The small computers of the row KC 85 were built for William Pieck (HC900, KC 85/2, KC 85/3, KC 85/4) starting from 1984 in the GDR by the VEB Robotron (Z9001, KC 85-1, KC 87) and/or by the VEB microelectronics "„and were at the furthest common computer of the GDR. The manufacturer thought first of the hobby and private sector, however most computers for the national education were lodged a complaint. To short before the end of the GDR (approx. 1988) these computers were with difficulty available thereby for private people. Also the high price (4300 M for the KC85/3) ensured for the fact that "„the small computers found "“hardly their way into private households.

Technology

KC 85/2 to KC 85/4

It was based on the 8-bit CCU U880 (a Z80 clone) with 1 up to 2.5 MHz clock frequency. The typical application of the computers was a KC 85/3 with 16 KByte RAM (expandable with auxiliary modules), inserted ROM BASIC, attached tape recorder for the data storage and connection at one as monitor used televisions (over coaxial cables, FBAS or RGB). The ROM BASIC and the small letters were missing to the KC 85/2. The KC 85/4 came with 64 Kbyte RAM (bankswitched), ~40 KByte image refresh storages and improved diagram possibilities, which were hardly still used however by the collapse of the GDR. All KC 85 from was diagramable; the screen resolution amounted to of pixels, however "„the color dissolution was substantially smaller "“; in a pixel rectangle of pixels there could be only one foreground color (from 16 possible) and a background colour (from 8 possible); this restriction was reduced with the KC 85/4 to a rectangle from pixels and additionally could "„more genuinly a "“color mode with 4 colors and without delimitation be switched on. Only with the KC 85/4 the disturbing peculiarity of the KC-row was omitted to draw during the structure of diagram disturbing strips over the screen.

Most KC-users loved its KC, some until today (see anecdotes at the end this article), although the architecture of the HC900 was everything else as perfect: the screen control (with counter circuits realized - no 6845) was to be programmed painful. Substantial system functions became with PIOs (e.g. Bankswitching) and CTCs (cartridge interface, flashing, sound) realizes. Sound about gave it by two CTC channels with flip-flop downstream. Extras such as Blitter or Sprites were missing completely. CAOS and BASIC were quite comfortable, but (partly unnecessarily) slowly, so as if someone would have simply checked off in product requirement specifications: "„F-keys "“, "„multicolored "“, "„sound "“and itself not further cared for the fact that scrolling and CLS (the BASIC instruction for screen deletion) lasted second-long. This improved itself only with the KC 85/4 clearly. For the end of the series until 1988 there were floppy Disc drive assemblies as auxiliary modules (360kB FD) and some standard interfaces (center NIC savings allele printers and RS232C and/or V.24)

KC 85/1 and KC 87

The KC 85/1 (successor of the Z9001) was built by Robotron and had up to the processor and the designation hardly something with the KCs to do, although the fiction of series was maintained by the common BASIC dialect and same cartridge recording format. The KC 87 was an improved KC 85/1 with BASIC in the ROM. These computers there were also with color option, it offered however no pixel diagram, but only text mode pseudo diagram.

Programming languages

The KC85 could be programmed in machine language and (before the KC85/3 only with an auxiliary module or a RAM BASIC of cartridge) also with a BASIC dialect, clearly richer was than for instance the BASIC in the C64. Contrary to most home computers the system always started with the operating system CAOS (rather a better monitor); BASIC had to be called from this monitor explicitly, if it was present at all in the ROM. The monitor commands could be very simply extended by assembler programmers.

Further ones, but few common programming languages for the small computers were Pascal and Forth. In the last years of the GDR a diskette essay for these computers was actually built. Thus then also CP/M name for it could: "„MicroDOS "“) and software for it to be used.

Also for the KC 85 there was the programming language BASICODE. It is a BASIC dialect compatible for a set of computers, whereby programs for BASICODE became to transfer also in the broadcast.

Hobby projects approximately around the KC

Popular self-building projects were:

• Connection of another keyboard
• RAM disk
• Interface modules
• Word processing systems
• Connection of electronic typewriters as keyboard and printers (for example Erika type wheel type writer S3004)

In addition there were model tests to realize industrielle tax tasks (programmable controller, SPS) for training purposes with the small computers.

