found these that describe it a bit more:
http://www.cc-computerarchiv.de/CC-Archiv/edv … -itos-7_92.html
http://www.horniger.de/computer/ctm/index.html
sounds like it runs AIX and you need CTM 95 WS-BK terminals.

If it has 68030 CPUs it will not run AIX, even if the 3 position keylock, the yellow reset button and the LED display look pretty much like an IBM RS/6000.
you should be able to connect some serial terminal or PC with terminal emulation software like terraterm to the COM port if there is still an UNIX-like OS installed. If you can post pictures of inside and back, identification may be easier.
eisapc

Definitely needs a terminal. Keep in mind RS232 is not the only kind of standard for hooking up terminals.

eisapc wrote:

If you can post pictures of inside and back, identification may be easier.
eisapc

I added a dropbox link in the original post with some higher res pictures (uploading a large amount of pictures here is not that convenient).

HanJammer wrote:

Definitely needs a terminal. Keep in mind RS232 is not the only kind of standard for hooking up terminals.

I was expecting to see "something" on the serial port, but nothing came up (tried different baud rates / flow controls / settings). Even if it cannot interpret the data, or a specific terminal is needed I should be able to see garbage (bytes on the RX/TX pins).

I was using a null-modem cable (db9 serial 2x female) between the serial port of the Peacock and a windows machine. I used Win98 hyperterminal to connect via the COM port. I also tried it on my macbook using an usb -> serial adapter with the null modem in between. But nothing shows up.

I wouldn't assue it's standard RS232. Even today devices using serial connection and DB9 plugs but they won't really work without propertiary cables and such... I would test it with logic state analyzer first, just to avoid damage.
Contacting this guy who has the website mentioned above seems like the best thing to do (icke@horniger.de), also this guy: https://www.youtube.com/user/bytebender/videos seems to have a collection of working ComputerTechnik Mueller stuff.