Topics

370A floppy drive?


Joel
 

I posted this a little bit ago, but don't see it in the group. So here it is again -- Sorry if it's a repeat.


I picked up a nice 370A off of E-Bay. After fixing a few minor issues it works great. But I can't seem to make the floppy drive work. When I format a disk, it counts to the end and then fails. This happens on 720 and 1.4 floppies. If I try brand new, already formatted floppies, it says failed to write. So I figured the drive must be bad. But the drive is a bit strange. It has no power connector, just the ribbon cable. So obviously it's getting it's power over that. But I can't seem to find a replacement drive anywhere. I don't know if I can use a normal drive and run the power to a standard connector to the drive or if that drive is something special. Anyone have any expierence with the floppy on a 370A curve tracer?


Thanks,
Joe Loucka AG4QC


Ed Breya
 

The first thing to do is check to see if you've been trying with HD disks. If so, find some non-HD oldies to try out - you may be pleasantly surprised. If that doesn't work, you'll have to do some investigation and experimenting.

I would think the operator's manual should address the disk formatting info. I have had problems with old equipment with floppies because it couldn't format the more modern higher density ones, but it was OK if those same disks were formatted on a PC of the right vintage that could do it at different sizes on demand. These were from the evolutionary period when floppies were virtually the only removable storage, and they kept getting bigger. I have one old PC that's capable of doing this - the others for some reason don't give the choice to format in any size other than the defaults for the disk type. I don't know if it's due to the OS, the floppy drive unit, or some software or settings that are just right, but it has worked, so I have left it alone.

For the vintage of the 370, I would think the old single- or double-density 720/800 k size would be right to start with - it is a 3-1/2" not 5-1/4" right? I have tried to fake the drives into using the newer 1.44 MB "HD" types by modifying the indicators, but the magnetic material is different enough that it hardly ever worked. You have to get the oldies for 720/800 use - they are getting rare in circulation, although there should be plenty of NOS ones around out there, considering how many must have been made. I always save or scrounge old useless MAC and PC application programs just for the disks, to be formatted and reused for the old equipment. I don't bother with the HD types for this purpose.

Ed


Craig
 

Used one of these on a daily basis for many years. It will only work with a low density floppy.

You can use the 1.44 high density floppy but you have to put a piece of opaque tape over the hole to make the 370 think it is low density.

As I rmember, the floppy has to be formatted in the 370 for it to be recognized.

Craig
--------------------------------------------


Joel
 

Craig, Good information. Is there any chance I could buy a know good floppy from you that works in your 370? At least then I know for sure the drive is good.


Thank to everyone for your suggestions too. Got to love this stuff!..


Joe


 

A few things you might want to consider before using 1.44MB high density
floppies in a low density drive:

The higher density requires more tracks. More tracks requires that each
track be thinner. When you make the track thinner you have to increase the
amount of magnetic force to change the orientation of a domain bit of the
ferrite material coating the disk. So 1.44 MB floppies use stronger fields
in their write heads, and have greater positioning precision to track the
narrower tracks.

Problem arise when you mix HD floppies and LD floppies. The heads of LD
floppy drives are not strong enough to RELIABLY write data to an HD floppy.
When a HD formatted floppy is put into a LD drive the LD drive does not have
the precision necessary to follow the narrower track to read data RELIABLY.

The end result of these differences is that you may have problems with the
reliability of the data. It might be there one day and not be readable the
next day. Or one brand of floppies might work better than another. The
question you have to ask is can you trust your data will be retrievable when
you need it?

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Monday, September 08, 2014 8:05 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: 370A floppy drive?

Used one of these on a daily basis for many years. It will only work with a
low density floppy.

You can use the 1.44 high density floppy but you have to put a piece of
opaque tape over the hole to make the 370 think it is low density.

As I rmember, the floppy has to be formatted in the 370 for it to be
recognized.

Craig
--------------------------------------------














------------------------------------
Posted by: P Baker <craigyard99@...>
------------------------------------


------------------------------------

Yahoo Groups Links


Craig
 

Dennis,

Never found this to be a problem, because after placing the tape over the hole, the disk is formatted in the 370 drive at the larger tracksize.

First step is always format in the 370. After the 720K format there are no narrow tracks.

