KC compact

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KC compact
KC-compact-1.jpg
Manufacturer Germany Democratic Republic 1949GDR VEB microelectronics "Wilhelm Pieck" Mühlhausen
Type Home computers
publication probably October 7, 1989
End of production probably after July 5, 1990
Factory price unknown
processor U880D or Zilog Z80
@ 4.0 MHz
random access memory 64 KB
graphic Motorola 6845
Sound General Instrument AY-3-8912
Disk 5.25 ″ diskette , plug-in modules , audio cassettes ( Datasette )
operating system MicroDOS or CP / M 2.2

The KC compact was the last 8-bit small computer ( home computer ) with 4 MHz and 64  KB RAM built in the GDR . The computer is a replica of the Amstrad / Schneider CPC and comes from the VEB Microelectronics "Wilhelm Pieck" Mühlhausen . The KC compact was not ready for series production until the end of the GDR (ironically as a gift for the 40th birthday of the republic), so only a few devices were produced and sold.

Computer replicas in the Eastern Bloc

In times of the Cold War and the associated trade restrictions, it was quite common in the Eastern Bloc to obtain microelectronics and even entire computers by any means in the West and to analyze them using the reverse engineering method . The devices were then rebuilt using the resources available in the east. In this way, gaps in demand could be closed relatively easily, and specialists were trained. A good and well-known example are the numerous spectrum clones of the Eastern Bloc, but also IBM- compatible mainframes , especially the uniform system of electronic computing technology , have appeared beyond the “iron curtain” .

In the accompanying service manual, components from abroad are always marked as such, e.g. B. AY-3-8912 (import NSW ) , SM 607 (import Bulgaria) etc.

hardware

Manuals for hardware and software for the KC compact

The computer consists of a basic device with an external power supply unit. The same housing was used as for the Robotron BIC A 5105 , but the electronics cannot be exchanged. The following connections are available on the KC:

  1. Power supply from the power supply
  2. SCART socket for connection to the television (good picture and sound quality)
  3. Antenna output for connection to the television (poor picture and sound quality)
  4. Diode socket to the cassette recorder (external mass storage)
  5. Diode socket as an additional audio output
  6. Expansion port for additional devices such as a floppy disk drive
  7. Printer port

Because of the built-in power supply for external devices, care should be taken when connecting original CPC parts.

A UA880 CPU based on the U880 works in the computer . 16 KB of the 64 KB RAM are used as the image refresh memory by default . This means that with 640 × 200 points 2, with 320 × 200 points 4 and with 160 × 200 points 16 out of 27 colors. As with the CPC, the screen control is implemented via an unconventionally connected Motorola 6845 ; therefore the size and position of the image and the image refresh memory are very largely programmable. The sound (AY-3-8912 sound chip) could still be classified as good at the beginning of the 90s and went well beyond the beeping noises of the KC-85 series. Envelopes as well as noise can be generated. The CIO circuit U82536 / U8036 (or Zilog Z8536) fulfills the functions of PIO and CTC. Some special circuits of the Western model were replaced by logic gates, a method common in the GDR.

A floppy disk drive was also developed as an additional device. This means that the KC compact is in principle CP / M compatible.

The introductory price was 2,300 marks, which was quickly reduced to 990 marks.

The number of pieces can currently be estimated at at least 2440.

software

Program cartridges for the KC compact, mostly games

After switching on, the BASIC interpreter is started and you can immediately start writing programs. The BASIC 1.1 is very comfortable (because the locomotive BASIC 1.1 of the CPC was simply copied). Because of the software compatibility with western CPCs, you can fall back on a wide range of games and applications. Some games and applications such as word processing , graphics programs and Pascal as a programming language came from the manufacturer .

The KC compact and its technology

With 64 KB RAM and BASIC 1.1, this " CPC computer " could be classified between CPC 6128 and CPC 664 . Instead of CP / M as the operating system, a Germanized CP / M 2.2 clone called MicroDOS was used, which was previously in use on various DDR computers. So software was probably available.

Externally in the square, flat, bright housing without a drive, more similar to the C64 than the CPCs, a replica of the well-known computer technology with other means was hidden under the keyboard. Among other things, was used:

  • as CPU a U880 (or UA 880D), a Z80 clone
  • a programmable "Zilog 8546" I / O module type U82536 instead of the special Amstrad modules. Theoretically, 64 colors or further assembler I / O optimizations were possible.
  • further standard modules from production in the GDR, USSR and other Eastern Bloc countries
  • ROM content adapted to the changed hardware

Externally it can be determined:

  • standardized interfaces ( DIN , Centronics interface, etc.)
  • an external power supply with further voltage reduction on board
  • serves as a storage medium - in contrast to the special datasettes , such as B. used with the Commodore C64 - a commercially available cassette drive or an external 5¼ "floppy disk drive, which is connected via an external controller, which is attached as a" backpack "on the CPC 464. In this case, the KC compact contained an additional 64 KB of RAM so that a KC compact equipped in this way largely corresponded to the Amstrad / Schneider CPC6128.
  • a versus the original CPC extended power supply for the external peripherals via the standard interfaces.
  • a (direct) connection option for a screen or television

The replica is so successful that the compatibility of the somewhat different computer can even be assessed within the CPC computer series. The hardware interfaces are only partially identical, however, and individual calls also differ, as different peripherals were connected. It is questionable whether the I / O performance increases possibly possible with the changed chipset hardware have ever been used.

With two computers connected by cable, it was possible, unique within the CPC series, to clone the memory content on the other computer. This should have been primarily intended for program development and the necessary test runs.

The production time between October 7, 1989 (GDR anniversary) and 1990 (reunification) is unconfirmed. Not much is known about the distribution, number of items or use of the computer within the GDR. The floppy disk drive was still available until July 5, 1990 for 300.00 DM. Due to the short production time and the associated low number of items, functional KC compacts have a high collector's value that considerably exceeds that of its western brothers.

See also

Web links

for further reading

Individual evidence

  1. ↑ Service instructions for the small computer KC compact , ed. VEB Microelectronics "Wilhelm Pieck" Mühlhausen, February 1990, p. 26 ff.
  2. ↑ http://mpm-kc85.de/bild/bestellschein_900705_01.JPG