Editing Electronika BK

{{More citations needed|date=June 2007}}
{{Infobox information appliance
| name = Electronika BK
| image = Bk0010-01-sideview.jpg
| caption = Elektronika BK0010-01
| developer = NPO Scientific Center
| manufacturer = [[Elektronika]]
| type = [[Home computer]]
| release date = {{Start date and age|1985}}
| price = 600–650 [[Soviet rouble|Rbl]]s
| discontinued = {{Start date and age|1993}}
| os = OS BK-11, [[ANDOS]]; [[FOCAL (programming language)]], [[Vilnius BASIC]] (ROM embedded), etc.
| cpu = [[1801 series CPU|K1801VM1]] @3MHz (BK-0010), @4.6MHz (BK-0011), @4MHz (BK-0011M)
| memory = 32 [[KiB]]
| marketing_target = [[Personal computer]] users
| graphics = K1801VP1-037
| display = 512×256 monochrome, 256×256 with 4 colors
| sound = Beeper
| compatibility = [[PDP-11]] compatible
}}
The '''Electronika BK''' is a series of [[16-bit computing|16-bit]] [[PDP-11]]-compatible [[home computer]]s developed under the [[Electronika]] brand by NPO Scientific Center, then the leading [[microcomputer]] design team in the [[Soviet Union]]. It is also the predecessor of the more powerful [[UKNC]] and [[DVK]] micros.

==Overview==
First released in 1985 (developed in 1983), they are based on the К1801ВМ1 (Soviet [[PDP-11#LSI-11|LSI-11]]-compatible CPU) and were the only ''official'' (government approved and accounted for in economic planning) Soviet home computer design in mass production.

They sold for about 600–650 [[Soviet rouble|roubles]]. This was costly, as the average Soviet monthly wage then was about 150 roubles. Despite their cost, they became one of the most popular home computer models in the Soviet Union. Later, in the 1990s, their powerful [[central processing unit]] (CPU) and straightforward, easy-to-program design made them popular as [[demoscene]] machines. ''BK'' (''{{lang|ru|БК}}'') is a [[Russian language|Russian]] abbreviation for {{lang|ru|"бытовой компьютер"}} (bytovoy kompyuter) – domestic (or home) computer. The machines were also used for a short time as [[cash register]]s, for example, in the [[GUM (department store)|GUM department store]].

==Software==
[[File:Basic-Vilnus.png|thumb|right|[[Vilnius BASIC]] on a BK-0010.01]]

The BK series is a bare-bones machine, with no [[peripheral]]s or [[programming tool]]s. The only [[software]] available at the launch, except [[read-only memory]] (ROM) [[firmware]], is an included magnetic tape with several programming examples (for the languages [[BASIC]] and [[FOCAL (programming language)|FOCAL]]), and several tests. The ROM firmware includes a simple program to enter machine codes, BASIC and FOCAL interpreters.

While the BK is somewhat compatible with larger and more expensive [[DVK]] professional model [[microcomputer]]s and industrial [[minicomputer]]s like the [[SM EVM]] series, its 32 KiB memory, of which only 16 KiB is generally available to programmers (an extended memory mode supports 28 KiB, but limits video output to a quarter of the screen), generally precludes direct use of software for the more powerful machines. The DVK became a popular development platform for BK software, and most DVK software can be used directly with memory capacity extended to 128&nbsp;KiB.

<!-- Deleted image removed: [[File:osbk11.png|256px|left|thumb|BK-0011M running OS BK-11, the only OS supported by the developer and Inter Commander file manager]] -->
Hobbyist developers quickly filled this niche, porting several programming tools from DVK and [[UKNC]]. This led to an explosion of homebrew software, from [[text editor]]s and [[database]]s to [[operating system]]s and [[video game]]s. Most BK owners expanded the built-in RAM to at least 64 KiB, which allows easier software porting, and as these upgrades often include [[floppy drive]] controllers, individuals creating [[disk operating system]]s became something of a competitive sport in the BK scene. Games and [[demoscene]] communities also flourished, as its poor graphics are offset by a powerful CPU.

One of the [[operating system]]s was [[ANDOS]], although officially the computer shipped with OS BK-11, a modification of [[RT-11]].

==Hardware==
The machine is based on a 16-bit single-chip [[1801 series CPU|K1801VM1]] CPU, clocked generally at 3 MHz.<ref>It is relatively easy to overclock the CPU, but slow [[dynamic random-access memory]] (DRAM) made [[overclocking]] difficult. The most popular ''turbo'' speed is 5 MHz.</ref> It is compatible with [[Digital Equipment Corporation]]'s LSI-11 line, though it lacks [[PDP-11 architecture#Optional instruction sets|Extended Instruction Set]] (EIS) and further instruction set extensions. The manufacturer also closely copied the PDP-11's internal architecture. Each model has one free card slot which is electrically, but not mechanically, compatible with [[Q-Bus]]. The first version features 32 KiB onboard DRAM, half of which is [[video memory]]. That is extended to 128 KiB in later models, with video memory extended to two 16 KiB pages.

