From: bv@wjv.com
In article <11qm9svgnpg5c01@corp.supernews.com>, James wrote:
>
>
>Bill Vermillion wrote:
>> In article <437781BF.C9E7A099@catholicexchange.com>,
>> Stephen Bendzick wrote:
>>
>>>Homer J Simpson wrote:
>>>
>>>>"Bill Vermillion" wrote in message news:Ipuz3M.onD@wjv.com...
>>>>
>>>>
>>>>>Frank - am I losing what little mind I have left.
>>>>>
>>>>>Naturally Laserdisk, CDs and DVD start at the inside - and this is
>>>>>why you can use different sized disk.
>>
>>
>>>>>I was almost sure that floppies and hard drives use track 0 as the
>>>>>outermost track.
>>
>>
>>>>It's not so much the disks or the drives but the FD controller
>>>>chips that were hard coded this way. I suppose you could invert
>>>>signals but that would screw up the compensation that kicks in
>>>>part way through the tracks. I've never seen a floppy or hard
>>>>drive that worked differently but I don't know much about the
>>>>newest hard drives.
>>
>>
>>>Well, there's nothing to /prevent/ you from designing an FDC chip
>>>that numbers the tracks from 0 starting at the innermost track
>>>and uses standard floppy drives. However, there is something
>>>intrinsic to the design of standard floppy drives that strongly
>>>biases them toward starting from the outside--the only indication
>>>of head position that most floppy drives give is a binary signal
>>>indicating whether the head is at the outermost track; the FDC
>>>must keep track of head position by first stepping out to the
>>>outermost track, to get a known head position, and then counting
>>>steps from there.
>>
>>
>> That brought back memories. I'd have to have my floppies aligned
>> every few months and until I put DS/DD thinline TEAC's on the
>> system I could get about 1 year out of the drives. It was
>> a 24x7 BBS - and the model I ran for over 33000 consecutive
>> power-on hours - except when Florida Flash and Flicker - the
>> nickname for the local power company - would interupt things.
>>
>> But if you pushed and Apple II hard you'd wear out the drives.
>>
>> Apple had no concept of where the head was, so to ensure it
>> was at track 0 it would step back 40 times. If you were at track
>> 1, you banged the head against the stop 39 times - which was not
>> the best design. But then the two Steve's always went with their
>> own ideas on design - usually finding the cheapest way to do
>> something - and made the incompatible with the industry.
>>
>> And as I typed this I had another flashback.
>>
>> Atari used to have copy protection on their disks so they could not
>> be duplicated. No problem. Stick them in a model I and do a
>> track by track copy. Tandy used standard parts - which made life
>> easier.
>>
>> I modified the format program on the model I so that instead of
>> writing E5 on the track it wrote BILL VERMILLION on a
>> format.
>>
>> Since many people just made direct copies, if someone copied
>> something that I had originally formatted you could find traces of
>> that on the copy.
>> Those were fun days.
>> Bill
>Well now this is a mixed bag for me. I am finally reaching a point
>where I can take my old Mdl I & Mdl III/IV's out of mothballs and I may
>be facing media problems. About 1,200 5 1/4's and several hundred 3
>1/2's. Darn. I'm going to have to check into that media bit. BTW the
>track zero sensor was also able to be moved out for an extra 2-6
>tacks/cylinders for most manufacturers to get a bit more capacity. Of
>course that made them, the disks, unreadable by other machines. Old
>form of copy protection against highjacked media. I wrote a small basic
>program to control the WD controller and place the head where track 0
>was supposed to be then poked the correct data into memory so
>conventional disks could be read by these unconventional drives. I also
>had 3 1/2's running in the boxes almost as soon as they became
>available. For replacement 5 1/4's if you can find any of the old
>Mitsubishi drives they were excellent at the time.
Oh I don't need any replacement 5.25" drives. I still have 2 or 3
from my original model I. But when I used it as a BBS I upgraded
to DSDD drives - 80 track - and got about 720K. I have at least
two of those - TEAC - that were operable when I put them in
storage.
I'm a genuine pack rat. I still have a pair of 8" SSDD drives
that I put in big external cases when I diddled with CP/M. And I
have a Tandy external drive bay with 2 slim line drives in it.
Drives I'm not short of - time I am short of.
>Also for the 40 track single sided drives the old Wangco could
>not be beat. Mitsubishi was a band drive with a flat on the motor
>shaft so the position would remain solid and the Wangco was a
>screw drive also with a flat.
And I have a 'collectors' item. In name only not worth that much.
It's high upon a shelf behind me with at least two computers on the
table in front so I can get the exact details.
But it's a Shugart SA-400 ?? - original 35-track drive. And by
original I mean ORIGINAL. The circuit board is held in place
by phosphor-bronze ?? springs. And the head positioner is a
composite wheel on the back that has a track for the head
positition to sit.
The serial number is hand-written - in the 1600 range. It was
an evaluation drive from the first prototype run of 5.25" drives
made. It's a good conversation piece. :-)
>As old as it was the Wangco could step with less than 6
>millisecond pulses reliably. I will post again when I have a
>chance to check out some of the media. I also have some original
>TRSDos 6/LDOS OS sets as originally shipped if anyone has an
>interest. Haven't checked the market for any of my old Tandy
>stuff for several years but the time will come.
I have those too - going back to the 3.x and 4.x VTOS that preceded
LDOS. And I have the original LDOS for the Max80 - but I need to
get around to putting diodes in the power supply to get one of
those backup running if possible.
At heart I think I'm a junk collector :-) 6000 square feet of junk
in a 1500 square foot house!
Bill
--
Bill Vermillion - bv @ wjv . com
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* Origin: you cannot sedate... all the things you hate (1:229/2)
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