<s>
The	O
TK85	B-Device
was	O
a	O
ZX81	O
clone	O
made	O
by	O
Microdigital	O
Eletrônica	O
,	O
a	O
computer	O
company	O
located	O
in	O
Brazil	O
.	O
</s>
<s>
It	O
came	O
with	O
16	O
or	O
48KB	O
RAM	B-Architecture
,	O
and	O
had	O
a	O
ZX	B-Operating_System
Spectrum	I-Operating_System
–	O
style	O
case	O
,	O
similar	O
to	O
a	O
Timex	O
Sinclair	O
1500	O
.	O
</s>
<s>
Unlike	O
the	O
ZX81	O
,	O
the	O
TK85	B-Device
used	O
discrete	O
logic	O
circuits	O
instead	O
of	O
a	O
ULA	O
,	O
and	O
during	O
manufacture	O
several	O
chips	O
were	O
scraped	O
so	O
that	O
competitors	O
could	O
n't	O
copy	O
the	O
circuit	O
.	O
</s>
<s>
The	O
circuit	O
board	O
had	O
space	O
for	O
a	O
AY-3-8912	B-Device
sound	O
generator	O
chip	O
(	O
compatible	O
with	O
the	O
ZonX-81	O
sound	O
board	O
)	O
,	O
and	O
although	O
none	O
came	O
factory	O
installed	O
,	O
it	O
is	O
possible	O
to	O
add	O
the	O
necessary	O
circuits	O
.	O
</s>
<s>
The	O
TK85	B-Device
came	O
with	O
a	O
copy	O
of	O
the	O
8K	O
ZX81	B-Language
floating	I-Language
point	I-Language
BASIC	I-Language
,	O
and	O
an	O
additional	O
2K	O
EPROM	B-General_Concept
,	O
mapped	O
to	O
addresses	O
8192-10240	O
,	O
containing	O
machine	O
code	O
routines	O
for	O
use	O
with	O
tape	O
files	O
.	O
</s>
<s>
The	O
rear	O
of	O
the	O
computer	O
featured	O
a	O
TV	O
output	O
(	O
without	O
video	O
back	O
porch	O
)	O
,	O
"	O
EAR	O
"	O
and	O
"	O
MIC	O
"	O
sockets	O
for	O
connecting	O
to	O
an	O
external	O
tape	O
recorder	O
,	O
a	O
joystick	O
port	O
using	O
a	O
DIN	B-Architecture
socket	O
(	O
that	O
simulated	O
the	O
,,,	O
and	O
keys	O
)	O
,	O
a	O
ZX81	O
compatible	O
expansion	O
port	O
,	O
space	O
for	O
a	O
sound	O
output	O
socket	O
,	O
and	O
a	O
socket	O
for	O
the	O
9V	O
external	O
power	O
supply	O
.	O
</s>
<s>
Since	O
the	O
joystick	O
used	O
the	O
cursor	B-Device
keys	I-Device
,	O
and	O
due	O
to	O
the	O
circuitry	O
for	O
the	O
keyboard	O
,	O
it	O
was	O
n't	O
possible	O
to	O
detect	O
diagonal	O
directions	O
correctly	O
.	O
</s>