Video output on all models is provided by the K1801VP1-037 [[Video Display Controller|VDC]], a rather spartan chip. It is a standard 600 [[gate array]], or ''uncommitted logic array'' (ULA), with a VDC program that allows for two graphic video modes, high-resolution (512×256, monochrome) and low-resolution (256×256, 4 colors), and supports hardware vertical [[scrolling]]. Later models have 16 hardwired 4-color sets selectable from 64 color [[Palette (computing)|palette]]. It does not support text modes, but simulates two via [[BIOS]] routines: 32×25 and 64×25. Some operating systems such as ANDOS have managed to output text in 80×25 mode when displaying documents imported from IBM PC, by placing characters more densely. Output is through two separate 5-pin [[DIN connector]]s for a monochrome TV or color TV/monitor. Sound on all models is initially through a simple programmable counter connected to an onboard [[Loudspeakers#Piezoelectric speakers|piezo speaker]]. The [[General Instrument AY-3-8910]] is a popular aftermarket addition.

All models also have a 16-bit universal [[parallel port]] with separate input and output buses for connecting peripherals such as [[Printer (computing)|printers]] ([[Eastern Bloc]] printers used the incompatible [[IFSP]] ({{lang|ru|ИРПР}}) interface instead of the [[IEEE 1284]] (Centronics) port, so Centronics printers need an adapter), [[Computer mouse|mouse]] or [[Covox]] [[digital-to-analog converter]]s (DACs) for sound output, and [[tape recorder]] port for data storage. Later models include a manufacturer-supplied [[floppy drive]] controller (that can be plugged into a Q-Bus slot) by default. It is available for earlier models as an aftermarket part, but homebrew ones (that also often extends 16 KiB memory of original BK) are more popular.

===Versions===
====BK-0010====
[[File:Компьютер БК0010 фото3.JPG|thumb|right|BК-0010 model]]
[[File:Bk0010-01-systemboard.jpg|thumb|right|BK0010-01 system board]]
The {{lang|ru|'''Электроника БК-0010'''}} is the first model (originally released in 1983, serial production started in 1985). It has a pseudo-[[membrane keyboard]] (an array of mechanical microswitches without keycaps, covered by flexible overlay), 32 [[KiB]] RAM, 8 KiB ROM with BIOS (chip K1801RE2-017), 8 KiB ROM with [[FOCAL (programming language)|FOCAL]] [[Interpreter (computing)|interpreter]] (K1801RE2-018), 8 KiB ROM with debugger (K1801RE2-019) and one free ROM slot, and its CPU is clocked at 3 MHz. A [[tape recorder]] is used for data storage in the factory configuration.

This model was criticized for its uncomfortable keyboard – while [[Keyboard technology#Mechanical-switch keyboard|mechanical]] in nature, lack of keycaps lead to the same unsatisfactory tactile response, that was seen as unacceptable when the machine was used in home or educational settings, although such keyboard could be easily sealed fully, so this version found wide use as an [[Industrial PC|industrial controller]]. Other points of criticism included the FOCAL programming language supplied by default instead of the more common BASIC and the lack of peripherals and software. While all hardware was well-documented and easy to work with, the machine was delivered with no programming tools.

====BK-0010.01====
The follow-up version, '''БК-0010.01''' (sometimes referred to as -0010-01), is essentially the same machine, but with a conventional full-travel keyboard and a [[Vilnius BASIC]] [[p-code machine|p-code]] [[compiler]] in the ROM, correcting the weakest points of its predecessor. While the BASIC dialect used is powerful and well-optimized (it is a scaled-down clone of [[MSX BASIC]]), the keyboard still has shortcomings. While it is much more comfortable to work with, the keys were prone to sticking, significant [[Switch#Contact bounce|bounce]] and wore quickly, though a model with a further improved keyboard became available later. The FOCAL interpreter was not dropped but instead shipped on an external [[ROM cartridge]] that can be inserted into the Q-Bus slot.

====BK-0010Sh====
{{lang|ru|'''Электроника БК-0010Ш'''}} is a model intended for school use. It can be either the −0010 or −0010.01 model but includes a special [[current loop]] network adapter rated at 19200 [[bits per second]] (bit/s), which can be inserted into the [[Q-Bus]] slot. Based on ULA chip K1801VP1-035 (and later on K1801VP1-065), the adapter is compatible with [[Digital Equipment Corporation]] (DEC) DL-11 and KL-11 serial interfaces, but without modem control bits. It also includes a monitor, usually a modified Yunost' compact TV for school settings.