Craig


, 9/8/14, 'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes] <TekScopes@...> wrote:I

Subject: RE: [TekScopes] Re: 370A floppy drive?
To: TekScopes@...
Date: Monday, September 8, 2014, 5:12 PM


 









A few things you might want to consider before
using 1.44MB high density

floppies in a low density drive:



The higher density requires more tracks. More tracks
requires that each

track be thinner. When you make the track thinner you have
to increase the

amount of magnetic force to change the orientation of a
domain bit of the

ferrite material coating the disk. So 1.44 MB floppies use
stronger fields

in their write heads, and have greater positioning precision
to track the

narrower tracks.



Problem arise when you mix HD floppies and LD floppies. The
heads of LD

floppy drives are not strong enough to RELIABLY write data
to an HD floppy.

When a HD formatted floppy is put into a LD drive the LD
drive does not have

the precision necessary to follow the narrower track to read
data RELIABLY.



The end result of these differences is that you may have
problems with the

reliability of the data. It might be there one day and not
be readable the

next day. Or one brand of floppies might work better than
another. The

question you have to ask is can you trust your data will be
retrievable when

you need it?



Dennis Tillman W7PF

-----Original Message-----

From: TekScopes@...
[mailto:TekScopes@...]

Sent: Monday, September 08, 2014 8:05 AM

To: TekScopes@...

Subject: Re: [TekScopes] Re: 370A floppy drive?



Used one of these on a daily basis for many years. It will
only work with a

low density floppy.



You can use the 1.44 high density floppy but you have to put
a piece of

opaque tape over the hole to make the 370 think it is low
density.



As I rmember, the floppy has to be formatted in the 370 for
it to be

recognized.



Craig

--------------------------------------------



------------------------------------

Posted by: P Baker <craigyard99@...>

------------------------------------



------------------------------------



Yahoo Groups Links













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The magnetic material on the surface of a 1.44MB floppy requires a stronger field to change domain orientation so the write head of a 1.44MB drive generates a stronger magnetic field. In addition the track has to be narrower. That narrower track is harder for a 720K floppy to read RELIABILITY.

If you format enough diskettes you will eventually encounter issues if you mix LD and HD floppies with HD and LD drives.

The ultimate question you have to ask is do you trust valuable data to a floppy you may not be able to read in the future? If the data only needs to be accessible for a short time it won't matter.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: Monday, September 08, 2014 2:41 PM
To: TekScopes@...
Subject: RE: [TekScopes] Re: 370A floppy drive?

Dennis,

Never found this to be a problem, because after placing the tape over the hole, the disk is formatted in the 370 drive at the larger tracksize.

First step is always format in the 370. After the 720K format there are no narrow tracks.

Craig


, 9/8/14, 'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes] <TekScopes@...> wrote:I

Subject: RE: [TekScopes] Re: 370A floppy drive?
To: TekScopes@...
Date: Monday, September 8, 2014, 5:12 PM












A few things you might want to consider before using 1.44MB high density

floppies in a low density drive:



The higher density requires more tracks. More tracks requires that each

track be thinner. When you make the track thinner you have to increase the

amount of magnetic force to change the orientation of a domain bit of the

ferrite material coating the disk. So 1.44 MB floppies use stronger fields

in their write heads, and have greater positioning precision to track the

narrower tracks.



Problem arise when you mix HD floppies and LD floppies. The heads of LD

floppy drives are not strong enough to RELIABLY write data to an HD floppy.

When a HD formatted floppy is put into a LD drive the LD drive does not have

the precision necessary to follow the narrower track to read data RELIABLY.



The end result of these differences is that you may have problems with the

reliability of the data. It might be there one day and not be readable the

next day. Or one brand of floppies might work better than another. The

question you have to ask is can you trust your data will be retrievable when

you need it?



Dennis Tillman W7PF



-----Original Message-----

From: TekScopes@...
[mailto:TekScopes@...]

Sent: Monday, September 08, 2014 8:05 AM

To: TekScopes@...

Subject: Re: [TekScopes] Re: 370A floppy drive?



Used one of these on a daily basis for many years. It will only work with a

low density floppy.



You can use the 1.44 high density floppy but you have to put a piece of

opaque tape over the hole to make the 370 think it is low density.



As I rmember, the floppy has to be formatted in the 370 for it to be

recognized.



