Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: SACC-guy on April 30, 2015, 06:04:50 AM
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Okay, from the 1000 on (not high density drive).
We always say its 880k!
Is this the gross amount, if so what do they format to 8??k...
(http://www.amigahistory.co.uk/floppy1.html)
Older machines, such as the A1000 & A500 have a storage limit of 837k. Although these machines can read 880k disks with a device handler (a small file that allows the Amiga to understand the disk), they cannot boot from them when you switch on your computer.
Is this true?
Thanks,
M
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Huh?
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OFS vs FFS?
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I think it refers to formatted capacity using the Original File System (OFS) or the Fast File System (FFS). Before Kickstart 2.0 you could only use OFS on floppies.
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http://en.wikipedia.org/wiki/Amiga_Old_File_System
http://en.wikipedia.org/wiki/Amiga_Fast_File_System
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The standard DD floppy can store 1 MB of data. This is the total amount of bits that can reside on the disk if you were to just run numbers out to it; then you could read 1 MB back as one (1) big hunk of data. Then again, you half step the head and lay data in between a full head step -- this is not stable, but data lays here as a residual of the full tracks laid down -- a way for a freshly formatted disk to have it's prior content discovered; useful for the 3 letter anal orifice types like the TSA, FBI, NSA, and your MOM. But let us say we wanted to put files on the disks, then we need to store the names of the files, where they were stored by track, sector, byte, etc. So in addition to the names, we now needs a map of the disk or BAM, that tells where each file has its data. Now what if data was written to shi(tt)y flimsy less that a piece of paper thickness magnetic media; well we might want to store some information to tell us our data is messed up or not, so we need something as simple as a CRC (cyclic redundancy check) that is the same when written as when read. Well, most of can see that now we have lost a chunk of change from that 1 MB of space. If we are really anal retentive, the we end up like IBM with 720 KB of space, or we do acid like Steve Jobs and squeak 80 KB more from our Orange Sunshine and get not only a disk that changes speed to keep the same data flowing on the little circles in the middle, as the large suckers at the outside of the disk, or 800 KB. But instead we are the Amiga run by cools dudes who make up a file system similar to TripOS and call it the Original File System -- we start with a disk layout that with all that great fun stuff above and with some added nonsense that made sense when Mitchy and Joe Pillow were up all night dancing. But a wee bit later, we grab some amphetamines and realize, "Dude, this is slow and stupid!" We then think up a better file system and bypass Smarter for Faster; we get better performance, weed out some of the stupid crap, add International modes and Directory caches, and, "Bob's you Uncle!"
Any help?
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And even diskspare.device:
"It is a completion or replacement of the trackdisk.device,
which lets you format your disks with 960 kB or 984 kB"
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"It is a completion or replacement of the trackdisk.device,
which lets you format your disks with 960 kB or 984 kB"
Man, those few extra kilobytes were way important back in the day! :roflmao:
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How good is the error correction and subfolder (directory within directory) support? Is it supported by DiskSalv? How does the speed of access to a file compare to FFS? Can it be used on other devices, like Catweasel? Does it ramp up to HD floppies? Or is it a pebble on the superhighway of computing, best left squished between the treads of a tire belonging to a Dodge 1968 Super Bee heading for that curve in the road that it will never make?
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How good is the error correction and subfolder (directory within directory) support? Is it supported by DiskSalv? How does the speed of access to a file compare to FFS? Can it be used on other devices, like Catweasel? Does it ramp up to HD floppies? Or is it a pebble on the superhighway of computing, best left squished between the treads of a tire belonging to a Dodge 1968 Super Bee heading for that curve in the road that it will never make?
Your metaphors are getting stranger and stranger the past couple days, Dan. You feeling alright? :)
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Dude,
An obscure file sysrem needs an obscure metaphor!
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How good is the error correction and subfolder (directory within directory) support? Is it supported by DiskSalv? How does the speed of access to a file compare to FFS? Can it be used on other devices, like Catweasel? Does it ramp up to HD floppies? Or is it a pebble on the superhighway of computing, best left squished between the treads of a tire belonging to a Dodge 1968 Super Bee heading for that curve in the road that it will never make?