====BK-0011====
'''BK-0011''' was released in 1989. It has 128 KiB of RAM divided into 16 KiB pages; its CPU is clocked at 4 MHz by default. It includes a newer version of BASIC in ROM and 16 selectable video palettes, which were almost universally criticized by users for their odd color combinations. It has a floppy controller, with the drive available as an add-on.

====BK-0011M====
[[File:БК0010М белый корпус.JPG|thumb|The BK0011M white case]]
[[File:Bk0011m.jpg|thumb|The BK0011M black case]]
Some changes in the BK-0011, while minor, made it incompatible with earlier -0010 models. It cannot load 0010 programs from a cassette tape. Even if it could have loaded them, crucial subsystems, such as sound, are still incompatible. The manufacturer redesigned the machine, restoring compatibility with earlier models. The resulting model, the BK-0011M, quickly went into production, and most BK-0011 series computers are actually BK-0011Ms. Since the modifications were minor, most of the handful of -0011 models that made it to market have been upgraded to -0011M models by enthusiasts.

===Mods===
It is not uncommon among owners to install one or two mechanical [[switch]]es that made using the computer more convenient. Some of the common mods were:

* '''[[Reset (computing)|Reset]] [[push-button]]'''. [[Computer program|Programs]] often [[Hang (computing)|hang]]. Also, some [[Video game|games]] do not have a properly implemented Exit function. Without this button, the computer has to be reset by [[power cycling]], which eventually leads to a worn out power switch on the external power supply. The reset interrupt can be caught by the operating system, so under such systems (for example, [[ANDOS]], [[MK-DOS]]), the reset button exits to the OS's [[file manager]].
* '''Pause switch'''. This switch activates hardware suspension of [[Computer program#Program execution|instruction execution]] in the processor. The pause switch is useful for pausing games, most of which do not have a [[Break key|pause key]]. A few games, however, do not behave gracefully after being returned from suspension, because the programmable hardware [[Timer#Computer timers|timer]] built into the processor [[Integrated circuit|chip]] is still running while the instruction execution was suspended. The BK also has a software key combination for pause.
* '''Clock speed switch''' (''turbo'' switch). This changes the processor [[Clock rate|clock speed]] from the standard 3 MHz (BK-0010* series) to 4 or 6 MHz, or from the standard 4 MHz (BK-0011* series) to 3 or 6 MHz. Not all processor samples work reliably at 6 MHz; the possibility of such [[overclocking]] has to be determined experimentally for each sample. Switching the clock speed changes the pace of dynamic games. The turbo switch usually has to be installed together with the pause switch, because the simplest circuit for switching the clock speed produces bad [[waveform]] shapes in the clock signal due to [[Switch#Contact bounce|contact bounce]] in the mechanical switch, running the risk of hanging the software execution unless the processor is in the suspended state.
* '''Sound on/off switch''', or '''sound volume knob''', which adjusts the [[Loudness|volume level]] of the internal [[Loudspeakers#Piezoelectric speakers|piezoelectric speaker]] using a [[potentiometer]]. At this same time as adding this, the modder can replace the speaker with a louder one.

Enthusiasts also manage to connect more advanced devices to BK series computers: they developed a [[hard disk drive]] (HDD) controller, and 2.5" HDDs have been successfully used with BK computers. Other popular enhancements are [[General Instrument AY-3-8910|AY-3-8912]] sound chips and [[Covox Speech Thing]].

==Emulators==
There are various software [[emulator]]s of BK for modern [[IBM PC compatible]] computers. An emulator is able to run at a much higher speed than the original BK.

There are also fairly complete re-implementations of the BK for [[field-programmable gate array]] (FPGA) based systems, such as the MiST.<ref>{{cite web |url=https://github.com/sorgelig/BK0011M |title=BK0011M (USSR retro home computer) core for MiST board |website=[[GitHub]] |date=2016-03-29 |access-date=2016-04-16}}</ref>

==See also==
* [[Heathkit H11]]

==References==
{{Reflist}}

==External links==
* [http://www.bk001x.ru Electronika BK0010(-01) & BK0011(M)] USSR PC [PDP-11]
* [http://aminet.net/package/misc/emu/bkemul16 BK0010 Russian computer emul.] v1.6 w/src
* [http://archive.pdp-11.org.ru/ Archive software and documentation for Soviet computers UK-NC, DVK and BK0010.]

{{List of Soviet computer systems}}
{{Operating systems for Elektronika BK}}

{{DEFAULTSORT:Electronika Bk}}
[[Category:Home computers]]
[[Category:PDP-11]]
[[Category:Ministry of the Electronics Industry (Soviet Union) computers]]
[[Category:Computer-related introductions in 1985]]