website/content/museum/r-f-t-kc-85-4.md

---
title: R.F.T. KC 85/4
categories:
- Computers
params:
  name: KC 85/4
  image: /media/museum/photos/rft_kc85_4_frontview_s1.jpg
  company: /companies/r-f-t
  company_name: R.F.T.
  tabs:
  - photos
  - hardware
  - links
  - docs
  forum_thread: 587
  photos:
  - title: LARGE VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/rft_kc85_4_system_s1.jpg
  - title: TOP VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/rft_kc85_4_topview_s1.jpg
  - title: LEFT & RIGHT SIDES
    subtitle: ''
    text: ''
    image: /media/museum/photos/rft_kc85_4_sides_s1.jpg
  - title: FRONT PANEL
    subtitle: ''
    text: ''
    image: /media/museum/photos/rft_kc85_4_front%20panel_s1.jpg
  - title: KEYBOARD
    subtitle: ''
    text: Same poor keyboard as the 85/3, badly conceived (i.e. the Return key) and unsuitable for fast typing.
    image: /media/museum/photos/rft_kc85_4_keyboard_s1.jpg
  - title: REAR PANEL
    subtitle: ''
    text: 'Same connectors as the 85/3: RGB and TV video output, and bus expansion.'
    image: /media/museum/photos/rft_kc85_4_rearside_s1.jpg
  - title: RFT PLATES
    subtitle: ''
    text: ''
    image: /media/museum/photos/rft_kc85_4_labels_s1.jpg
  - title: INSIDE
    subtitle: ''
    text: Same internal design a the 85/3
    image: /media/museum/photos/rft_kc85_4_inside_s1.jpg
  - title: MAINBOARD
    subtitle: ''
    text: |-
      Compared to the 85/3 version, the mainboard has been completely redesigned. Almost all of the ICs come from former Eastern Europe\
      **(1)** U880D CPU, Z80 equivalent\
      **(2)** 20 KB ROM chips 2x2764, 1x2732. One of them comes from ST Microelectronics, two others come from Eastern Europe\
      **(3)** 64 KB RAM chips, 4164 equivalent\
      **(4)** UB855D I/O chip, Z80-PIO equivalent\
      **(5)** UB857D display controller chip, Z80-CTC equivalent.
    image: /media/museum/photos/rft_kc85_4_mainboard_s1.jpg
  - title: DISMANTLED
    subtitle: ''
    text: Dismantling a KC85 isn't an simple task, mainly because of the three flat cable connectors which are not removable, also because all the cables are soldered. we gave up in removing the PSU. Repairing this computer shouln't be really easy.
    image: /media/museum/photos/rft_kc85_4_dismantled_s1.jpg
  hardware:
  - title: D002 BUSDRIVER
    subtitle: ''
    text: |-
      The Busdriver is an expansion interface which adds four additional expansion slots to the system, resulting in a total of 6 (4+2).

      Thanks to [WWW.KC-CLUB.DE](http://www.kc-club.de) for this picture
    image: /media/museum/hardware/veb_kc85_d002-busdriver_1.jpg
  - title: D002 BUSDRIVER
    subtitle: Opened
    text: |-
      We can easily notice the 4 expansion slots and their boards, as well as the dedicated power supply in the right part of the case.

      Thanks to [WWW.KC-CLUB.DE](http://www.kc-club.de) for this picture
    image: /media/museum/hardware/veb_kc85_d002-busdriver_2.jpg
  links:
  - title: Der KC85 - das modulare 8bit-ComputerSystem des veb mikroelektronik 'wilhelm pieck' mühlhausen
    url: http://www.mpm-kc85.de/
    text: German dedicated website
  - title: KC Club
    url: http://www.kc-club.de/
    text: Nice german site full of info!
  - title: UPKA
    url: http://www.upka.de/
    text: lots of documentations in PDF (German)
  docs:
  - title: KC87 & Z9001 MANUALS AND DIAGRAMS, IN GERMAN
    url: null
    cover: /media/museum/docs/couvs/vide.gif
    text: |-
      **KC87 & Z9001 MANUALS AND DIAGRAMS, IN GERMAN**\
      written by Robotron

       compiled/archived by Compiled/archived by Thomas Stein\
       type of document : PDF\
       source : Thomas Stein
  related:
  - /museum/r-f-t-kc-85-3
  - /museum/robotron-kc-85-1-z-9001
  - /museum/robotron-kc-87
  oc_id: 598
  source:
    url: https://web.archive.org/web/20230603015019/http://www.old-computers.com/museum/computer.asp?c=598
    date: '2023-06-03'
---

The KC85/4 was the last one of the KC85/x series. Although it doesn’t look quite different, some internals changed. The whole design changed a bit, and software which used to access hardware directly, sometimes didn’t work any longer, as some addresses changed.

Also, memory was expanded to 64 KB, and the whole memory could be used by software. The ROM increased to 20 KB. The CAOS system offered printer support for most of the available GDR printer models.

There are two expansion slots, which could be extended to four through an expansion set-top.\
\_\_\_\_\_\_\_\_

Information kindly provided by **Stefan Goehler**.