Different

• Connection diagrams: The diagrams were revealed, and there were numerous additional circuits and programs. Particularly the magazine took care of "„radio amateur "“the mini-computer, it published circuits, listings and information about computer clubs. Further circuits and reference appeared in the magazine "„Practic "“.

• Modules:

• Thermal problems: The KC 85/3 got along without exhausts, however probably urgently such would have used. Whether it was now at the discrete structure of the diagram control or because of eddy currents in (also still black) the housing, anyhow the equipment became very hot and in the summer regularly unstably. Passive cooling by external exhaust helped.

• RESET: By a feature in the ROM of the KC 85/3 was possible it to intercept "“and for the user for example a sufficiently arrogant message present the RESET key "„. However most programs were content to let with RESETS simply all data of the CAOS delete (normally and with the KC 85/4 memory contents remained, cold weather starting with RESETs had specially to be requested - comparably as with Apple the II, but clear difference to other western home computers, with which the standard behavior was cold weather starting).

• Printer: Diagram-able matrix printers were produced in the GDR, were however hardly available over the free trade. Most copies were exported into the FRG and driven out there under the source mark privilege. The electrical typewriter Erika S3004 likewise built in the GDR could be used also as printers; however was a type wheel type writer. By persistent programming ("“."” and a quantity of micro steps was thereby involved) could diagrams be also printed (pseudo diagram). By late mains voltage increased in the Federal Republic got broken many of the typewriters S3004, since they were appropriate as for overvoltage rather for under.

• Space bar: The space bar was used for different plays and broke through after some time proper. Notoriously here the play was Ladder.

• REM: In the broadcast of the GDR there was a computer ending "„REM "“, which was very popular. Beside programming courses ("„basic for progressing "“) and Tipps and cheat was the special in the fact that over the ether software programs were radiated. One could along-cut and into the KC load the radiated tones later by means of tape recorders.

Lines

With the small computers there were several different rows:

• LC80: (LC von Lerncomputer) a plate computer, only machine language, only with pocket calculator keyboard and 7-Segment-LED
• Z1013: Kit (RAM basic, assembler, flat transparency keyboard, connection for black-and-white television, auxiliary modules)
• HC 900: (HC of home computer) later in KC85/2 renamed (external keyboard, pixel diagram, connection for colour television sets), operating system HC-CAOS (cartridge Aided operating system)
• Z 9001: later in KC85/1 renamed (inserted, very painful keyboard, pseudo diagram, connection for black-and-white televisions), follow-up type: KC87
• KC compact: The gift to 40. Republic Republic of, very small numbers of items, CPC clone; keyboard came with a tidy, into the housing integrated; confusing possibly it is that housings and keyboard (not however electronics) were used also with the BIC and with the luxury keyboard for the KC 85, offered by (late).

Articles in category "KC 85"

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Related Websites

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• KC 85 - Wikipedia, the free encyclopedia
  There were two main lines in the KC 85 series, the KC 85/2 (project name HC 900) to ... The keyboards were of poor quality (the KC 85/1 used an integrated ...


• KC 85 - Wikipedia, the free encyclopedia
  The colors were not paletted in any KC before the KC compact. There was no "text mode", everything had to be painted; this and the awkward video RAM layout ...


• KC-85/1 from FOLDOC
  KC-85/1. <computer> A commercial home computer from East Germany. The KC-85/1 runs at 2.45 MHz and uses a Z80 clone CPU. The computer allows for only ...


• Links zum Thema KC 85 / DDR-Computer
  KC 85 ist der Name einer Home-Computer-Serie aus der DDR. Die beiden letzten Modelle, KC 85/3 und 85/4, haben noch heute einen kleinen Freundeskreis. ...


• OLD-COMPUTERS.COM : The Museum
  NAME, KC 85/4. MANUFACTURER, RFT. TYPE, Home Computer. ORIGIN, Germany. YEAR, july 1988. END OF PRODUCTION, Somewhere around 1990 ...