Orel BK-08 (Орель БК-08)

Orel (Russian Орель - Eagle) is a ZX-Spectrum clone designed in late 80s. It was manufactured in Dnepropetrovsk Machine building plant in Ukraine until 1993 or 1994, but sold also in 1995. Later units have sticker "UkrSertRea" (укрсертрэа) Which was seller name after Soviet Union split. Because in 1990s in post-Soviet countries any computer was valuable (if it was not working - as source of precious metals), some individual customers, culture centres and schools purchased this outdated computer to teach Basic language.
Orel is a Z80-powered ZX Spectrum clone with 64kB of RAM. It is made using TTL logic chips and 3 PROM circuits to form signals. This "emulation" made it quite compatible with ZX Spectrum. It was described as "Video game computer" or "Home computer", in some abbreviations "BU" - Bytoveje Ustrojstvo - Home-use device.
This computer outputs graphics in RGB+Sync system. In manual it can be read how to connect these signals to most soviet TV Sets of these times. It can be connected to SCART too, but signals are quite weak and picture is dark.
Orel's version 01 had also joysticks in set. Orel can work with 2 joysticks through unknown DIN sockets.
The computer is equipped with 60-minute cassette tape, which contains about 8 minutes of program: Demonstration program "Reklama", testing software "tst" and MZ80 monitor. Contrary to ZX Spectrum, Orel has both Reset and NMI signals user-controlled by switches.
As with most Soviet hardware, instruction contains technical description and schematic. And as most Soviet computers, Orel was manufactured in quite small amount because there were problems with parts availability.
Inside, the only chip which is not Soviet is CPU, which is Korean (Goldstar), some early units have East German CPU (MME Z80A). During servicing it should be noted that soviet ICs in plastic casings are poor in quality and may become damaged even by temperature difference in short time.
An interesting feature of Orel was its "shadow RAM". It was possible to load some program to special place in RAM, set it and reinitialize computer. Then Orel starts executing the code form this place in RAM as it was from ROM. This operation allows to develop own ROM replacements. Orel's design allows to install 2 sets of 2x8kB ROM chips, but by default only one is used.

Orel's keyboard is magnetic reed-based. This technology popular in Eastern block countrier allows to build modular and reliable keyboards but is expensive as each key requires its own reed switch and magnet. Keyboard is more ergonomic than in ZX Spectrum, has arrows in a normal shape and control keys clearly divided from alphanumeric ones.

Manufacturer Dnepropetrovsk Machine Building Plant

Origin USSR / Ukraine
Year of unit 1994/95
Year of introduction 1980s?
End of production 1995
Speed 3.5MHz
ROM 16kB
Colors: 16
Sound: Beeper
Display modes: Text: 32x24
Graphics: 256x192


Media: Tape recorder  

Power supply:

DC connector

1 - +24V DC 400mA
2 - Ground

I/O: Tape in, Tape out
RGB out
Z80 bus
2x joystick
Possible upgrades: None known

Software accessibility: Spectrum software  

My unit is in a very good condition. It is new, but one chip failed so I had to rpelace it. In a set I have original power supply (24V 400mA), cables, manuals and cassette.

Orel demonstration program (see fileland). This screenshot has been obtained from RGB, the only card which could capture color from Orel was old ISA-based framegrabber marked "CL".

Contents: Starting Recording tapes Pinouts Links


It boots just to BASIC. BASIC's messages are translated to Russian, so you'll get something like:

Бейсик - Система Вер. 2.0

This means "BASIC System v. 2.0"
Next, you can load programs as ZX Spectrum software.

To load MZ80 monitor: Use  LOAD "" CODE (J, then ", then ", then Ctrl-J), Return, start tape, After loading press NMI button.

Recording tapes:

See ZX Spectrum






1 - Sound
2 - Sync
3 - Blue
4 - Green
5 - Red
6 - GND
7 - +12V DC.

Connecting to SCART (Orel->SCART):
1 -> 2+6
2 -> 20
3 -> 7
4 -> 11
5 -> 15
6 -> 18+17+13+5+4+9
7 -> 470R -> 16
Not all TV-sets will get proper picture, it may be very dark.

Cassette IN:

2 - GND
3 - Input

Cassette OUT:

2 - GND
3+ 5 - Output.





http://speccy.info/%D0%9E%D1%80%D0%B5%D0%BB%D1%8C-%D0%91%D0%9A08  - Info about Orel [RUSSIAN], schematics and manuals for download. Better scans than my.
http://oldmachinery.blogspot.com/2013/11/orel-bk-08.html - Another Orel info page. Probably contains information hot to properly connect Orel RGB to SCART.
http://www.computinghistory.org.uk/det/29848/OREL-BK-08-Russian-Spectrum/ - Contains automatic translation of now-defunct Ukrainian page about Orel.
https://sites.google.com/site/bigralsbay/home/orel-bk-08-zx-spectrum-clone - Interesting downloads and (in Russian) schematic analysis in PDF.