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From: adamd@rhi.hi.is (Adam David)
Newsgroups: comp.sys.atari.st
Subject: Re: 1.44mb drives
Message-ID: <2914@krafla.rhi.hi.is>
Date: 16 Mar 91 04:29:40 GMT
References: <1991Feb28.085205.28239@phoenix.pub.uu.oz.au> <1991Mar06.123439.20676@actrix.gen.nz> <2886@krafla.rhi.hi.is> <2083@netmbx.UUCP>
Organization: University of Iceland
Lines: 30

In <2083@netmbx.UUCP> hase@netmbx.UUCP (Hartmut Semken) writes:

>adamd@rhi.hi.is (Adam David) writes:
>>It would be nice to change the step rate for the drives to suit the disk each
>>time a disk is changed.

>This cannot be done in a way, that will work on all versions of TOS,
>cause the location of the drive parameter block in RAM varies with the
>TOS version.

Surely there are sensible ways of finding where these are located, if this
is what's needed. Since it is possible to have separate steprates for drives
A: and B: then there must be a reliable method for changing the steprate on
individual drives. Install the routine into the mediach vector, it's almost
there now.

>>Does anyone know whether the WD1772 can handle 1024-byte sectors?

>This can be done in software. The WD1772 will read and write 256, 512
>and 1024 byte sectors. TOS will only work with 512 byte sectors.

Presumably the BIOS handles various sector sizes by using the BPB. Is TOS
really limited to using standard sectors? What about hard disks which also
have larger sectors? (or do they all use 512-byte sectors with more sectors
per cluster?). In the worst case a few routines will need to be patched or
rewritten if there are indeed incompatibilities. Besides cramming more data
onto the disks, being able to use 1024-byte sectors gives access to disks
written on other systems which use this format.
--
Adam David.  (adamd@rhi.hi.is)