website/content/museum/buromaschinenwerke-zella-mehlis-cellatron-8205.md

---
title: BÜROMASCHINENWERKE ZELLA-MEHLIS Cellatron 8205
categories:
- Computers
types:
- Professional Computer
origins:
- Germany
years:
- '1963'
cpus:
- Discrete components
params:
  name: Cellatron 8205
  image: /media/museum/photos/veb_8205_system_s1.jpg
  company: /companies/buromaschinenwerke-zella-mehlis
  company_name: BÜROMASCHINENWERKE ZELLA-MEHLIS
  specs:
  - label: NAME
    value: Cellatron 8205
  - label: MANUFACTURER
    value: Büromaschinenwerke Zella-Mehlis
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: Germany
  - label: YEAR
    value: '1963'
  - label: BUILT IN LANGUAGE
    value: None
  - label: KEYBOARD
    value: Primary keyboard
  - label: CPU
    value: Discrete components
  - label: SPEED
    value: Unknown
  - label: RAM
    value: 4096 x 33 bits on magnetic drum memory
  - label: ROM
    value: None
  - label: TEXT MODES
    value: No display but lamp array
  - label: SIZE / WEIGHT
    value: 'required space: approx. 9 square meters'
  - label: BUILT IN MEDIA
    value: 2 paper tape punchers, 1 paper tape reader
  - label: OS
    value: No OS
  - label: POWER SUPPLY
    value: 1500 VA power consumption
  - label: PRICE
    value: Unknown
  tabs:
  - photos
  forum_thread: 1002
  photos:
  - title: LARGE VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/veb_8205_system_s2.jpg
  - title: MAGNETIC DRUM
    subtitle: ''
    text: The magnetic drum memory rotated at 18,000 rpm. It was organised in 128 tracks with 32 sectors each, every track having a read/write head of its own. In total, this resulted in a capacity of 4096 words of 33 bits.
    image: /media/museum/photos/veb_8205_drumdiagram_s1.jpg
  - title: PS 2 MANUAL COVER
    subtitle: ''
    text: |-
      Full reference of this book:\
      *Gerd Ehrke et al. "Problemorientierte Programmierung für den Kleinrechner C 8205: Die algorithmische Sprache PS 2". Verlag Die Wirtschaft, Berlin.*
    image: /media/museum/photos/veb_8205_ps2manual_s1.jpg
  - title: 'BLOCK DIAGRAM #1'
    subtitle: ''
    text: |-
      Block diagram of the central unit.

      German to English translation:\
      Hauptspeicher - main memory\
      Operand - operand\
      Adressenwähler - address selector\
      Akkumulator - accumulator\
      Ergebnis - result\
      Rechenwerk - arithmetical unit\
      Befehlsregister - command register\
      Adressregister - address register\
      Operationsregister - operation register
    image: /media/museum/photos/veb_8205_blockdiagram_s1.jpg
  - title: 'BLOCK DIAGRAM #2'
    subtitle: ''
    text: |-
      Block diagram of the complete system.

      German to English translation:\
      Tastatur - keyboard\
      Schreibwerk - printer\
      Lochbandleser - paper tape reader\
      Lochbandstanzer - paper tape puncher\
      Kanal - channel\
      Zentraleinheit - central unit\
      Rechenwerk - arithmetical unit\
      Leitwerk - control unit\
      Trommelspeicher - drum memory\
      Stromversorgungseinheit - power supply unit
    image: /media/museum/photos/veb_8205_blockdiagram_s2.jpg
  oc_id: 1028
  source:
    url: https://web.archive.org/web/20221205112301/http://www.old-computers.com/museum/computer.asp?c=1028
    date: '2022-12-05'
---

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](http://retrocomputing.ch/) for information and pictures.

<table> <tr> <td></td> <td>We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.</td> <td></td> </tr> </table>