<s>
IMLAC	B-Device
Corporation	I-Device
was	O
an	O
American	O
electronics	O
company	O
in	O
Needham	O
,	O
Massachusetts	O
,	O
that	O
manufactured	O
graphical	O
display	O
systems	O
,	O
mainly	O
,	O
the	O
PDS-1	O
and	O
PDS-4	O
,	O
in	O
the	O
1970s	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
low-cost	O
commercial	O
realization	O
of	O
Ivan	O
Sutherland	O
's	O
Sketchpad	B-Application
system	O
of	O
a	O
highly	O
interactive	O
computer	O
graphics	O
display	O
with	O
motion	O
.	O
</s>
<s>
The	O
PDS-1	O
was	O
functionally	O
similar	O
to	O
the	O
much	O
bigger	O
IBM	B-Device
2250	I-Device
,	O
which	O
cost	O
30	O
times	O
more	O
.	O
</s>
<s>
It	O
was	O
a	O
significant	O
step	O
forward	O
towards	O
computer	B-Device
workstations	I-Device
and	O
modern	O
displays	O
.	O
</s>
<s>
The	O
PDS-1	O
consisted	O
of	O
a	O
CRT	B-Device
monitor	I-Device
,	O
keyboard	O
,	O
light	B-Device
pen	I-Device
,	O
and	O
a	O
control	O
panel	O
on	O
a	O
small	O
desk	O
with	O
most	O
electronic	O
logic	O
in	O
the	O
desk	O
pedestal	O
.	O
</s>
<s>
The	O
electronics	O
included	O
a	O
simple	O
16-bit	O
minicomputer	B-Architecture
,	O
and	O
8-16	O
kilobytes	O
of	O
magnetic-core	O
memory	O
,	O
and	O
a	O
display	O
processor	O
for	O
driving	O
CRT	O
beam	O
movements	O
.	O
</s>
<s>
IMLAC	B-Device
is	O
not	O
an	O
acronym	O
,	O
but	O
is	O
the	O
name	O
of	O
a	O
poet	O
philosopher	O
from	O
Samuel	O
Johnson	O
's	O
novel	O
,	O
The	O
History	O
of	O
Rasselas	O
,	O
Prince	O
of	O
Abissinia	O
.	O
</s>
<s>
1968	O
:	O
Imlac	B-Device
founded	O
.	O
</s>
<s>
It	O
was	O
designed	O
to	O
be	O
used	O
mainly	O
by	O
a	O
proprietary	O
Fortran-coded	O
graphics	O
library	O
running	O
on	O
larger	O
computers	O
,	O
without	O
customer	O
programming	O
inside	O
the	O
terminal	O
.	O
</s>
<s>
1979	O
:	O
Imlac	B-Device
Corporation	I-Device
acquired	O
by	O
Hazeltine	O
Corporation	O
,	O
a	O
maker	O
of	O
text-only	O
terminals	O
.	O
</s>
<s>
1981	O
:	O
Hazeltine	O
's	O
Imlac	B-Device
Dynagraphic	O
Series	O
II	O
introduced	O
.	O
</s>
<s>
It	O
had	O
2Kx2K	O
resolution	O
,	O
192	O
kilobytes	O
of	O
ram	O
,	O
and	O
an	O
8086	O
microprocessor	B-Architecture
,	O
all	O
inside	O
the	O
monitor	O
unit	O
.	O
</s>
<s>
The	O
DEC	B-Device
GT40	I-Device
had	O
a	O
similar	O
design	O
and	O
price	O
point	O
to	O
the	O
PDS-1D	O
.	O
</s>
<s>
Its	O
desktop	O
electronics	O
were	O
more	O
compact	O
and	O
used	O
a	O
mass-produced	O
PDP	B-Device
11/05	I-Device
board	O
set	O
as	O
its	O
local	O
minicomputer	B-Architecture
.	O
</s>
<s>
The	O
monitor	O
was	O
a	O
14-inch	O
monochrome	O
vector	B-General_Concept
display	I-General_Concept
,	O
continually	O
refreshed	O
from	O
local	O
memory	O
.	O
</s>
<s>
Vector	B-General_Concept
displays	I-General_Concept
are	O
a	O
now-obsolete	O
alternative	O
to	O
raster	O
scan	O
displays	O
.	O
</s>
<s>
In	O
vector	B-General_Concept
displays	I-General_Concept
,	O
the	O
CRT	O
electron	O
beam	O
'	O
draws	O
 '	O
only	O
the	O
lines	O
and	O
curves	O
displayed	O
.	O
</s>
<s>
XGA-level	O
1024x768	O
black/white	O
resolution	O
requires	O
96	O
kilobytes	O
of	O
video	O
refresh	O
memory	O
,	O
12	O
times	O
more	O
than	O
a	O
basic	O
PDS-1	O
.	O
</s>
<s>
Vector	B-General_Concept
displays	I-General_Concept
were	O
good	O
for	O
showing	O
data	O
charts	O
,	O
modifying	O
line	O
drawings	O
and	O
CAD	B-Application
diagrams	O
,	O
tumbling	O
3-D	O
wire-frame	O
shapes	O
,	O
editing	O
text	O
,	O
laying	O
out	O
printed	O
pages	O
,	O
and	O
playing	O
simple	O
games	O
.	O
</s>
<s>
But	O
they	O
did	O
not	O
handle	O
colors	O
,	O
images	O
,	O
filled-in	O
areas	O
,	O
black-on-white	O
screens	O
,	O
or	O
WYSIWYG	B-Application