Craig

--------------------------------------------



------------------------------------

Posted by: P Baker <craigyard99@...>

------------------------------------



------------------------------------



Yahoo Groups Links













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Posted by: P Baker <craigyard99@...>
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Yahoo Groups Links


 

I have occasionally had this problem with some drives and some diskettes
although it may be difficult to distinguish from bad drives and bad media.

The issue is not the track size written by a 1.44M drive although that can be
problematical as well. The issue is that the coercivity of the 1.44M media is
higher so the 720K drive may have problems writing to it including producing a
narrow or partially written track.

Using a 1.2M diskette in a 360K drive almost always failed in my experience.

On Mon, 8 Sep 2014 14:40:40 -0700, you wrote:

Dennis,

Never found this to be a problem, because after placing the tape over the hole, the disk is formatted in the 370 drive at the larger tracksize.

First step is always format in the 370. After the 720K format there are no narrow tracks.

Craig


Craig
 

Dennis,.

I absolutely agree with you when discussing floppy disk interoperability between multiple types of systems, these are valid points you mention.

I apologize if I confused anyone. My comments were specific to the Tek 370 which in my experience will ONLY read and write low density disks formatted on the 370A. And if no low density disk is handy you can tape over the hole on a high density and it will format as low density at the larger track size (3.5 inch floppys are soft sector).

This was only mentioned as a practical solution for an immediate problem. I have used it hundreds of times and it works.

That being said, I would never use a floppy for long term storage, it is not a robust system. But it is the available method provided by Tek to transfer curve trace data from the 370A onto aother computer so it can be archived and included in reports. The floppy in the 370A was a great improvement that made this possible. It was fantastic when we could stop taking pictures of the CRT screen.

I close with a practical hint directly related to this discussion. I can not recomend in strong enough terms to never erase your important curves in the 370 memory until you have them safely transferred to your work computer. This will save you tons of griefe.

Craig




--------------------------------------------

On Mon, 9/8/14, 'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes] <TekScopes@...> wrote:

Subject: RE: [TekScopes] Re: 370A floppy drive?
To: TekScopes@...
Date: Monday, September 8, 2014, 5:49 PM


 









The magnetic material on the surface of a 1.44MB
floppy requires a stronger field to change domain
orientation so the write head of a 1.44MB drive generates a
stronger magnetic field. In addition the track has to be
narrower. That narrower track is harder for a 720K floppy to
read RELIABILITY.



If you format enough diskettes you will eventually encounter
issues if you mix LD and HD floppies with HD and LD drives.




The ultimate question you have to ask is do you trust
valuable data to a floppy you may not be able to read in the
future? If the data only needs to be accessible for a short
time it won't matter.



Dennis Tillman W7PF












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I think the most reliable floppy drives I used were the old single and double
density 5.25" drives. Data loss was much more common on earlier 8" drives,
5.25" high density drives, and 3.5" drives.

On Mon, 8 Sep 2014 16:32:51 -0700, you wrote:

That being said, I would never use a floppy for long term storage, it is not a robust system. But it is the available method provided by Tek to transfer curve trace data from the 370A onto aother computer so it can be archived and included in reports. The floppy in the 370A was a great improvement that made this possible. It was fantastic when we could stop taking pictures of the CRT screen.


Mike Malone
 

May I add some of the useless information I have gathered over the years?

In the 5.25" floppy format there were two main types - the 5.25" double density (DD) and the 5.25" high density (HD).
The 5.25" SD disk had 40 tracks and a capacity of 360kB whereas the 5.25" HD had 80 tracks and a capacity of 1.2MB.
There were two main types of 3.5" disk too - the 3.5" 720kB capacity DD and the 1.44MB HD. Both had 80 tracks at 135 tracks per inch. The increase in capacity was achieved by increasing the number of sectors per track from 9 to 18 (and therefore doubling the capacity per track).
There was a small, but significant, increase in the magnetic flux density of the media and with the capabilities of the read/write head to accommodate this media.
The 3.5" HD disk drive was backwards compatible with the 3.5" DD disk drive.
The 3.5" DD disk drive was not forwards compatible with the 3.5" HD drive.
Likewise with the 5.25" units.
That doesn't mean that it would not be possible for a 3.5" DD drive to be able to read a 3.5" HD disk formatted with 9 sectors/track (ie as DD) or be able to write (format and.or write data) to such a disk, although the latter would be more difficult than the former.

