<s>
The	O
Didaktik	B-Device
was	O
a	O
series	O
of	O
8-bit	O
home	O
computers	O
based	O
on	O
the	O
clones	O
of	O
Intel	B-General_Concept
8080	I-General_Concept
and	O
Zilog	B-General_Concept
Z80	I-General_Concept
processors	B-General_Concept
produced	O
by	O
Didaktik	B-Device
in	O
Skalica	O
,	O
in	O
the	O
former	O
Czechoslovakia	O
.	O
</s>
<s>
Initially	O
the	O
company	O
produced	O
PMD	O
85	O
compatible	B-General_Concept
machines	O
aimed	O
at	O
schools	O
,	O
then	O
switching	O
to	O
the	O
home	O
market	O
with	O
ZX	B-Operating_System
Spectrum	I-Operating_System
clones	O
.	O
</s>
<s>
Didaktik	B-Device
's	O
glory	O
diminished	O
with	O
the	O
falling	O
price	O
of	O
the	O
16-bit	B-Device
computers	I-Device
,	O
such	O
as	O
the	O
Atari	O
and	O
Amiga	B-Device
,	O
around	O
the	O
middle	O
of	O
the	O
1990s	O
until	O
it	O
was	O
finally	O
steam-rolled	O
by	O
the	O
PC	B-Device
soon	O
after	O
.	O
</s>
<s>
The	O
production	O
of	O
Didaktik	B-Device
computers	O
stopped	O
in	O
the	O
year	O
1994	O
.	O
</s>
<s>
Didaktik	B-Device
Alfa	O
was	O
produced	O
in	O
1986	O
,	O
as	O
a	O
"	O
more	O
professional	O
"	O
clone	O
of	O
PMD	O
85	O
.	O
</s>
<s>
It	O
featured	O
2.048MHz	O
Intel	B-General_Concept
8080	I-General_Concept
CPU	I-General_Concept
,	O
48KB	O
RAM	B-Architecture
,	O
8KB	O
ROM	B-Device
with	O
built-in	O
BASIC	O
,	O
good	O
keyboard	B-Device
(	O
compared	O
with	O
PMD	O
85	O
)	O
,	O
monitor	B-Device
video	O
output	O
(	O
but	O
no	O
TV	O
output	O
)	O
with	O
288×256	O
resolution	O
and	O
four	O
possible	O
colours	O
.	O
</s>
<s>
Despite	O
some	O
changes	O
in	O
ROM	B-Device
,	O
it	O
was	O
mostly	O
compatible	B-General_Concept
with	O
PMD	O
85	O
.	O
</s>
<s>
Didaktik	B-Device
Alfa	O
1	O
was	O
a	O
clone	O
of	O
PMD	O
85-1	O
,	O
Didaktik	B-Device
Alfa	O
2	O
of	O
PMD	O
85-2	O
.	O
</s>
<s>
Didaktik	B-Device
Beta	O
was	O
a	O
slightly	O
improved	O
version	O
of	O
previous	O
Didaktik	B-Device
Alfa	O
,	O
having	O
almost	O
identical	O
hardware	O
.	O
</s>
<s>
Didaktik	B-Device
Alfa	O
and	O
Beta	O
were	O
mostly	O
deployed	O
in	O
schools	O
to	O
replace	O
older	O
PMD	O
85	O
computers	O
.	O
</s>
<s>
Didaktik	B-Device
Gama	O
was	O
a	O
ZX	B-Operating_System
Spectrum	I-Operating_System
clone	O
with	O
80KB	O
RAM	B-Architecture
divided	O
into	O
two	O
switched	B-General_Concept
32KB	O
memory	O
banks	O
and	O
16KB	O
of	O
slower	O
RAM	B-Architecture
containing	O
graphical	O
data	O
for	O
video	O
output	O
,	O
while	O
the	O
size	O
of	O
ROM	B-Device
was	O
16KB	O
.	O
</s>
<s>
A	O
peripheral	O
interface	O
with	O
a	O
8255	B-Device
chip	O
was	O
added	O
,	O
providing	O
centronics	B-Device
plotter	O
and	O
printer	O
connections	O
and	O
a	O
Kempston	B-Device
joystick	I-Device
port	O
.	O
</s>
<s>
The	O
case	O
was	O
similar	O
to	O
that	O
of	O
the	O
ZX	O
Spectrum+	O
,	O
a	O
grey	O
or	O
black	O
box	O
in	O
A5	O
size	O
,	O
with	O
a	O
flat	O
plastic	O
keyboard	B-Device
and	O
connectors	O
mounted	O
on	O
the	O
rear	O
side	O
.	O
</s>
<s>
All	O
games	O
developed	O
