<s>
The	O
Electronika	B-Device
BK	I-Device
is	O
a	O
series	O
of	O
16-bit	B-Device
PDP-11-compatible	O
home	O
computers	O
developed	O
under	O
the	O
Electronika	O
brand	O
by	O
NPO	O
Scientific	O
Center	O
,	O
then	O
the	O
leading	O
microcomputer	B-Architecture
design	O
team	O
in	O
the	O
Soviet	O
Union	O
.	O
</s>
<s>
It	O
is	O
also	O
the	O
predecessor	O
of	O
the	O
more	O
powerful	O
UKNC	B-Device
and	O
DVK	B-Device
micros	O
.	O
</s>
<s>
Later	O
,	O
in	O
the	O
1990s	O
,	O
their	O
powerful	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
and	O
straightforward	O
,	O
easy-to-program	O
design	O
made	O
them	O
popular	O
as	O
demoscene	O
machines	O
.	O
</s>
<s>
The	O
BK	O
series	O
is	O
a	O
bare-bones	O
machine	O
,	O
with	O
no	O
peripherals	O
or	O
programming	B-Application
tools	I-Application
.	O
</s>
<s>
The	O
only	O
software	O
available	O
at	O
the	O
launch	O
,	O
except	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
)	O
firmware	B-Application
,	O
is	O
an	O
included	O
magnetic	O
tape	O
with	O
several	O
programming	O
examples	O
(	O
for	O
the	O
languages	O
BASIC	O
and	O
FOCAL	B-Language
)	O
,	O
and	O
several	O
tests	O
.	O
</s>
<s>
The	O
ROM	B-Device
firmware	B-Application
includes	O
a	O
simple	O
program	O
to	O
enter	O
machine	O
codes	O
,	O
BASIC	O
and	O
FOCAL	B-Language
interpreters	B-Application
.	O
</s>
<s>
While	O
the	O
BK	O
is	O
somewhat	O
compatible	O
with	O
larger	O
and	O
more	O
expensive	O
DVK	B-Device
professional	O
model	O
microcomputers	B-Architecture
and	O
industrial	O
minicomputers	B-Architecture
like	O
the	O
SM	B-Device
EVM	I-Device
series	O
,	O
its	O
32KiB	O
memory	O
,	O
of	O
which	O
only	O
16KiB	O
is	O
generally	O
available	O
to	O
programmers	O
(	O
an	O
extended	O
memory	O
mode	O
supports	O
28KiB	O
,	O
but	O
limits	O
video	O
output	O
to	O
a	O
quarter	O
of	O
the	O
screen	O
)	O
,	O
generally	O
precludes	O
direct	O
use	O
of	O
software	O
for	O
the	O
more	O
powerful	O
machines	O
.	O
</s>
<s>
The	O
DVK	B-Device
became	O
a	O
popular	O
development	O
platform	O
for	O
BK	O
software	O
,	O
and	O
most	O
DVK	B-Device
software	O
can	O
be	O
used	O
directly	O
with	O
memory	O
capacity	O
extended	O
to	O
128KiB	O
.	O
</s>
<s>
Hobbyist	O
developers	O
quickly	O
filled	O
this	O
niche	O
,	O
porting	O
several	O
programming	B-Application
tools	I-Application
from	O
DVK	B-Device
and	O
UKNC	B-Device
.	O
</s>
<s>
This	O
led	O
to	O
an	O
explosion	O
of	O
homebrew	O
software	O
,	O
from	O
text	B-Application
editors	I-Application
and	O
databases	O
to	O
operating	B-General_Concept
systems	I-General_Concept
and	O
video	O
games	O
.	O
</s>
<s>
Most	O
BK	O
owners	O
expanded	O
the	O
built-in	O
RAM	O
to	O
at	O
least	O
64KiB	O
,	O
which	O
allows	O
easier	O
software	O
porting	O
,	O
and	O
as	O
these	O
upgrades	O
often	O
include	O
floppy	B-Device
drive	I-Device
controllers	O
,	O
individuals	O
