There is definitely something different about Buchla modular synthesizers.
One can delve into this and find many opinions, as well as endless lore (a
small fraction of which my be true, but much is exaggerated) about "east cost vs.
west coast" synthesis, etc. But there is no doubt that Buchla has its share of
unique innovations, quirks, and a definite "point of view". I find some
of these interesting, but personally I find myself fascinated by the more rare
(and messy) Buchla non-modular instruments.

I won't get into the full history here, but let's talk about three Buchla
integrated, hybrid (analog/digital) instruments. Let's also look at the prospect of
hearing, running, or emulating these.

1. The Buchla 400 (https://www.vintagesynth.com/misc/buchla400.php) -
An evolution of the 200 voice system with embedded computer control.

2. The Buchla Touche
(https://www.vintagesynth.com/misc/buchlatouche.php) - A concession to
lovers of the tradition manual keyboard, with a similar architecture
to the 400.

3. The Buchla 700 (https://www.vintagesynth.com/misc/buchla700.php) -
The culmination of both fully integrated control (with touch-
sensitive input for nearly every parameter), focusing on a rich FM
synthesis architecture.

Restorations

These instruments are exceedingly rare, even by Buchla standards.
Particularly for the Touche, perhaps only one or two exists "out
there". These aren't something that can just be found on eBay.

1. The Buchla 400 has had a restoration done by D.A. Wilson (aka
Hideaway Studios,
https://forum.vintagesynth.com/viewtopic.php?f=1&t=80892&p=758119&hilit=hideaway+buchla#p758119)

2. The Touche may only have one (?) known to be operational, restored
by Richard Smith (aka "Shasta Cults",
https://daily.bandcamp.com/features/shasta-cults-new-lp-was-created-completely-on-the-buchla-touche).

3. There were a few more Buchla 700s made, but they are difficult to
keep running. Like most Buchlas, the runs were too small for mass
production techniques and there is a lot of variation in the hand
assembly. See https://lanterman.ece.gatech.edu/buchla700/ and
http://randomvoltage.com/700/.

Recordings

1. D.A. Wilson recorded the Buchla 400 he restored
(https://soundcloud.com/hideaway-studio/buchla-400-awakens).

2. Shasta Cults released a whole album recorded on the Buchla Touche
(see earlier link). There is a video recording available at
https://www.youtube.com/watch?v=vVzaCq8foUw&list=WL&index=151.

3. Shasta Cults has also recorded an album with Buchla 700,
_Configurations_
(https://www.factmag.com/2019/08/02/shasta-cults-configurations-album/).

Emulations

1. I am not aware of a Buchla 400 emulation, although I'm guessing the
computer control has some similarities to what wound up in the Touche.
So, generations of PATCH, MIDAS, FOIL (and hence some commonality with
HMSL).

2. I am not aware of a Touche emulation, but as I've mentioned before
(gopher://sdf.org/0/users/kurtgeis/phlog/20230611-HMSL.txt), you can
run versions of HMSL that have common lineage with some of its
software.

3. The Buchla 700 has a couple of preservation projects. An open
source work in progress can be found at https://bob.lopatic.de/. There
is a commercial emulation (really, more like a reboot or virtual synth
in the spirit of the 700) from modosc that runs on iOS
(https://modo.sc/id700/).

As hard to find and cantankerous as these instruments are, they all
have one thing in common with all Buchla instruments: they sound
amazing. Have a listen of some of the recordings at least.