{"id":34201,"date":"2025-03-21T20:00:00","date_gmt":"2025-03-21T19:00:00","guid":{"rendered":"https:\/\/www.jungsi.de\/?p=34201"},"modified":"2026-03-13T12:39:30","modified_gmt":"2026-03-13T11:39:30","slug":"kc-compact-veb-muehlhausen","status":"publish","type":"post","link":"https:\/\/www.jungsi.de\/en\/kc-compact-veb-muehlhausen\/","title":{"rendered":"KC Compact"},"content":{"rendered":"
The KC Compact \u2013 A rare treasure from the history of GDR computers<\/h5>\n\n\n\n

I never thought I would ever write a report about this computer. Due to when it was created, the KC Compact is so rare that it is hardly to be found on the usual platforms. When one does turn up, the price is often well over \u20ac1,000.<\/p>\n\n\n\n

The creation of the KC Compact<\/h5>\n\n\n\n

The KC Compact was the last home computer to be developed and produced in the GDR. It was unveiled in October 1989 on the occasion of the GDR's 40th anniversary \u2013 just a few weeks before the fall of the Berlin Wall. The big presentation at the Leipzig Spring Fair in 1990 was a flop, as hardly anyone was interested in the computer anymore. In April 1990, series production finally began, originally planned for 20,000 units. There are only estimates of the actual number of units produced \u2013 my copy bears the serial number 2534. The introductory price was 2,300 East German marks, but quickly fell to 1,000 East German marks. After the currency union, the KC Compact was finally sold off for 230 DM.<\/p>\n\n\n\n\n\n\n\n

The order to develop a Schneider CPC clone came directly from the state leadership. The engineers at VEB Mikroelektronik \u201cWolfgang Pieck\u201d M\u00fchlhausen took over both development and production \u2013 albeit with little enthusiasm, as they had previously designed all computers independently and felt it was a step backwards to implement a specified design.<\/p>\n\n\n\n

There was even a special drive and interface from VEB Mikroelektronik M\u00fchlhausen, which is even rarer to find than the KC Compact itself.<\/p>\n\n\n\n

\"KC
KC compact<\/figcaption><\/figure>\n\n\n\n
Technical details<\/h5>\n\n\n\n

The KC Compact was integrated into the housing of the 5105 educational computer. The UA 880D, a DDR clone of the Z80 with a clock frequency of 4 MHz, was used as the processor. The Motorola 6845 graphics chip was replicated in Bulgaria under the name CM 607 and supported a maximum resolution of 640 \u00d7 200 pixels with two colors. The sound chip, an AY-3-8910 clone, was produced in the GDR as the U 8912.<\/p>\n\n\n\n

For input and output, the U82536 (a Zilog 8546 clone) replaced the components specially developed by Amstrad. One difference from the Amstrad computers was the KC Compact's external power supply, which was supplemented by additional voltage regulation on the motherboard.<\/p>\n\n\n\n

The power supply unit in the original delivers 20 V DC, which is then converted in the computer via a fixed voltage regulator (B3170) to +12 V and a switching regulator (B2960) to +5 V.
When viewed from the rear, the right-hand contact (towards the tape jack) is the positive pole.
When looking at the cable coming from the power supply, the positive pole is on the left (notch is at the top).<\/p>\n\n\n\n

The serial number of my device is 2534, so it could be one of the later devices. A mixture of East German and Western chips was used.
\u2013 UA880D from the GDR \u2013 clone of the Z80 (processor)
\u2013 AY-3-8912A from GI in Taiwan (sound)
\u2013 MC6845P \u2013 original from Motorola (graphics)
\u2013 ST M27256FI from ST Microelectronics (ROM)
\u2013 U82536DC04 \u2013 from the GDR (counter\/timer and I\/O)
\u2013 KP580BB55A \u2013 clone of the Intel i8255 from Russia (I\/O)
\u2013 U2164D \u2013 from the GDR 64Kx1 bit RAM (8 KB RAM)<\/p>\n\n\n\n

\"KC
KC compact \u2013 Circuit board with labels<\/figcaption><\/figure>\n\n\n\n
Differences from the Amstrad CPC<\/h5>\n\n\n\n

Although the KC Compact was based on the Amstrad CPC, there were a few differences:<\/p>\n\n\n\n