creating	O
disk	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
became	O
something	O
of	O
a	O
competitive	O
sport	O
in	O
the	O
BK	O
scene	O
.	O
</s>
<s>
One	O
of	O
the	O
operating	B-General_Concept
systems	I-General_Concept
was	O
ANDOS	B-Device
,	O
although	O
officially	O
the	O
computer	O
shipped	O
with	O
OS	O
BK-11	O
,	O
a	O
modification	O
of	O
RT-11	B-Operating_System
.	O
</s>
<s>
The	O
machine	O
is	O
based	O
on	O
a	O
16-bit	B-Device
single-chip	O
K1801VM1	B-General_Concept
CPU	O
,	O
clocked	O
generally	O
at	O
3MHz	O
.	O
</s>
<s>
The	O
manufacturer	O
also	O
closely	O
copied	O
the	O
PDP-11	B-Device
'	O
s	O
internal	O
architecture	O
.	O
</s>
<s>
Each	O
model	O
has	O
one	O
free	O
card	O
slot	O
which	O
is	O
electrically	O
,	O
but	O
not	O
mechanically	O
,	O
compatible	O
with	O
Q-Bus	B-Architecture
.	O
</s>
<s>
Video	O
output	O
on	O
all	O
models	O
is	O
provided	O
by	O
the	O
K1801VP1-037	O
VDC	B-General_Concept
,	O
a	O
rather	O
spartan	O
chip	O
.	O
</s>
<s>
It	O
is	O
a	O
standard	O
600	O
gate	O
array	O
,	O
or	O
uncommitted	O
logic	O
array	O
(	O
ULA	O
)	O
,	O
with	O
a	O
VDC	B-General_Concept
program	O
that	O
allows	O
for	O
two	O
graphic	O
video	O
modes	O
,	O
high-resolution	O
(	O
512×256	O
,	O
monochrome	O
)	O
and	O
low-resolution	O
(	O
256×256	O
,	O
4	O
colors	O
)	O
,	O
and	O
supports	O
hardware	O
vertical	O
scrolling	O
.	O
</s>
<s>
Later	O
models	O
have	O
16	O
hardwired	O
4-color	O
sets	O
selectable	O
from	O
64	O
color	O
palette	B-Data_Structure
.	O
</s>
<s>
It	O
does	O
not	O
support	O
text	O
modes	O
,	O
but	O
simulates	O
two	O
via	O
BIOS	B-Operating_System
routines	O
:	O
32×25	O
and	O
64×25	O
.	O
</s>
<s>
Some	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
ANDOS	B-Device
have	O
managed	O
to	O
output	O
text	O
in	O
80×25	O
mode	O
when	O
displaying	O
documents	O
imported	O
from	O
IBM	O
PC	O
,	O
by	O
placing	O
characters	O
more	O
densely	O
.	O
</s>
<s>
Output	O
is	O
through	O
two	O
separate	O
5-pin	O
DIN	B-Architecture
connectors	I-Architecture
for	O
a	O
monochrome	O
TV	O
or	O
color	O
TV/monitor	O
.	O
</s>
<s>
The	O
General	B-Device
Instrument	I-Device
AY-3-8910	I-Device
is	O
a	O
popular	O
aftermarket	O
addition	O
.	O
</s>
<s>
All	O
models	O
also	O
have	O
a	O
16-bit	B-Device
universal	O
parallel	B-Device
port	I-Device
with	O
separate	O
input	O
and	O
output	O
buses	O
for	O
connecting	O
peripherals	O
such	O
as	O
printers	O
(	O
Eastern	O
Bloc	O
printers	O
used	O
the	O
incompatible	O
IFSP	B-Architecture
(	O
)	O
interface	O
instead	O
of	O
the	O
IEEE	B-Device
1284	I-Device
(	O
Centronics	O
)	O
port	O
,	O
so	O
Centronics	O
printers	O
need	O
an	O
adapter	O
)	O
,	O
mouse	B-Device
or	O
Covox	O
digital-to-analog	O
converters	O
(	O
DACs	O
)	O
for	O
sound	O
output	O
,	O
and	O
tape	O
recorder	O
port	O
for	O
data	O
storage	O
.	O
</s>
<s>
Later	O
models	O