The biggest causes of the interoperability of disks between different disk drives is (was) the relative alignments of the read/write heads and the timing of the track 'index' pulse.
The position (and skew) of the head that reads the disk must be closely aligned with that of the drive that wrote it. Likewise there is an index pulse that is used to indicate the start of each track. Should this pulse not be within spec then the track cannot be found by the system that is trying to read the disk even if the track alignment is perfect and the data on the track is perfectly readable. (The does not apply to MAC DD disks - the MAC wrote tracks with wanton abandon).
However for a situation where the only drive that will read the disk is the one that will have written to it then this situation does not arise.

Damage to the media surface from environmental debris (dust and dirt particles causing scratches on the media surface) was an ever-present risk, often rendering a particular sector, or a bunch of sectors on adjacent tracks, unreadable. (Each sector had a crc).


Oh, and dirt and debris can build up on the innards of the drive as pc fans usually pulled dirt in through the front opening. This would build up on the shaft of the head positioning mechanism (being greased) in particular. The read/write heads also accumulate a coating from the media and require occasional cleaning.

Anyway, just my remembrances, make of them what you will.

Mike


bobvines00
 

Joe,

You may be able to buy the low density 3.5-inch diskettes from
http://www.floppydisk.com/index.htm. I have purchased "old" diskettes
from them in the past.


Bob


Dale H. Cook
 

At 08:56 AM 9/9/2014, Mike Malone wrote:

In the 5.25" floppy format there were two main types - the 5.25" double density (DD) and the 5.25" high density (HD).
One historical note - before the DD floppies there were 180 kB single sided single-density 5.25" floppies, used in the Osborne 1. After the 360 kB floppies were introduced Osborne offered an upgrade to those drives, but my Osborne 1 still has the original 180 kB drives.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html


Mike Malone
 

Were they the ones with a single head and where to write to the 'other' side of the disk the disk had to be removed from the drive, flipped, and reinserted?
Cool!


David Holland
 

"flippy" floppies.... I used them quite a bit with my Apple II. (A
whole 140K, per side w/ DOS 3.3)

They had to have a write protect notch cut in the other side,
otherwise, the drive thought the back was write protected once you
flipped it.

On Tue, Sep 9, 2014 at 3:27 PM, Mike Malone mikea_a_malone@...
[TekScopes] <TekScopes@...> wrote:
Were they the ones with a single head and where to write to the 'other' side of the disk the disk had to be removed from the drive, flipped, and reinserted?
Cool!





------------------------------------
Posted by: Mike Malone <mikea_a_malone@...>
------------------------------------


------------------------------------

Yahoo Groups Links



Dale H. Cook
 

At 03:27 PM 9/9/2014, Mike Malone wrote:

Were they the ones with a single head and where to write to the 'other' side of the disk the disk had to be removed from the drive, flipped, and reinserted?
You nailed it. All of the 180 kB floppies were coated on both sides, but supposedly tested good on only one side. That didn't stop people from cutting a write notch on the other edge and flipping them. IIRC some computers (Early TRS-80?) used the opposite side from what the early CP/M machines used. Many users of 180 kB drives bought 360 kB floppies and notched and flipped those. I just used 360 kB floppies in single-sided mode since they were cheap enough.

I still have the Osborne 1 stored here, as well as a Kaypro 4-84 and a Kaypro 1. The last time that I pressed a CP/M machine into service was more than 20 years ago. I used it to control a speech synthesizer - my boss had bought his fifth radio station and we were stunting before a format change. I have lots of Osborne, Kaypro, and CP/M-80 reference works boxed up and stored, and beaucoups CP/M-80 software archived on CD including a program that reads and writes CP/M-80 floppies with an MS-DOS 5.25" 360 kB drive. The only reference works from my CP/M days that are out and shelved are some processor references (8080, 8085, and Z-80) that I occasionally need when working on a dedicated microprocessor system.

