If you insert a Lisa disk into your Mac, it will not recognize it as having a valid file system and it will offer to format it for you. Formatting will wipe any data on the disk. Just because your Mac doesn't recognize the data on a floppy doesn't mean that there isn't any data there! It could be a Xenix, or Lisa Office System formatted disk! Make sure you know where it came from.
Also, you should not reuse Lisa disks as Mac disks. The 400K single sided drives the Lisa uses have a foam pad on the top where the drive head is, this may wear away the magnetic media on the top surface of the floppies, making them unreliable as double sided floppies.
You'll need one of two applications. (Ideally you'll have both.) Apple's Disk Copy 4.2 program (later versions will not be useful) or Apple's DART program (version 1.5.4 was the last released).
Do not use later versions of Disk Copy, nor anything that comes with Mac OS X! These do not support the extra 12 bytes of tag data which is vital for use with your Lisa. Some of the later versions of Disk Copy claim to be able to convert DART disk images into Disk Copy images - DO NOT USE THIS FEATURE it will appear to work, but it will strip off the vital tag data, which will prevent the disks from booting on a Lisa!
Instead, obtain both the DART and Disk Copy 4.2 programs, since you may find disk images in either flavor when trying to locate software for your Lisa.
Between the two, when making your own disk images, you should use Disk Copy 4.2 as it's more compatible and friendly with your Mac and Lisa despite the fact that DART supports compression.
An old Macintosh that has a floppy drive capable of using 400K or 800K floppies. Most older Macs will work, as will most early PowerPC's. (i.e. Mac IIcx, IIci, IIsi, Plus, SE, SE/30, PPC7100, etc. will all work, as will some early 68K and early PPC PowerBooks with floppy drives. A PowerMac G3 has been tested using Disk Copy 4.2 and it also works.) Those Mac clones that do not support 800K floppies will not work.
See addendum for some comments about preferred hardware and software.
For Lisa disks (or 400K disks for use with MacWorks), you can use any 3.5" SS/DD floppies - that is single sided, double density. For 800K disks for use with MacWorks Plus/II, use DS/DD (Double sided, double density).
See addendum for some comments about re-using previously formatted floppies in a Lisa.
Your Lisa floppies will NOT be mountable for reading/writing as a file system in your modern Mac with the exception of floppies used with one of the varieties of MacWorks.
All the other Lisa file systems are not directly readable by a Mac, and the use of other tools (such as the terminal program) or the Lisa Migration Kit is needed.
Depending on your Macintosh hardware/software, you may be able to make images of your Lisa disks using DART or DiskCopy, and FEdit Plus and other software will allow reading/writing these disks at the byte level in hexadecimal or ASCII.
The System versions that run under MacWorks XL predate the HFS format, so all of the floppies used with this environment are in MFS format.
If you're trying to read/write an MFS floppy, older Mac OS's such as 6.0.8 will be able to mount it as "read only".
System 7 and above do not support reading of MFS floppies at all, inserting such a disk will invoke the "Do you want to initialize?" dialog.
800K floppies used by MacWorks Plus/II are usually in HFS format, and can be read and written to by more recent Macintosh Systems than the MFS format.
Note that MacWorks Plus (1.1h and earlier) have a bug involving the detection of the HFS vs MFS floppy formats. MacWorks Plus assumes all 400K floppies are MFS, and all 800K floppies are HFS, which is not always correct. Although these are the default formats, the opposite can be invoked by holding down the option key while erasing/initializing the floppy. As a result, these non-standard floppies are not interchangeable between MacWorks Plus and other Macs, so any data on them should be copied to "normal" floppies. At least one commercial application was shipped on such a non-standard floppy, which would be corrupted when used with MacWorks Plus.
This bug was corrected in MacWorks Plus II (2.0 and up), which correctly identifies HFS/MFS floppies according to the initialization format rather than the size.
Simply launch either Apple Disk Copy 4.2 (preferred) or DART (not recommended if Disk Copy 4.2 is available) and select the options for making a disk image, then, when prompted insert the Lisa floppy. Once it's done, save the disk image to your Mac's hard drive.
Launch Apple Disk Copy 4.2 (or DART 1.5.4), and load the disk image using the file menu (or button.) Then click on Make copy, and when prompted, insert a blank 3.5" floppy. DC42 or DART will format, then restore the data and verify it, and finally eject the floppy.
On Macintosh II and later computers, DART will make disks that will be marginal or impossible to read on Lisa hardware. In this case, duplicate the disk onto itself using Disk Copy 4.2 to convert the disk to the 5 bit-slip-FF format required by the Lisa hardware. See the section below on Preferred hardware and software for more information.
These depend on the operating system.
For trouble-free results, use another Lisa or a Macintosh 128K, 512K, 512KE, or Plus for making disks for use in a Lisa.
Although newer Macintosh models may appear to make disks usable on a Lisa, there are circumstances where some data will not be readable by Lisa hardware. In these cases, using DiskCopy 4.2 to duplicate the disk onto itself is likely to make the disk usable on a Lisa.
If you must use a Macintosh II or later, use:
To check whether a disk made in another machine is readable on a particular Lisa, mount the disk using FEdit Plus on the Lisa running under some (any) version of MacWorks and have it read every sector (eg. by searching for something, or put a weight on the mouse button). An I/O Error indicates some sector could not be read.
Technical Explanation: The Lisa floppy disk controller (FDC) anticipates 5 bytes of "bit-slip-FF" to synchronize its state machine to an address mark or data mark. The Macintosh FDC was improved to need only 3 bytes of bit-slip-FF, however use of this improvement was only implemented in the Macintosh II ROM and later.
The result is that some sectors of a disk written by a Mac II or later may not be readable by a stock Lisa FDC. This includes disks initialized on such a machine, as well as any file/directory data written on such a machine.
The rare exception is DiskCopy 4.2 which bypasses the floppy driver and accesses the floppy hardware directly. It happens that DiskCopy 4.2 writes 5 bit-slip-FF's even on hardware as recent as the beige G3 desktop, and regardless of whether the source disk/image used 3 or 5 bit-slip-FF's.
The number of bit-slip-FF bytes on a particular floppy can be determined using a PC with the Central Point "Deluxe Option Board", which has the capability of reading individual magnetic transitions on a disk.
For further information about bit-slip-FF bytes and the GCR encoding of Apple floppies of this era, see the Apple II book "Beneath Apple DOS".
MacWorks Plus II includes a Programmable Frequency Generator (PFG) that provides real-time adjustment of the FDC timing under software control, enabling MacWorks Plus II to read almost all Macintosh disks written with 3 bytes of bit-slip-FF.
The Lisa 2/10 aka Macintosh XL has a slightly different FDC than the earlier Lisa. One of the differences is that using an XL to re-initialize a previously formatted floppy almost always fails.
For best results with an XL, only new, uninitialized/unformatted floppies should be initialized. Previously used floppies should be re-initialized on another machine, or can be re-used by putting their contents in the trash.
Using a bulk eraser is an alternative when new floppies are unavailable.[LisaFAQ] > [Hardware] > [Floppy, Twiggy, and Tape media used with the Lisa] (Comment on this answer)