<s>
The	O
Elektronika	B-Device
MK-52	I-Device
(	O
)	O
is	O
an	O
RPN-programmable	O
calculator	O
manufactured	O
in	O
the	O
Soviet	O
Union	O
from	O
1983	O
to	O
1992	O
at	O
the	O
Quasar	O
and	O
Kvadr	O
plants	O
in	O
Ukraine	O
.	O
</s>
<s>
It	O
belongs	O
to	O
the	O
third	O
generation	O
of	O
Soviet	O
programmable	B-Application
calculators	I-Application
.	O
</s>
<s>
The	O
MK-52	B-Device
is	O
a	O
backwards	B-General_Concept
compatible	I-General_Concept
improvement	O
to	O
the	O
Elektronika	B-Device
MK-61	I-Device
,	O
the	O
main	O
changes	O
being	O
the	O
addition	O
of	O
an	O
internal	O
non-volatile	B-General_Concept
EEPROM	B-General_Concept
module	O
for	O
permanent	O
data	O
storage	O
,	O
a	O
diagnostic	O
slot	O
,	O
and	O
a	O
slot	O
for	O
separately	O
sold	O
ROM	B-Device
modules	O
.	O
</s>
<s>
The	O
machine	B-Language
code	I-Language
and	O
functionality	O
of	O
the	O
MK-52	B-Device
and	O
MK-61	B-Device
calculators	O
were	O
extensions	O
of	O
the	O
earlier	O
MK-54	O
,	O
B3-34	B-Device
,	O
and	O
B3-21	B-Device
Elektronika	O
calculators	O
.	O
</s>
<s>
The	O
MK-52	B-Device
is	O
the	O
only	O
calculator	O
known	O
to	O
have	O
internal	O
storage	O
in	O
the	O
form	O
of	O
an	O
EEPROM	B-General_Concept
module	O
.	O
</s>
<s>
As	O
with	O
many	O
Soviet	O
calculators	O
,	O
the	O
MK-52	B-Device
has	O
a	O
number	O
of	O
undocumented	O
functions	O
.	O
</s>
<s>
In	O
November	O
1988	O
,	O
the	O
MK-52	B-Device
went	O
into	O
space	O
on	O
the	O
Soyuz	O
TM-7	O
spacecraft	O
,	O
where	O
it	O
could	O
have	O
been	O
used	O
as	O
a	O
backup	O
to	O
the	O
onboard	O
computers	O
.	O
</s>
<s>
The	O
MK-52	B-Device
has	O
105	O
locations	O
of	O
volatile	B-General_Concept
program	I-General_Concept
memory	I-General_Concept
,	O
an	O
internal	O
EEPROM	B-General_Concept
module	O
(	O
with	O
512	O
bytes	B-Application
of	O
memory	O
)	O
,	O
and	O
15	O
7-byte	O
registers	O
.	O
</s>
<s>
It	O
has	O
a	O
relatively	O
dim	O
,	O
ten-digit	O
ИЛЦ2-12/8Л	O
green	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
display	I-General_Concept
;	O
these	O
ten	O
digits	O
are	O
apportioned	O
into	O
an	O
8	O
digit	O
mantissa	B-Algorithm
and	O
a	O
2	O
digit	O
exponent	O
.	O
</s>
<s>
The	O
MK-52	B-Device
has	O
an	O
expansion	O
port	O
to	O
which	O
various	O
ROM	B-Device
modules	O
can	O
be	O
attached	O
.	O
</s>
<s>
The	O
MK-52	B-Device
is	O
the	O
first	O
Soviet	O
micro-calculator	O
with	O
non-volatile	B-General_Concept
memory	I-General_Concept
;	O
this	O
is	O
provided	O
by	O
a	O
КР1601РР1	O
EEPROM	B-General_Concept
,	O
with	O
a	O
capacity	O
of	O
4kilobits	O
and	O
capable	O
of	O
10,000	O
rewrites	O
,	O
ensuring	O
security	O
for	O
programs	O
and	O
working	O
memory	O
when	O
powered	O
off	O
.	O
</s>
<s>
This	O
memory	O
is	O
capable	O
of	O
storing	O
up	O
to	O
512	O
1-byte	O
program	O
words	O
(	O
or	O
the	O
contents	O
of	O
72	O
7-byte	O
registers	O
)	O
and	O
exchanging	O
its	O
contents	O
with	O
the	O
calculator	O
's	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
calculator	O
is	O
fully	O
compatible	O
with	O
the	O
second-generation	O
models	O
(	O
B3-34	B-Device
and	O
MK-54	O
)	O
,	O
using	O
the	O
same	O
command	O
system	O
and	O
machine	B-Language
codes	I-Language
.	O
</s>
<s>
On	O
average	O
,	O
a	O
program	O
that	O
takes	O
all	O
105	O
steps	O
of	O
program	B-Device
memory	I-Device
and	O
15	O
registers	O
on	O
the	O
MC-52	O
will	O
be	O
equivalent	O
in	O
capability	O
to	O
approximately	O
140-150	O
steps	O
and	O
18	O
registers	O
on	O
the	O
B3-34	B-Device
.	O
</s>
<s>
In	O
addition	O
,	O
you	O
can	O
connect	O
an	O
external	O
ROM	B-Device
which	O
is	O
a	O
memory	O
expansion	O
unit	O
with	O
stored	O
games	O
and	O
mathematical	O
programs	O
,	O
produced	O
by	O
the	O
manufacturer	O
,	O
that	O
constitute	O
the	O
user	O
library	O
.	O
</s>
<s>
Manufacturers	O
have	O
produced	O
4	O
types	O
of	O
ROM	B-Device
cartridges	O
,	O
three	O