Speaking of floppies, you aren't a floppy fogie unless you have worked with 8" floppies. I had those in an IBM System/34 decades ago.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html


Brad Thompson <brad.thompson@...>
 

On 9/9/2014 4:03 PM, 'Dale H. Cook' bridgewaterma@... [TekScopes] wrote:

At 03:27 PM 9/9/2014, Mike Malone wrote:

Were they the ones with a single head and where to write to the
'other' side of the disk the disk had to be removed from the drive, flipped, and reinserted?

You nailed it. All of the 180 kB floppies were coated on both sides<snip>

Speaking of floppies, you aren't a floppy fogie unless you have worked
with 8" floppies. I had those in an IBM System/34 decades ago.

Hello, Dale and the group--

Does anyone remember the Tabor 3 1/4-inch floppy drive? IIRC, the media were soft-sided
discs more akin to a 5 1/4-inch floppy than the hard-shelled Sony 3 1/2-inch discs.

The Tabor drive used a miniature power connector with the same form factor and contact spacing as
the Sony drive, but the Tabor drive's power pins were reversed. As you can imagine, this
led to a few smoked drives, both Sony and Tabor<g>. (We were evaluating these
as a step up from DEC TU-58 tape drives.) IIRC, Tabor was based in Westford, MA.)

Also IIRC, Sony's early 3 1/2-inch drives came in several versions, one of which wound
up in Apple's earliest Macs.

73--

Brad AA1IP

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com


 

Woohoo! I still have my CP/M 8" floppies. What do I win?

On Tue, 09 Sep 2014 16:03:58 -0400, you wrote:

...

Speaking of floppies, you aren't a floppy fogie unless you have worked with 8" floppies. I had those in an IBM System/34 decades ago.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html


Richard R. Pope
 

Brad and Dale,
I never used any 8" floppies but I did see them. There was a company in Palo Alto that had them in stock. I used a lot of 5.25 floppies. I started with a 1540 drive for my C= VIC. I was smoking compared to the dataset. The thing is is that I still have some of the tapes from back then.
Then I bought a C-64, C-128, and finally an Amiga 1000 with a 3.5" drive. That was great. It was two years before a hard drive interface became available. My first HD was 30MB. Now I was in heaven. Ah Yes! Those where the days. I still have an IBM 1GB SCSI drive from my Amiga.
Thanks,
rich!

On 9/9/2014 4:10 PM, Brad Thompson brad.thompson@... [TekScopes] wrote:
On 9/9/2014 4:03 PM, 'Dale H. Cook' bridgewaterma@...
[TekScopes] wrote:
At 03:27 PM 9/9/2014, Mike Malone wrote:

Were they the ones with a single head and where to write to the
'other' side of the disk the disk had to be removed from the drive,
flipped, and reinserted?

You nailed it. All of the 180 kB floppies were coated on both sides<snip>
>Speaking of floppies, you aren't a floppy fogie unless you have worked
with 8" floppies. I had those in an IBM System/34 decades ago.

Hello, Dale and the group--

Does anyone remember the Tabor 3 1/4-inch floppy drive? IIRC, the media
were soft-sided
discs more akin to a 5 1/4-inch floppy than the hard-shelled Sony 3
1/2-inch discs.

The Tabor drive used a miniature power connector with the same form
factor and contact spacing as
the Sony drive, but the Tabor drive's power pins were reversed. As you
can imagine, this
led to a few smoked drives, both Sony and Tabor<g>. (We were evaluating
these
as a step up from DEC TU-58 tape drives.) IIRC, Tabor was based in
Westford, MA.)

Also IIRC, Sony's early 3 1/2-inch drives came in several versions, one
of which wound
up in Apple's earliest Macs.

73--

Brad AA1IP


Bert Haskins
 

On 9/9/2014 5:48 PM, David @DWH [TekScopes] wrote:

Woohoo! I still have my CP/M 8" floppies. What do I win?
Would you like a pair of drives for them?
Just goes to prove that no matter how bad a "string saver" you are,
there's always someone worse.
As of last march, I can finally get rid of them.
Now if I can just reach that top shelf......


To address the narrow/wide track problem.
You can try moving the floppy close to the core laminations of a powered
power transformer and then reformat the floppy.
Hold the disk close and then move it away.


On Tue, 09 Sep 2014 16:03:58 -0400, you wrote:

...

Speaking of floppies, you aren't a floppy fogie unless you have
worked with 8" floppies. I had those in an IBM System/34 decades ago.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html