The
closest command I could find was "READ ID HEADER" which would return
the first sector ID that it found. Do I need to read the entire track
or someting?
Fred Cisin wrote:
A: If you read a header, can you process the data, and
be ready to read
again in less than 1/50 of a second? Ifnot, then you could read even
numbered headers on one revolution, and odd numbered on another.
The READ ID HEADER command doesn't give you a choice as to what header
you're going to read; it just grabs the next one that comes around. So
if you want to know the exact sequence of headers on the track, you have
to be able to process them in real time.
You also don't inherently get any information on the positioning of the
IDs with regard to the index pulse. If you want that information, you
should do a read track, and then start reading IDs as soon as the read
track completes.
Since this seems to be a subject of interest to various people here, I
have decided to release dmklib even though it is not really ready for
prime time:
http://sf.net/projects/dmklib/
Here's the README:
dmklib README
$Id$
Copyright 2002 Eric Smith <eric(a)brouhaha.com>
dmklib is a library to read and write DMK format floppy disk images.
DMK format was developed by David Keil to represent floppy disk images
for use in TRS-80 simulators, and has since been adopted by other software
such as xtrs by Tim Mann and M.E.S.S. The specifications for the DMK image
file format are available on the web:
http://discover-net.net/~dmkeil/trs80/trstech.htm#Technical-DMK-disks
dmklib is supplied with several utility/demo programs for Linux:
rfloppy: read an actual floppy diskette and produce a DMK image
dmkformat: produce a blank formatted DMK image
dmk2raw: extract the data from a DMK image into a raw file
dumpids: read and display the sector IDs from an actual floppy diskette
dmklib and the utility/demo programs are in an *extremely* crude
state, however, they have been used successfully to read 8-inch single
and double sided, single and double density floppies. Although some
versions have been used in the past to read 5.25-inch floppies, it is
not known whether this release will do so. Since there has been quite
a bit of interest recently on the CCTalk mailing list in Linux
software to read floppy diskettes, I have decided to make this
prerelease available now rather than wait until I've cleaned
everything up.
Further development of dmklib will be hosted on SourceForge:
http://sf.net/projects/dmklib/
Eric Smith
19-Oct-2002
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation. Note that permission is
not granted to redistribute this program under the terms of any
other version of the General Public License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA