While we do not have any German computer in an operable state, we do collect some documents on German computers which are not universally available. Most of these documents are in German language, no translation provided.

Siemens S2002 (1959)
Befehlsliste (PDF, 945kB)
Simulator for the S2002 for MS-DOS including Triplex-ALGOL 60 compiler and example
This simulator was written by John G. Zabolitzky in the FORTRAN language and runs under MS-DOS. The source is included so adaptation to other operating systems is easily possible. Included with the hardware simulator is the machine code for the Triplex-ALGOL 60 compiler Alcor Mainz S2002. A triplex number is a machine representation for real numbers in the form
[min value, standard value, max value]
where all rounding errors are propagated through all computations, enlarging the [min, max] interval while going on. The language is described in

Apostolatos, N.; Kulisch, U.; Krawczyk, R.; Lortz, B.; Nickel, K.; Wippermann, H.-W.: The Algorithmic Language Triplex-ALGOL 60. Numerische Mathematik 11, pp. 175-180, 1968.

Applications are found here.
Interval arithmetic has not become popular since the strict [min, max] computation disregards the statistical nature of roundoff noise. The standard arithmetic in most cases known is very significantly more accurate than the interval arithmetic result might indicate.

Goettingen G2 (1960)
Befehlsliste (PDF, 14MB, bad contrast, therefore much noise)

Muenchen PERM (1952)
Original-Fotografien

Telefunken TR440 (1971)
Große Befehlsliste TR440