Using 3.5" HD drives on CP/M systems

From: Herb Johnson <>
Date: Sat Feb 5 10:07:15 2005

Randy McLaughlin wrote:

> From: "Herb Johnson"
>>"Randy McLaughlin" writes [in exerpts,, my text in brackets]:
> <snip>
>>I think Randy is looking for a CONSENSUS, not a "quorum", but in any
>>event he is looking for an acceptable standard. He did not get a lot of
>>responses because 1) it's only been a few days, and 2) it's a
>>technically tough subject, and 3) it's an OLD subject over the years.
> In fact I am hoping to put togather a quorum, I want a select group of
> technically minded people to come together and have their own opinions and
> ideas. CP/M on 3.5" drives exist. 3.5" HD media has technical issues that
> are unique to it. If we can get a quorum then a consensus can be formed.

My point was that you did not wait very long - a few days - for comments
or responses. Whether you want a quorum, consensus, or "a select group",
it will take time.

I also commented on the limits of single density, FM, controllers.

> I agree that finding a PC that can handle FM is basically impossible for a
> new off the shelf system, which is why I keep an old PC that does handle FM.
> In this case it does not matter what drive and media is used...

You mentioned HD media, the thread subject is "HD drives", so I thought
that was your proposed "standard". But it is more likely that 3.5" DD
media and drive settings will work for FM/single density/8-inch systems,
than HD.

> ..... if all you have
> is FM then 3.5" FM is accepatble While you won't be able to use it on most
> PC's that applies for any FM disk (3.5", 5.25", or 8"). Note I am not
> recomending anyone stop using 8" I just am recomending standardizing how we
> use 3.5" when we do use it.

Two comments on 8-inch disks and CP/M. 1) there already IS an 8-inch SSSD
standard. Has been for a long time. single sided, 26 sectors, two boot
tracks, etc. 2) Your discussion was in parallel with, if not encouraged
by, another comp.os.cpm thread about replacing 8-inch drives with 3.5"

If you want more discussion and a "select group", I suggested two very
qualified people. Of course it is up to them to show their interest and
to enter into your discussion. But as I commented, and PLEASE READ THIS

>>One personal note. This took a few hours to write. It takes time to make
>>a good, technical "argument". It took time for me to complile all the
>>info on my site, and time for THOSE people who wrote it to do their
>>work. It does not take long to propose a popular idea, and it's fun;
>>it's less popular (and more work) to say "here's why it may not happen".

My point? Randy will have to wait for more than a few days to build
whatever "consensus" or "quorum" or "select group" will construct his
standards. And, a standard, or now standardS PLURAL (FM and MFM) will
take some time and technical care to construct and VERIFY. Already, it's
clear there would have to be at least two standards: one for
single-density/FM only systems, one for double density. Oh, those older
systems may need a single sided standard too...

> I appreciate your comments, I agree that no standard is in [sight] and may
> never be agreed upon by enough people. I also agree we need Amardeep and
> others to pipe in.
> I expect a large base to fight using 3.5" media but I find that 3.5" media
> is so much easier to deal with on a variety of levels.

"Easy" does not make it possible. And explaining the technical limits is
not "fighting". But there are other reasons not to put 3.5" drives on
the oldest systems. One "reason" is more of a preference: to run systems
with all original hardware, including the original 8-inch disks. Another
reason, which I mentioned previously, is to make sure that your system's
disks can be read and written by ANOTHER IDENTICAL system of the same
brand and model. (You may get an offer of software from another owner of
your brand & model of system; too bad you can't read their disks...)

I think the problems of a set of "standards" for using 3.5" drives and
media fall into two categories. First, the technical limits of the
oldest systems. Already it appears that single density will need its own
standard - that's one example of technical limits. Reliability is a
technical issue also: if you use odd formats at odd data rates, you may
not get reliable results. Like, using HD disks at DD formats: it may
work, sort of. Second, the general issue of cross compatibility. When
you use new disks on old systems, you'll have "funny" formats that will
be very unique, to the point that NOBODY BUT YOU can read your disks.
Backups that can be read by only one computer are not backups, when that
computer dies.

Sorry I don't have time to contribute further to this discussion. My Web
pages and my comments above will have to do. At least I helped establish
that single density has unique challenges.

Herb Johnson

Herbert R. Johnson, voice 609-771-1503, New Jersey USA
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Received on Sat Feb 05 2005 - 10:07:15 GMT

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