B > BÜROMASCHINENWERKE ZELLA-MEHLIS > Cellatron 8205     

In 1963, engineers at the Institut für Maschinelle Rechentechnik (institute for machine computation technology) in Dresden, GDR (ex-Eastern Germany) finished the D4a. The D4a had been developed on the basis of the Kleinrechenautomat Dresden 1 (D1) from 1956. The system was then manufactured by the VEB Büromaschinenwerk Zella-Mehlis in three versions, under the name Cellatron 8201, 8205, and 8295 Z. About 3000 exemplars were produced. The D4a is seen as the first PC of the GDR.

By the way, VEB is short for Volkseigener Betrieb and means as much as "factory belonging to the people".

The C 8205 central unit was comprised of the Leitwerk (instruction counter, instruction register, and address decoder), the Rechenwerk (accumulator and math operations), and the Trommelspeicher (magnetic drum memory). The former two subsystems were realised as discrete circuits including approximately 400 transistors and 2000 diodes.

Working memory was realised with a magnetic drum memory providing 4096 words of 33 bits. Moreover, the system was comprised of a command desk with keyboard, lamp array for displaying operational states, switches for locking certain tracks of the drum memory, two paper tape readers and one puncher, and a typewriter-like printer. It needed about 9 sqm space in an air conditioned and noise insulated room. Power consumption was 1500 VA.

The system could be programmed in pure machine code, or in interpreted pseudo-code using a program called GIPS I, Gleitkomma-Interpretationssystem einfacher Wortlänge, i.e. floating point interpretation system with single word length. It simulates floating point arithmetics as well as a number of pseudo data registers. The GIPS I interpreter had to be read into memory before use.

Moreover, it was possible to program the system in PS 2, which probably meant programming language 2. It was developed by VEB engineers. This language implemented various data types, mathematical operations, I/O commands, and control statements equivalent to GOTO, IF...THEN GOTO, labels, subroutines, and FOR-loops. The source program had first to be punched on paper tape, and then compiled. As the PS 2 compiler occupied the complete memory, the resulting object code (in GIPS I format) was immediately punched out on paper tape. After that, the object code could be read and run with the GIPS I interpreter in memory.

The picture shows the C 8205 model.

Thanks to Roman von Wartburg and his site for information and pictures.