of	O
them	O
containing	O
various	O
mathematical	O
functions	O
,	O
and	O
one	O
,	O
the	O
BRP-4	O
,	O
containing	O
game	O
programs	O
:	O
</s>
<s>
In	O
1988	O
,	O
15,200	O
units	O
of	O
this	O
ROM	B-Device
were	O
manufactured	O
,	O
and	O
were	O
sold	O
at	O
a	O
price	O
of	O
16	O
rubles	O
;	O
</s>
<s>
The	O
MK-52	B-Device
has	O
two	O
main	O
modes	O
of	O
operation	O
:	O
automatic	O
mode	O
and	O
programming	O
mode	O
.	O
</s>
<s>
The	O
keystroke	O
sequence	O
switches	O
the	O
MK-52	B-Device
to	O
automatic	O
mode	O
,	O
while	O
switches	O
it	O
to	O
programming	O
mode	O
.	O
</s>
<s>
The	O
MK-52	B-Device
is	O
fully	O
capable	O
of	O
performing	O
Boolean	O
operations	O
on	O
binary	O
numbers	O
.	O
</s>
<s>
So	O
,	O
the	O
numbers	O
8.38	O
and	O
8.21	O
are	O
entered	O
into	O
the	O
MK-52	B-Device
and	O
the	O
OR	O
operation	O
is	O
performed	O
on	O
them	O
.	O
</s>
<s>
The	O
following	O
list	O
details	O
the	O
MK-52	B-Device
'	O
s	O
graphical	O
representation	O
of	O
hexadecimal	O
numbers	O
:	O
</s>
<s>
The	O
MK-52	B-Device
'	O
s	O
programming	O
commands	O
are	O
typed	O
into	O
the	O
MK-52	B-Device
in	O
programming	O
mode	O
and	O
are	O
then	O
executed	O
.	O
</s>
<s>
The	O
MK-52	B-Device
is	O
fully	O
capable	O
of	O
being	O
programmed	O
to	O
manage	O
memory	O
and	O
to	O
use	O
both	O
conditional	B-Application
and	O
unconditional	B-General_Concept
branching	I-General_Concept
.	O
</s>
<s>
Before	O
entering	O
a	O
program	O
to	O
volatile	B-General_Concept
memory	I-General_Concept
with	O
the	O
intention	O
of	O
saving	O
this	O
program	O
to	O
EEPROM	B-General_Concept
memory	O
,	O
the	O
EEPROM	B-General_Concept
program	O
space	O
to	O
be	O
saved	O
to	O
must	O
be	O
cleared	O
first	O
,	O
which	O
clears	O
the	O
volatile	B-General_Concept
memory	I-General_Concept
as	O
well	O
as	O
the	O
selected	O
area	O
of	O
the	O
EEPROM	B-General_Concept
memory	O
.	O
</s>
<s>
Each	O
program	O
step	O
requires	O
1	O
byte	B-Application
of	O
memory	O
and	O
each	O
data	O
register	O
requires	O
7	O
bytes	B-Application
of	O
memory	O
.	O
</s>
<s>
When	O
clearing	O
,	O
reading	O
,	O
or	O
writing	O
to	O
the	O
EEPROM	B-General_Concept
memory	O
,	O
the	O
address	O
and	O
range	O
are	O
specified	O
by	O
a	O
six-digit	O
number	O
,	O
preceded	O
by	O
a	O
non-zero	O
number	O
,	O
in	O
automatic	O
mode	O
:	O
e.g.	O
</s>
<s>
1aaaadd	O
specifies	O
that	O
dd	O
bytes	B-Application
are	O
to	O
be	O
stored	O
starting	O
at	O
memory	O
address	O
aaaa	O
.	O
</s>
<s>
A	O
two-position	O
data/program	O
switch	O
controls	O
whether	O
data	O
(	O
from	O
the	O
registers	O
)	O
or	O
program	B-Device
memory	I-Device
is	O
transferred	O
;	O
a	O
three-position	O
switch	O
is	O
used	O
to	O
select	O
read	O
,	O
write	O
,	O
and	O
clear	O
operations	O
.	O
</s>
<s>
The	O
Eketronika	O
MK-52	B-Device
originally	O
sold	O
for	O
115	O
rubles	O
.	O
</s>
<s>
As	O
typical	O
for	O
Soviet	O
electronics	O
,	O
technical	O
schematics	O
were	O
provided	O
for	O
the	O
MK-52	B-Device
when	O
it	O
was	O
purchased	O
,	O
facilitating	O
user	O
modification	O
and	O
repair	O
of	O
the	O
machine	O
.	O
</s>
<s>
There	O
is	O
a	O
host	O
of	O
games	O
available	O
for	O
the	O
MK-52	B-Device
.	O
</s>
<s>
The	O
MK-52	B-Device
'	O
s	O
undocumented	O
functions	O
tend	O
to	O
be	O
heavily	O
used	O
in	O
the	O
games	O
due	O
to	O
their	O
ability	O
to	O
make	O
unusual	O
calculations	O
and	O
produce	O
specialized	O
displays	O
.	O
</s>
<s>
In	O
November	O
1988	O
,	O
the	O
MK-52	B-Device
went	O
into	O
space	O
on	O
the	O
Soyuz	O
TM-7	O
spacecraft	O
,	O
where	O
it	O
could	O
have	O
been	O
used	O
to	O
calculate	O
the	O
trajectory	O
of	O
landing	O
in	O
the	O
event	O
of	O
an	O
onboard	O
computer	O
failure	O
.	O
</s>
<s>
There	O
is	O
currently	O
only	O
1	O
known	O
bug	O
in	O
the	O
MK-52	B-Device
:	O
the	O
MAX	O
function	O
returns	O
zero	O
if	O
one	O
of	O
its	O
two	O
arguments	O
is	O
zero	O
.	O
</s>
