<s>
The	O
Memotech	B-Device
MTX500	I-Device
,	O
MTX512	B-Device
and	O
RS128	B-Device
are	O
a	O
series	O
of	O
Zilog	B-General_Concept
Z80A	I-General_Concept
processor-based	O
home	O
computers	O
released	O
by	O
Memotech	O
in	O
1983	O
and	O
1984	O
.	O
</s>
<s>
The	O
MTX500	B-Device
had	O
32	O
KB	O
of	O
RAM	B-Architecture
,	O
the	O
MTX512	B-Device
had	O
64KB	O
,	O
and	O
the	O
RS128	B-Device
had	O
128KB	O
.	O
</s>
<s>
Although	O
the	O
Z80A	B-General_Concept
could	O
only	O
address	O
a	O
maximum	O
of	O
64KB	O
at	O
a	O
time	O
,	O
the	O
MTX	O
and	O
RS128	B-Device
's	O
extra	O
memory	O
,	O
up	O
to	O
a	O
maximum	O
of	O
768KB	O
,	O
was	O
accessible	O
through	O
the	O
technique	O
of	O
page	B-General_Concept
switching	I-General_Concept
.	O
</s>
<s>
All	O
models	O
had	O
24KB	O
of	O
ROM	B-Device
accessible	O
in	O
the	O
first	O
16KB	O
of	O
address	O
space	O
.	O
</s>
<s>
The	O
extra	O
8KB	O
of	O
ROM	B-Device
was	O
available	O
through	O
page	B-General_Concept
switching	I-General_Concept
.	O
</s>
<s>
The	O
ROM	B-Device
could	O
be	O
switched	O
out	O
entirely	O
,	O
allowing	O
the	O
full	O
16-bit	O
address	O
space	O
to	O
be	O
used	O
for	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
computers	O
featured	O
an	O
all-aluminum	O
case	O
and	O
full-size	O
keyboard	O
with	O
real	O
keys	O
(	O
unlike	O
the	O
chiclet	B-Device
keyboard	I-Device
used	O
on	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
)	O
.	O
</s>
<s>
This	O
series	O
also	O
featured	O
support	O
for	O
plug-in	O
ROM	B-Protocol
cartridges	I-Protocol
(	O
a	O
little	O
like	O
the	O
BBC	B-Device
Micro	I-Device
)	O
.	O
</s>
<s>
The	O
most	O
popular	O
of	O
these	O
was	O
the	O
ISO	O
Pascal	B-Application
language	I-Application
from	O
HiSoft	B-Device
which	O
was	O
much	O
faster	O
than	O
interpreted	O
BASIC	O
.	O
</s>
<s>
A	O
considerable	O
addition	O
to	O
any	O
Memotech	O
system	O
was	O
the	O
hugely	O
expensive	O
FDX	O
system	O
which	O
added	O
5.25	B-Device
"	I-Device
floppy	B-Device
disk	I-Device
drives	I-Device
,	O
Winchester	O
hard	B-Device
disks	I-Device
and	O
CP/M	B-Application
2.2	O
operating	O
system	O
.	O
</s>
