<s>
The	O
Hazeltine	B-Device
1500	I-Device
was	O
a	O
popular	O
smart	O
terminal	O
introduced	O
by	O
Hazeltine	O
Corporation	O
in	O
April	O
1977	O
at	O
a	O
price	O
of	O
.	O
</s>
<s>
Using	O
a	O
microprocessor	B-Architecture
and	O
semiconductor	O
random	B-Architecture
access	I-Architecture
memory	I-Architecture
,	O
it	O
implemented	O
the	O
basic	O
features	O
of	O
the	O
earlier	O
Hazeltine	B-Device
2000	I-Device
in	O
a	O
much	O
smaller	O
and	O
less	O
expensive	O
system	O
,	O
less	O
than	O
half	O
the	O
price	O
.	O
</s>
<s>
It	O
came	O
to	O
market	O
just	O
as	O
the	O
microcomputer	B-Architecture
revolution	O
was	O
taking	O
off	O
,	O
and	O
the	O
1500	O
was	O
very	O
popular	O
among	O
early	O
hobbyist	O
users	O
.	O
</s>
<s>
Two	O
modified	O
versions	O
were	O
introduced	O
in	O
June	O
1977	O
,	O
the	O
Hazeltine	B-Device
1510	I-Device
and	O
Hazeltine	B-Device
1520	I-Device
.	O
</s>
<s>
The	O
final	O
entry	O
to	O
the	O
1500	O
series	O
was	O
the	O
Hazeltine	B-Device
1552	I-Device
introduced	O
in	O
August	O
1979	O
at	O
.	O
</s>
<s>
It	O
added	O
a	O
VT52	B-Application
emulation	O
mode	O
,	O
separate	O
cursor	B-Device
keys	I-Device
,	O
and	O
graphics	O
characters	O
.	O
</s>
<s>
The	O
1500	O
used	O
an	O
Intel	B-General_Concept
8080A	I-General_Concept
processor	O
with	O
2kB	O
of	O
ROM	O
for	O
the	O
basic	O
operations	O
,	O
and	O
2kB	O
of	O
RAM	B-Architecture
as	O
the	O
character	O
buffer	O
(	O
4kB	O
in	O
the	O
1510/1520	O
)	O
.	O
</s>
<s>
The	O
12	O
"	O
CRT	B-Device
used	O
P4	O
"	O
white	O
"	O
phosphor	O
.	O
</s>
<s>
Like	O
earlier	O
models	O
in	O
the	O
Hazeltine	O
line	O
,	O
the	O
1500	O
supported	O
both	O
an	O
RS-232	O
interface	O
,	O
with	O
speeds	O
from	O
110	O
up	O
to	O
19,200	O
bps	O
,	O
as	O
well	O
as	O
a	O
20mA	O
current	O
loop	O
,	O
used	O
by	O
teletype	O
systems	O
and	O
still	O
common	O
due	O
to	O
the	O
widespread	O
use	O
of	O
Teletype	B-Application
Model	I-Application
33	I-Application
as	O
ad	O
hoc	O
terminals	O
.	O
</s>
<s>
The	O
command	O
set	O
for	O
Hazeltine	B-Device
terminals	I-Device
was	O
fairly	O
simple	O
,	O
consisting	O
mostly	O
of	O
line	O
editing	O
and	O
cursor	O
positioning	O
commands	O
.	O
</s>
<s>
The	O
tilde	O
,	O
was	O
used	O
as	O
the	O
escape	B-Algorithm
character	I-Algorithm
,	O
or	O
as	O
they	O
referred	O
to	O
it	O
,	O
the	O
"	O
lead-in	O
code	O
"	O
.	O
</s>
<s>
Sending	O
locked	O
the	O
keyboard	B-Device
,	O
while	O
unlocked	O
it	O
again	O
.	O
</s>
<s>
When	O
this	O
was	O
on	O
,	O
the	O
terminal	O
only	O
accepted	O
input	O
from	O
the	O
keyboard	B-Device
,	O
ignoring	O
data	O
from	O
the	O
host	O
.	O
</s>