include	O
a	O
manufacturer-supplied	O
floppy	B-Device
drive	I-Device
controller	O
(	O
that	O
can	O
be	O
plugged	O
into	O
a	O
Q-Bus	B-Architecture
slot	O
)	O
by	O
default	O
.	O
</s>
<s>
It	O
has	O
a	O
pseudo-membrane	O
keyboard	O
(	O
an	O
array	O
of	O
mechanical	O
microswitches	O
without	O
keycaps	O
,	O
covered	O
by	O
flexible	O
overlay	O
)	O
,	O
32KiB	O
RAM	O
,	O
8KiB	O
ROM	B-Device
with	O
BIOS	B-Operating_System
(	O
chip	O
K1801RE2-017	O
)	O
,	O
8KiB	O
ROM	B-Device
with	O
FOCAL	B-Language
interpreter	B-Application
(	O
K1801RE2-018	O
)	O
,	O
8KiB	O
ROM	B-Device
with	O
debugger	O
(	O
K1801RE2-019	O
)	O
and	O
one	O
free	O
ROM	B-Device
slot	O
,	O
and	O
its	O
CPU	O
is	O
clocked	O
at	O
3MHz	O
.	O
</s>
<s>
This	O
model	O
was	O
criticized	O
for	O
its	O
uncomfortable	O
keyboard	O
–	O
while	O
mechanical	O
in	O
nature	O
,	O
lack	O
of	O
keycaps	O
lead	O
to	O
the	O
same	O
unsatisfactory	O
tactile	O
response	O
,	O
that	O
was	O
seen	O
as	O
unacceptable	O
when	O
the	O
machine	O
was	O
used	O
in	O
home	O
or	O
educational	O
settings	O
,	O
although	O
such	O
keyboard	O
could	O
be	O
easily	O
sealed	O
fully	O
,	O
so	O
this	O
version	O
found	O
wide	O
use	O
as	O
an	O
industrial	B-Device
controller	I-Device
.	O
</s>
<s>
Other	O
points	O
of	O
criticism	O
included	O
the	O
archaic	O
FOCAL	B-Language
programming	I-Language
language	I-Language
supplied	O
by	O
default	O
and	O
the	O
lack	O
of	O
peripherals	O
and	O
software	O
.	O
</s>
<s>
While	O
all	O
hardware	O
was	O
well-documented	O
and	O
easy	O
to	O
work	O
with	O
,	O
the	O
machine	O
was	O
delivered	O
with	O
no	O
programming	B-Application
tools	I-Application
.	O
</s>
<s>
The	O
follow-up	O
version	O
,	O
БК-0010.01	O
(	O
sometimes	O
referred	O
to	O
as	O
-0010-01	O
)	O
,	O
is	O
essentially	O
the	O
same	O
machine	O
,	O
but	O
with	O
a	O
conventional	O
full-travel	O
keyboard	O
and	O
a	O
Vilnius	B-Language
BASIC	I-Language
p-code	B-Language
compiler	B-Language
in	O
the	O
ROM	B-Device
,	O
correcting	O
the	O
weakest	O
points	O
of	O
its	O
predecessor	O
.	O
</s>
<s>
While	O
the	O
BASIC	O
dialect	O
used	O
is	O
powerful	O
and	O
well-optimized	O
(	O
it	O
is	O
a	O
scaled-down	O
clone	O
of	O
MSX	B-Language
BASIC	I-Language
)	O
,	O
the	O
keyboard	O
still	O
has	O
shortcomings	O
.	O
</s>
<s>
The	O
FOCAL	B-Language
interpreter	B-Application
was	O
not	O
dropped	O
but	O
instead	O
shipped	O
on	O
an	O
external	O
ROM	B-Device
cartridge	O
that	O
can	O
be	O
inserted	O
into	O
the	O
Q-Bus	B-Architecture
slot	O
.	O
</s>
<s>
It	O
can	O
be	O
either	O
the	O
−0010	O
or	O
−	O
0010.01	O
model	O
but	O
includes	O
a	O
special	O
current	O
loop	O
network	O
adapter	O
rated	O
at	O
19200	O
bits	O
per	O
second	O
(	O
bps	O
)	O
,	O
which	O
can	O
be	O
inserted	O
into	O
the	O
Q-Bus	B-Architecture
slot	O
.	O
</s>
<s>
It	O
includes	O
a	O
newer	O
version	O
of	O
BASIC	O
in	O
ROM	B-Device