for	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
48K	O
were	O
generally	O
compatible	B-General_Concept
with	O
this	O
computer	O
.	O
</s>
<s>
An	O
audio	B-Device
cassette	I-Device
was	O
used	O
as	O
data	O
storage	O
and	O
a	O
TV	O
served	O
as	O
a	O
monitor	B-Device
.	O
</s>
<s>
Didaktik	B-Device
Gama	O
was	O
produced	O
in	O
three	O
variants	O
:	O
the	O
first	O
,	O
Gama	O
'	O
87	O
,	O
fixed	O
some	O
bugs	B-Error_Name
in	O
the	O
original	O
ZX	B-Operating_System
Spectrum	I-Operating_System
ROM	B-Device
(	O
thus	O
breaking	O
compatibility	O
with	O
some	O
software	O
)	O
and	O
introduced	O
its	O
own	O
bugs	B-Error_Name
effectively	O
inhibiting	O
the	O
use	O
of	O
the	O
second	O
32KB	O
memory	O
bank	O
from	O
BASIC	O
.	O
</s>
<s>
Gama	O
'	O
88	O
fixed	O
the	O
original	O
ZX	B-Operating_System
Spectrum	I-Operating_System
bugs	B-Error_Name
in	O
a	O
more	O
compatible	B-General_Concept
way	O
,	O
and	O
also	O
fixed	O
the	O
memory	O
switching	O
bug	B-Error_Name
.	O
</s>
<s>
The	O
final	O
and	O
the	O
more	O
compatible	B-General_Concept
model	O
was	O
Gama	O
'	O
89	O
.	O
</s>
<s>
Production	O
of	O
Didaktik	B-Device
Gama	O
computers	O
ceased	O
in	O
1992	O
.	O
</s>
<s>
The	O
Didaktik	B-Device
M	O
introduced	O
in	O
1990	O
,	O
was	O
cheaper	O
and	O
simple	O
in	O
design	O
than	O
the	O
Gama	O
.	O
</s>
<s>
The	O
case	O
was	O
more	O
modern	O
,	O
with	O
an	O
ergonomic-like	O
shape	O
and	O
separate	O
arrow	O
keys	O
(	O
however	O
,	O
the	O
keyboard	B-Device
was	O
of	O
poorer	O
quality	O
)	O
.	O
</s>
<s>
Inside	O
there	O
was	O
only	O
64KB	O
of	O
total	O
memory	O
(	O
16KB	O
ROM	B-Device
and	O
48KB	O
RAM	B-Architecture
)	O
which	O
was	O
a	O
disappointment	O
in	O
comparison	O
to	O
the	O
Gama	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
whole	O
RAM	B-Architecture
was	O
implemented	O
by	O
a	O
single	O
set	O
of	O
64KB	O
chips	O
,	O
from	O
which	O
only	O
48KB	O
were	O
used	O
.	O
</s>
<s>
System	O
timings	O
were	O
different	O
to	O
the	O
original	O
ZX	B-Operating_System
Spectrum	I-Operating_System
,	O
which	O
prevented	O
some	O
software	O
from	O
displaying	O
timing	O
dependent	O
visual	O
effects	O
.	O
</s>
<s>
There	O
were	O
two	O
separated	O
connectors	O
for	O
joysticks	B-Device
and	O
one	O
connector	O
for	O
additional	O
hardware	O
,	O
such	O
as	O
a	O
printer	O
interface	O
.	O
</s>
<s>
Unlike	O
the	O
previous	O
version	O
of	O
Didaktik	B-Device
,	O
these	O
connectors	O
were	O
typical	O
"	O
socialistic	O
solution	O
"	O
,	O
with	O
no	O
compatible	B-General_Concept
peripherals	O
available	O
in	O
the	O
ČSSR	O
.	O
</s>
<s>
A	O
3.5-inch	O
floppy	O
disk	O
drive	O
,	O
called	O
D80	O
,	O
was	O
also	O
introduced	O
later	O
in	O
1992	O
,	O
simultaneously	O
to	O
the	O
release	O
of	O
the	O
Didaktik	B-Device
Kompakt	O
.	O
</s>
<s>
The	O
Didaktik	B-Device
Kompakt	O
from	O
1992	O
was	O
basically	O
a	O
Didaktik	B-Device
M	O
with	O
a	O
built-in	O
3.5-inch	O
720KB	O
floppy	O
drive	O
and	O
a	O
parallel	O
printer	O
port	O
.	O
</s>
