<s>
The	O
Z-89	O
is	O
a	O
personal	B-Device
computer	I-Device
produced	O
by	O
Zenith	O
Data	O
Systems	O
(	O
ZDS	O
)	O
in	O
the	O
early	O
1980s	O
.	O
</s>
<s>
The	O
Zenith	B-Device
Z-89	I-Device
is	O
based	O
on	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
microprocessor	B-Architecture
running	O
at	O
2.048MHz	O
,	O
and	O
supports	O
the	O
HDOS	B-Application
and	O
CP/M	B-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
The	O
US$2295	O
Z-89	O
is	O
integrated	O
in	O
a	O
terminal-like	O
enclosure	O
with	O
a	O
non-detachable	O
keyboard	O
,	O
12-inch	O
monochrome	O
CRT	B-Device
with	O
a	O
80x25	O
screen	O
,	O
48KB	O
RAM	O
,	O
and	O
a	O
5.25	O
"	O
floppy	O
disk	O
drive	O
.	O
</s>
<s>
The	O
computer	O
has	O
two	O
small	O
card	O
cages	O
inside	O
the	O
cabinet	O
on	O
either	O
side	O
of	O
the	O
CRT	B-Device
,	O
each	O
of	O
which	O
accept	O
up	O
to	O
three	O
proprietary	O
circuit	O
cards	O
.	O
</s>
<s>
Upgrade	O
cards	O
available	O
for	O
this	O
included	O
disk	O
controller	O
cards	O
(	O
see	O
below	O
)	O
,	O
a	O
16	O
KB	O
RAM	O
card	O
that	O
upgrades	O
the	O
standard	O
48	O
KB	O
RAM	O
to	O
64	O
KB	O
,	O
a	O
RAM	O
memory	O
card	O
accessible	O
as	O
a	O
ramdrive	O
using	O
a	O
special	O
driver	O
(	O
above	O
the	O
Z80	B-General_Concept
's	O
64	O
KB	O
memory	O
limit	O
)	O
and	O
a	O
multi-serial	O
card	O
providing	O
extra	O
RS-232	O
ports	O
.	O
</s>
<s>
The	O
2	O
MHz	O
Z80	B-General_Concept
could	O
be	O
upgraded	O
to	O
4	O
MHz	O
.	O
</s>
<s>
In	O
1979	O
,	O
prior	O
to	O
Zenith	O
's	O
purchase	O
of	O
Heath	O
Company	O
,	O
Heathkit	O
designed	O
and	O
marketed	O
this	O
computer	O
in	O
kit	O
form	O
as	O
the	O
Heath	B-Device
H89	I-Device
,	O
assembled	O
as	O
the	O
WH89	O
,	O
and	O
without	O
the	O
floppy	O
but	O
with	O
a	O
cassette	O
interface	O
card	O
as	O
the	O
H88	O
.	O
</s>
<s>
Heath/Zenith	O
also	O
made	O
a	O
serial	B-General_Concept
terminal	I-General_Concept
,	O
the	O
H19/Z	O
-19	O
,	O
based	O
on	O
the	O
same	O
enclosure	O
(	O
with	O
a	O
blank	O
cover	O
over	O
the	O
diskette	O
drive	O
cut-out	O
)	O
and	O
terminal	B-General_Concept
controller	O
.	O
</s>
<s>
The	O
company	O
offered	O
an	O
upgrade	O
kit	O
to	O
convert	O
the	O
terminal	B-General_Concept
into	O
a	O
full	O
H89/Z	O
-89	O
computer	O
.	O
</s>
<s>
Another	O
configuration	O
,	O
the	O
Z-90	O
,	O
changes	O
the	O
floppy	O
drive	O
controller	O
from	O
the	O
hard-sectored	O
controller	O
(	O
max	O
100	O
kB	O
)	O
to	O
a	O
soft-sectored	O
controller	O
that	O
supported	O
double-sided	B-Architecture
,	O
double	O
density	O
,	O
96tpi	O
drives	O
with	O
a	O
capacity	O
of	O
800	O
kB	O
.	O
</s>
<s>
The	O
H37/Z	O
-37	O
supports	O
up	O
to	O
two	O
Double-Sided	B-Architecture
,	O
Double	O
Density	O
,	O
96tpi	O
5.25	O
"	O
drives	O
and	O
requires	O
the	O
soft-sectored	O
controller	O
.	O
</s>
<s>
Creative	B-General_Concept
Computing	I-General_Concept
described	O
the	O
Heath	B-Device
H89	I-Device
as	O
"	O
the	O
most	O
professional	O
looking	O
"	O
microcomputer	O
available	O
.	O
</s>
<s>
BYTE	B-Application
wrote	O
that	O
the	O
H89	O
"	O
has	O
a	O
number	O
of	O
unique	O
hardware	O
features	O
and	O
the	O
same	O
excellent	O
software	O
support	O
and	O
documentation	O
as	O
the	O
original	O
H-8	B-Device
system	O
"	O
.	O
</s>
