[Lammy]

> The disadvantage of this technique was that there was no interoperability with PC diskettes possible, at all, even with software changes. For the Macintosh, this changed with the introduction of the Macintosh SE in 1987. The Macintosh SE had a new floppy drive controller, the ‘SWIM’ (Super Woz Integrated Machine) and a new disk drive which could read and write both Macintosh CLV and PC CAV formatted diskettes.

Pardon my nitpick, but there were two versions of the SE and the author has the dates mixed up here. The original 1987 model had the same disk capabilities as the Mac Plus except it could have two of them installed internally instead of just one on the Plus. Or one 800K drive and an internal SCSI HDD in the other bay — your choice! (Mine actually has all three thanks to a third party internal HDD bracket!)

The FDHD (floppy disk high density) version was released in 1989 as a standalone computer and also as an upgrade kit for the original model containing one (1) SuperDrive, SWIM, updated ROM, and little “FDHD” and “800K” badges to put next to the upgraded and remaining original drives respectively.

See https://bylenga.ddns.net/FDHD/MacSEservice.pdf#page=87

[ForOldHack]

SE and SE HD, and if you took the 400 or 800k version of the second floppy from your Mac plus, you could use it as a third floppy. I tried this on an SE and it worked, but never tried it on a SE HD. I thought that some early MacIIs had iwm chips in them, and with A FD HD upgrade you got a SWIM chip and a pair of ROMs to put in.