Robotron KC87 (KC 85/1, Z 9001)

In all Eastern Block countries Eastern Germany had a very good location, allowing for better technology development. It was very hard to buy western electronic components, but contrary to e.g. Soviet Union it was possible. In 1980s many home computers have been designed in GDR, they were usually incompatible with each other. Many plants in Robotron combinate manufactured different home computers.
In 1984, Dresden Messelektronik factory started manufacturing Robotron Z9001 computer. It was a small computer with 16K of RAM and Z80 CPU. It was expandable with 4 modules. In 1985, after releasing of KC85/2 by factory in Muhlhausen, they renamed Z9001 do KC85/1, to complete series. Of course KC85/1 was totally incompatible with KC85/2 or /3.
In 1987 Dresden plant rebranded KC85/1 to KC87 and manufactured it until 1989.
It was quite robust computer system, first units had monochrome screen adapters, later had color (one joystick port was modified to become RGB output and both joysticks shared the same connector). Screen adapters were installed on small expansion boards inside computer. Earlier units had no BASIC in ROM, so it had to be loaded from tape or provided in external module. During development, computer got many improvements: BASIC in ROM, K565RU6 RAM chips (like 4116, but they don't need 12V and -5V) or extended I/O port.

Manufacturer VEB Robotron Messelektronik  "Otto Schon" Dresden (part of Robotron kombinat)

Origin East Germany
Year of unit 1987
Year of introduction 1984 (As Z9001)
End of production 1989
Speed 2,5MHz
RAM 16kB
ROM 16kB
Colors: 16 (or monochrome)
Sound: Simple beeper, built-in
OS: KC87 OS (and Basic)
Display modes: 40x24 character/semigraphic mode  


Media: Magnetic tape

Power supply:


Built-in semi-switching power supply giving +5V, -5V, -12V, +12V DC. Later units used +12V DC only for TV modulator and -5V for tape amplifier, -12V is unused in them.

Rating of Power Supply is:
+5V 2-3A
+12V 200mA
-5V 100mA
-12V ???
(this is for the latest KC87, first Z9001 need +5V at 3.5A, +12V at 500mA, -5V at 100mA and -12V at 150mA)

I/O: TV RF out
Tape In/out
1 connector for 2 joysticks
User I/O connector
4 modules expansion
(earlier there were 2 joystick connectors, one instead of RGB connector)
Possible upgrades: Modules
Peripherals in collection:
 - RFT LC-R tape recorder
Software accessibility: TOSEC

My unit came in after-service state, but it was "serviced" by some moron many years ago and then stored in a basement. During servicing it has been opened, then faulty memory chip has been replaced and unit has been reassembled, then turned on. Because someone missed +5V and +12V wires, I had to replace CPU, EPROMs and about 75% of logic before it turned on. 12V blown only one chip of RAM. The replaced one.

If you want to diagnose it, look how GRAPHIC led behaves when you turn it on. It should stay off or blink quickly, being lit when PIO is uninitialized. If it lights steadily, it usually means that CPU can't initialize PIO - CPU is not working or CPU/PIO/Logic is bad.
East German ROMs are also prone to failures.

Contents Loading programs Making cassettes Pinouts Links

Loading programs

After powering up, the computer should display garbage on screen, then clear it (by scrolling upwards) and output "robotron Z9001 OS" prompt. Then the following commands may be used:

BASIC - runs Basic from ROM. Asks for MEMORY END, usually this is left blank and Enter is pressed, then you are in Basic.
In Basic, you can run CLOAD "PROGRAMNAME" to load software from tape.

To Load machine-code program, don't enter Basic, but just type its name, then press Enter. You'll get "start tape" prompt and program will be loaded.

Making programs on cassette:

The method for BASIC programs (in .SSS format) is similar to one from KC85/4. There is a data converter in JKCEMU emulator which can convert between SSS format and a WAV file, but you won't get proper headers as it just rips memory and encodes it to WAV. Better WAVs are generated by toolchain of KCEMU emulator. Download it freely from author's site looking for "Kassetten transfer" file ( Then select:
 - Automatische speichern - checked
 - Kodierung: KC85/1..4, KC87
 - In: as selected by program.
 - Out: Datei KCLOAD.WAV
Now click "Speichern auf Kassette..." and select SSS file. The file will be rendered to KCLOAD.WAV.

If it doesn't work either, there's a modified version of KCLOAD program downloadable here:
It can also process machine-code programs stored in COM files!

In every program, it's good to try with all converters, JKCEMU, KCEMU and KCEMU with modification. JKCEMU will show you starting addresses. To run converter in JKCEMU click Extra->Werkzeuge->Dateikonverter.


All as seen from the user side, not the opposite one:

Cassette port:

1 - Cassette OUT
2 - GND
3 - Cassette IN
4  - nc
5 - nc

RGB port:

1 - G
2 -  B
3 - SYNC
4 - R
5 - +5V
Shield - Ground

Joystick connector unknown.

Useful links (Warning: in German):

 - - Look in "Hobby" / KC87 - lots of useful documentation
 - - Nice site with tapes, documentation and information.
 - - At RobotronTechnik
 - - JKCEMU emulator
 -,_KC_85/1,_KC_87 - German Wikipedia page of Robotron KC87 with prototype photo.