15 декабря 2015

                    ZX Spectrum in GDR (DDR)
                            by utz

Although being far ahead of the West in the early days of the
computer age, by the 1980s the situation in the GDR looked as
grim as just about anywhere in the Eastern block. Official
GDR-produced computers were mostly unavailable to the public,
western computers had to be either illegally imported or (after
1985) bought for "hard" currency and at horrendous prices at the
"Intershop", and although there were many hobbyist computer
designs published in various magazines and books from 1984
onwards, few of them were actually built due to the
unavailability of the necessary components.

Nevertheless, there were several Spectrum clones made, though
none of them was produced in any significant quantities.

The first GDR clone, called GDC1 (Grafik-Display-Computer 1),
was developed at the TH Ilmenau (Technical University Ilmenau)
in 1985. Like all GDR ZX clones, it uses the home-made U880 CPU
in place of a Z80. It's compatibility is rather limited: The CPU
pauses during screen redraw, IO is controlled via a PIO rather
than IO ports, and of course no ULA (replaced by 2 domestically
made PIOs (U855) and a CTC (U857)). Also, the ROM consist of
just a ЧKB EPROM bootloader, which loads the actual OS from
tape. The machine had 64K RAM in the standard configuration and
could be extended to 256K. There were several versions of this
machine, all with a similar configuration. It is not known how
many boards were produced, and only very few survive today. The
nickname "FDJ-Computer" suggests that it was endorsed by the FDJ
(Free German Youth, the state-run youth organization) in some
places. http://www.robotron-net.de/eigenbau.html#GDC

Next, we had Spectral, also known as EPRO2. It was developed by
IFAM (Engineer Office for Applied Microelectronics) Erfurt in
1987, build by VEB Mikroelektronik "Karl Marx", and sold by VEB
Robotron-Vertrieb Erfurt from December 1988 on. Latter company
still exists today under the name "Hubner-Elektronik", as well
as the IFAM, which still holds the rights to the design. The
machine had 48K of RAM (extendable to 128K) and supposedly had a
very high level of compatibility with the original Spectrum,
unlike most other GDR clones. As a bonus, it sported a joystick
port. http://www.sax.de/~zander/zx/spectral.html
http://www.robotron-net.de/eigenbau.html#Spectral A project was
done to rebuild the Spectral some years ago:
http://www.sax.de/~zander/zx/spec_nb.html

Also in 1987/88, the HCX was developed by the Technical
University and the Schwermaschinenbau-Kombinat "Ernst Thalmann"
in Magdeburg (SKET, Heavy Machinery Combinate). It had only
limited compatibility (ULA simulated by U885 and U887 standard
ICs, modified ROM), but sported two joystick ports. The HCX was
supposed to be mass-produced, but never made it into serial
production. 30 boards were produced by VEB GALVANO in
Wernigerode in 1989, and assembled into full machines by a local
computer hobbyist club in Magdeburg. No working machines are
known to have survived.
http://www.sax.de/~zander/zx/hcx.html
http://www.robotron-net.de/eigenbau.html#HCX

Near the very end of the GDR, the AdW - ZKI (Academy of Science
of the GDR, Central Institute for Cybernetics and Information
Processing) in Berlin, released the KuBбЧ, which was sold in kit
form by the ZWG (Center for Scientific Machine Construction) in
Liebenwalde. Like the GDC, it contained only a 1K or 2K
bootloader EPROM to load the OS from tape, but otherwise it is
said to have been very compatible with the original Spectrum.
Also, there were designs for extending the ROM to 16K and thus
integrating the ROM into the machine. It had a built-in floppy
disk controller (U8272, a clone of NEC pd765/Intel 8272), and
thus could run CP/M. Also, it could be connected to a Robotron
K7222 system monitor as well as the usual RF. Only 4 machines
are known to have survived to the present day.
http://www.sax.de/~zander/zx/kubбЧ.html

 Another ZX clone was developed at the
Halbleiterwerk-Frankfurt/Oder (Semiconductor Plant
Frankfurt/Oder). Little is known about this machine, but two
surviving boards have been restored to working order.
http://www.sax.de/~zander/zx/hfo.html

 Some even more obscure hobbyist clones exist. The only one that
is at least documented to some extent is the "ZX-Jena"
(http://www.sax.de/~zander/zx/zxj.html). Another self-made
design was the BCS 03
(http://www.robotron-net.de/eigenbau.html#BCS). Only a few
photos still exist of the latter, though rumour has it that the
design was published in a magazine somewhere.

 Further info:
http://www.robotrontechnik.de/html/computer/bausaetze.htm

                             * * *

> Wow! I haven't heard about these clones before! Interesting 
> thing is loading "ROM" data from tape, I knew this in 
> ATM Turbo only, as an option 
> (it was mentioned in documentation, I don't know actual 
> computers made this way). 

Seems it was rather common in GDR, other (non-Spectrum
compatibles) did this as well. Probably for reasons of the usual
economic mismanagement, they had enough RAM but a shortage of
larger ROM chips. Or perhaps a lack of suitable EPROM burners.
But I can only speculate about this.

utz