and	O
16	O
selectable	O
video	O
palettes	B-Data_Structure
,	O
which	O
were	O
almost	O
universally	O
criticized	O
by	O
users	O
for	O
their	O
odd	O
color	O
combinations	O
.	O
</s>
<s>
It	O
has	O
a	O
floppy	B-Device
controller	O
,	O
with	O
the	O
drive	O
available	O
as	O
an	O
add-on	O
.	O
</s>
<s>
It	O
cannot	O
load	O
0010	O
programs	B-Application
from	O
a	O
cassette	O
tape	O
.	O
</s>
<s>
Reset	B-General_Concept
push-button	O
.	O
</s>
<s>
Programs	B-Application
often	O
hang	B-General_Concept
.	O
</s>
<s>
Without	O
this	O
button	O
,	O
the	O
computer	O
has	O
to	O
be	O
reset	B-General_Concept
by	O
power	O
cycling	O
,	O
which	O
eventually	O
leads	O
to	O
a	O
worn	O
out	O
power	O
switch	O
on	O
the	O
external	O
power	O
supply	O
.	O
</s>
<s>
The	O
reset	B-General_Concept
interrupt	O
can	O
be	O
caught	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
so	O
under	O
such	O
systems	O
(	O
for	O
example	O
,	O
ANDOS	B-Device
,	O
MK-DOS	B-Device
)	O
,	O
the	O
reset	B-General_Concept
button	O
exits	O
to	O
the	O
OS	O
's	O
file	O
manager	O
.	O
</s>
<s>
The	O
pause	O
switch	O
is	O
useful	O
for	O
pausing	O
games	O
,	O
most	O
of	O
which	O
do	O
not	O
have	O
a	O
pause	B-Device
key	I-Device
.	O
</s>
<s>
This	O
changes	O
the	O
processor	O
clock	O
speed	O
from	O
the	O
standard	O
3MHz	O
(	O
BK-0010*	O
series	O
)	O
to	O
4	O
or	O
6MHz	O
,	O
or	O
from	O
the	O
standard	O
4MHz	O
(	O
BK-0011*	O
series	O
)	O
to	O
3	O
or	O
6MHz	O
.	O
</s>
<s>
Not	O
all	O
processor	O
samples	O
work	O
reliably	O
at	O
6MHz	O
;	O
the	O
possibility	O
of	O
such	O
overclocking	B-Application
has	O
to	O
be	O
determined	O
experimentally	O
for	O
each	O
sample	O
.	O
</s>
<s>
Sound	O
on/off	O
switch	O
,	O
or	O
sound	O
volume	O
knob	O
,	O
which	O
adjusts	O
the	O
volume	B-Algorithm
level	I-Algorithm
of	O
the	O
internal	O
piezoelectric	O
speaker	O
using	O
a	O
potentiometer	B-Device
.	O
</s>
<s>
Enthusiasts	O
also	O
manage	O
to	O
connect	O
more	O
advanced	O
devices	O
to	O
BK	O
series	O
computers	O
:	O
they	O
developed	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
(	O
HDD	O
)	O
controller	O
,	O
and	O
2.5	O
"	O
HDDs	O
have	O
been	O
successfully	O
used	O
with	O
BK	O
computers	O
.	O
</s>
<s>
Other	O
popular	O
enhancements	O
are	O
AY-3-8912	B-Device
sound	O
chips	O
and	O
Covox	O
Speech	O
Thing	O
.	O
</s>
<s>
There	O
are	O
various	O
software	B-Application
emulators	I-Application
of	O
BK	O
for	O
modern	O
IBM	O
PC	O
compatible	O
computers	O
.	O
</s>
<s>
An	O
emulator	B-Application
is	O
able	O
to	O
run	O
at	O
a	O
much	O
higher	O
speed	O
than	O
the	O
original	O
BK	O
.	O
</s>
<s>
There	O
are	O
also	O
fairly	O
complete	O
re-implementations	O
of	O
the	O
BK	O
for	O
field-programmable	B-Architecture
gate	I-Architecture
array	I-Architecture
(	O
FPGA	B-Architecture
)	O
based	O
systems	O
,	O
such	O
as	O
the	O
MiST	O
.	O
</s>
