Author Topic: What is "saddle margin"?  (Read 893 times)

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Offline Alex EisenhutTopic starter

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What is "saddle margin"?
« on: July 22, 2023, 12:20:08 am »
Going through this datasheet
https://datasheet.datasheetarchive.com/originals/library/Datasheets-IS31/DSA00605584.pdf
I see this claim " has a recording system that puts top priority on saddle margin"
Which sounds great but what is "saddle margin"? I've never heard it and googling doesn't give much.
I suppose a "saddle" is the shape of some sort of response curve somewhere.
« Last Edit: July 22, 2023, 02:39:11 am by Alex Eisenhut »
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Online ejeffrey

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Re: What is "saddle margin"?
« Reply #1 on: July 22, 2023, 02:37:24 am »
I found this reference: https://en.m.wikipedia.org/wiki/Commodore_1571

Something about the worst case data pattern for transition density.
 
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Offline Psi

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Re: What is "saddle margin"?
« Reply #2 on: July 22, 2023, 02:45:42 am »
FYI The free ChatGPT version has no idea what saddle margin is.

It's good that it said it doesn't know, rather than making something up though.
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Offline Tomorokoshi

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Re: What is "saddle margin"?
« Reply #3 on: July 22, 2023, 03:17:10 am »
Perhaps it's a translation issue from Japanese to English, where either "saddle margin" was the original Japanese term or it somehow came out of the translation process to English.

The emphasis on filter characteristics may be related to the term.
 

Offline Alex EisenhutTopic starter

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Re: What is "saddle margin"?
« Reply #4 on: July 22, 2023, 03:33:35 am »
I found this reference: https://en.m.wikipedia.org/wiki/Commodore_1571

Something about the worst case data pattern for transition density.

Well that's interesting. I have 2 and half 1571s and I never looked that deeply into them. The "half" 1571 is the one built in to my 128D. They're very reliable drives IME so I never looked that deeply into them.

Sooooo I've been helping someone troubleshoot a SFD-1001 drive which packs 1MB on a DSDD disk, but these drives have trouble formatting the higher tracks where I guess the transitions are packed tighter.

My working hypothesis is that head wear changes the gap and therefore the frequency at higher tracks.  :-//

There is almost no information about floppy heads out there. So I've been searching for whatever ICs were used in floppy discs.
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Offline dmendesf

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Online amyk

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