You are mixing two things: The Filing system that organizes the disk into directories and files (OFS, FFS) and the exec device that transmits raw device blocks from the hardware to memory. That is, it is a two-layer design. With the proper mountlist, FFS can operate on any type of (block oriented) exec device, for example the scsi.device or the trackdisk.device. Or even the diskspare.device (or whatever its name was). DiskSalv does of course quite the same, it goes down to the device the filing system is mounted on. So yes, DiskSalv works on this floppy.
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I suppose the sarcasm got missed, much as the forest by the trees?
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Was it diskspare also that enabled HD floppies to be formatted to 1.9MB? Or am I getting my devices mixed up?
I remember using this to achieve 1.1MB capacity on my A1200 IIRC:
http://aminet.net/package/docs/hard/HiDensity
At least I think it was that. Oh, also, is it 'floppy's' or 'floppies' anyone?
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"your MOM." :snort:
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Was it diskspare also that enabled HD floppies to be formatted to 1.9MB? Or am I getting my devices mixed up?
I remember using this to achieve 1.1MB capacity on my A1200 IIRC:
http://aminet.net/package/docs/hard/HiDensity
At least I think it was that. Oh, also, is it 'floppy's' or 'floppies' anyone?
GCR encoding differs from MFM and was used on the PET/C64 floppy drives. There are advantages of MFM over GCR, but you can google that if interested.
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The Aminet reference for the HiDensity.lha is a bit odd; when I read the file's "readme" it takes into account that the early AT A1200's shipped with a HD floppy drive that could take some advantage of a HD floppy by using, what I assume from the device name, is a GCR format to give a boost on a 2 MB unformatted floppy a storage capacity of 1.1 MB.
Not exactly a plot for a Soap Opera on prime time TV, but a side note into more obscurity...
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The diskspare.device was acceptance replacement when I tried it on my Amiga in mid 90s however it was unstable on certain cheap and old disks. Since diskspare.device had to be loaded before it could be used it was usable only on HD systems. But when you have HD why use floppies?
IIRC when I only had 30MB harddisk on my A600 I used diskspare.device to store some lesser utilities to floppies. I was always short on disks so I wanted to cram more stuff.
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How could one not prefer a full head step over a half head step.
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How could one not prefer a full head step over a half head step.
Double your capacity, Double your error rate, or was that Double Mint Gum?
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How could one not prefer a full head step over a half head step.
When yo uhave HD you have no generally need for floppies anymore. If you dont have HD you are screwed anyway because you cant boot from sparedisk.device formatted floppy.
It was interesting experiment but higher capacity CD-R/RW were becoming mandatory in mid and late 90s.
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Perhaps because it was "ironical"
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The diskspare.device was acceptance replacement when I tried it on my Amiga in mid 90s however it was unstable on certain cheap and old disks. Since diskspare.device had to be loaded before it could be used it was usable only on HD systems. But when you have HD why use floppies?
IIRC when I only had 30MB harddisk on my A600 I used diskspare.device to store some lesser utilities to floppies. I was always short on disks so I wanted to cram more stuff.
The UK magazine Amiga User International distributed coverdisks formatted with diskspare.device, I think they did this from about '95. So you had to use diskspare if you ever wanted to read their coverdisks. They were crammed full of compressed goodies though, all 984KB's worth. I miss that magazine.
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Okay, I get the floppies could be setup (formatted) from 837k to 984K...
But what is the "normal" formatted number?
TIA
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You got 2 "normal" sizes available on the Amiga, on earlier KS1.x systems it's Original Files System with 837K and for later KS2.x systems it's Fast File System with 880K (if nothing else is specified I'll always go with DOS\3 FFS-INTL).
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Okay, I get the floppies could be setup (formatted) from 837k to 984K...
But what is the "normal" formatted number?
TIA
You can't boot a FFS floppy (880KB) from a 1.3 Kickstart, but you can use FFS floppy's from Workbench 1.3 with Fast File System installed (Workbench 1.3.2 or above has the FFS included).
You can boot a FFS disk from any 2.0 Kickstart or above Amiga. And of course, all Kickstarts can boot OFS (Original File System) disks (837KB).
Feel free to correct me if I'm wrong anyone, as I haven't used 1.3 for a number of years.