Hi All,
I've been a long-time "stalker" of these forums and have learned quite a bit in that position. This is my first post with an actual question…
I'm wondering if anyone has encountered the old (pre-1999) Single Sided or Double Sided Double Density disks during an investigation? These are the 400k and 800k flavor of floppy. I'm currently working on a case that involves them but I'm at a loss as to how they can be extracted off the disks and onto a modern platform.
From the research I've done so far I've surmised that these disks use a special kind of recording technique to format the disk. This technique involved speeding up or slowing down the speed at which the floppy spun in the drive, allowing more data to be placed onto it. Because of this, you need a floppy drive specifically designed to handle the disks. I've found that there was an external floppy drive called the SuperDrive but this was discontinued in 1994. An internal version of the superdrive later became a standard in nearly all macs up until 1998 - the last model being the Power Macintosh G3 (the dirty looking beige one).
All of that said, I'm at the point where I don't think it is possible to pull the data unless I can get my hands on one of these older macs. And lets say I do get my hands on one of these old machines - how would you recommend getting the data from the floppy to a modern system while leaving everything as intact as possible?
I should also say that my experience with Mac's is limited at best. I understand the basic OS and differences between PCs, but have not spent much time using them or working with.
Any input/advice would be greatly appreciated.
Thanks in advance!
We work with old technology by keeping it around on the shelf. We have a huge amount of space that got devoted to old Macs, tape drives, stacks of old SCSI boards, etc.
I am sure you can find what you need on ebay.
The Mac 400/800K disks were 80tpi, but they have 5 speeds of rotation. The intention was that the media to head speed was fairly constant between the inner tracks and outer tracks. The raw data could be read with standard 96 tpi drives, as long as the decoder could handle different data rates.
However, the disks did not use MFM or even M2M for data recording, but a GCR system, unique to Macs, an similar to Apple II computers. Just plugging a super drive into a PC will not work.
The only two ways I am aware of to read the disks are with an old Apple, or if you can find someone with an old Lynx Converter (in USA) or InterMedia disk converter else where in the world.
Once you have a way to read sectors, the Mac disk is the same structure as the 1.44MB disks
NOT with standard hardware.
Apart a Mac (that would be probably the easiest and cheapest option) the good ol' catweasel or Central Point CopyIIPC boards (Deluxe Option Board) should be able to do that
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Whilst the DOB is a thing of the past, a Catweasel should be still available
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The fact that Mac 400/800K is supported Read Only should be a plus for your case.
jaclaz
Agree with both the above posts variable speed with Group Code Recording as opposed to standard MFM on PC floppies. We used to use (backin my DR days over 10 years ago) the catweasel board. Worked well back then.
If you find an old mac that can read it, it will probably have Disk Utility installed on it, which you can use to make a DMG… although it'll be an older format of DMG.
Jon
Thank you so much for the info, folks! Specifically, jaclaz.
The Catweasel looks like a perfect solution to avoid storing the ancient machines that BitHead mentioned. Spare office space in NYC gets pricey roll
Thanks again for the input everyone!
Thank you so much for the info, folks! Specifically, jaclaz.
One of the rare occasions when having been around for some time turned out as experience instead of aging. wink
A man who carries a cat by the tail learns something he can learn in no other way.
lol
To keep things as together as possible and for future reference, these guys
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are about starting the production of a new board, USB connected
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jaclaz