This is an article culled from archive material, circa 1997.

MIDI Manager dates from the time (1989?) when
Apple Computer believed
that the professional music market was important and worth of some
respect. MIDI Manager (or, more correctly, the
MIDI Management
Tools) provided an extension to the Macintosh system which allowed
MIDI applications to address the hardware in a high-level, portable
manner. In fact, MIDI Manager applications could even communicate with
one another, transparently, and could (in theory) work with new types
of hardware, so long as the hardware vendors provided MIDI Manager
drivers for their devices. MIDI Manager provided data transfer services
(including message parsing), and some respectable timing functions,
including timecode conversion.
In fact, MIDI Manager worked extremely well, and I still make heavy use of
it. It was small, simple and elegant. Politically, however, Apple managed
to shoot themselves in the foot with it.
Apple Corps., the Beatles'
recording company, immediately took Apple to court over copyright
infringement, since Apple Computer had licenced the name "Apple" for use
in non-musical products. By the time the court case was concluded,
several things had happened: MIDI Manager's developers had left,
Opcode had developed
OMS, and Apple
had lost interest in the music market.
(The illustration shows MIDI Manager's
PatchBay application (top)
with OMS emulating a MIDI Manager driver (bottom).)
These days, everyone has a MIDI operating system, and all the punters
want lots of options, lots of features and lots of cool, coloured icons.
Personally, I think MIDI Manager had it about right: small, simple and
reliable. Other vendors could learn something here.