fidelity	O
to	O
the	O
fonts	O
of	O
professionally	O
printed	O
text	O
.	O
</s>
<s>
The	O
competing	O
lower	O
cost	O
Tektronix	B-General_Concept
4010	I-General_Concept
graphics	O
terminal	O
used	O
an	O
alternative	O
storage	B-General_Concept
tube	I-General_Concept
CRT	O
technology	O
which	O
required	O
no	O
continual	O
refresh	O
and	O
hence	O
no	O
local	O
computer	O
display	O
memory	O
at	O
all	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
operator	O
consoles	O
of	O
the	O
CDC	B-Device
6600	I-Device
formed	O
each	O
letter	O
all	O
at	O
once	O
by	O
sending	O
the	O
Charactron	B-General_Concept
CRT	O
electron	O
beam	O
through	O
a	O
metallic	O
stencil	O
mask	O
with	O
an	O
A-shaped	O
hole	O
,	O
or	O
through	O
a	O
B-shaped	O
hole	O
,	O
etc	O
.	O
</s>
<s>
The	O
PDS-1	O
'	O
s	O
display	O
processor	O
and	O
its	O
minicomputer	B-Architecture
ran	O
simultaneously	O
,	O
out	O
of	O
the	O
same	O
memory	O
.	O
</s>
<s>
Code	O
for	O
line	O
drawings	O
and	O
overall	O
layout	O
was	O
generated	O
on	O
the	O
fly	O
,	O
by	O
programs	O
running	O
on	O
the	O
local	O
minicomputer	B-Architecture
or	O
on	O
a	O
large	O
remote	O
computer	O
.	O
</s>
<s>
The	O
PDS-1	O
'	O
s	O
built-in	O
minicomputer	B-Architecture
was	O
needed	O
for	O
responding	O
to	O
user	O
keyboard	O
and	O
light	B-Device
pen	I-Device
interactions	O
quickly	O
,	O
without	O
delays	O
in	O
talking	O
to	O
a	O
remote	O
timeshared	B-General_Concept
large	O
computer	O
for	O
help	O
.	O
</s>
<s>
The	O
minicomputer	B-Architecture
's	O
main	O
task	O
was	O
to	O
build	O
and	O
modify	O
the	O
display	O
list	O
as	O
needed	O
for	O
the	O
next	O
refresh	O
cycle	O
.	O
</s>
<s>
To	O
minimize	O
costs	O
,	O
Imlac	B-Device
designed	O
their	O
own	O
simple	O
minicomputer	B-Architecture
with	O
as	O
few	O
registers	O
and	O
logic	O
gates	O
as	O
possible	O
.	O
</s>
<s>
It	O
was	O
a	O
single-accumulator	O
machine	O
much	O
like	O
a	O
DEC	B-Device
PDP-8	I-Device
,	O
except	O
using	O
16-bit	O
instructions	O
and	O
data	O
instead	O
of	O
12	O
bits	O
.	O
</s>
<s>
Programming	O
of	O
this	O
minicomputer	B-Architecture
was	O
via	O
assembler	O
language	O
.	O
</s>
<s>
Imlac	B-Device
eventually	O
added	O
a	O
self-hosted	O
Fortran	B-Application
compiler	O
with	O
hour-long	O
compiles	O
due	O
to	O
the	O
cramped	O
memory	O
.	O
</s>
<s>
Some	O
PDS	O
models	O
had	O
an	O
optional	O
IBM	B-Device
2310	I-Device
cartridge	O
disk	O
drive	O
or	O
8-inch	O
floppy	O
drive	O
.	O
</s>
<s>
The	O
PDS-1	O
electronics	O
were	O
built	O
from	O
7400	O
series	O
low-density	O
TTL	B-General_Concept
integrated	O
circuits	O
,	O
with	O
only	O
a	O
dozen	O
logic	O
gates	O
or	O
4	O
register	O
bits	O
per	O
DIP	B-Algorithm
chip	O
.	O
</s>
<s>
TTL	B-General_Concept
logic	I-General_Concept
ran	O
10x	O
faster	O
,	O
with	O
10	O
timing	O
pulses	O
per	O
core	O
memory	O
cycle	O
.	O
</s>
<s>
Instead	O
,	O
the	O
minicomputer	B-Architecture
created	O
a	O
long	O
sequence	O
of	O
short-stroke	O
display	O
instructions	O
.	O
</s>
<s>
The	O
software	O
used	O
a	O
quick	O
Bresenham	B-Algorithm
method	O
to	O
compute	O
intermediate	O
points	O
for	O
sloped	O
lines	O
without	O
doing	O
multiplies	O
or	O
divides	O
.	O
</s>
<s>
The	O
FRESS	O
hypertext	O
system	O
had	O
enhanced	O
capability	O
and	O
usability	O
if	O
accessed	O
from	O
a	O
PDS-1	O
system	O
;	O
the	O
user	O
could	O
make	O
hyperlinks	O
with	O
a	O
light	B-Device
pen	I-Device
and	O
create	O
them	O
simply	O
with	O
a	O
couple	O
of	O
keystrokes	O
.	O
</s>
<s>
Imlac	B-Device
display	O
systems	O
were	O
bundled	O
into	O
various	O
larger	O
commercial	O
products	O
involving	O
visual	O
design	O
and	O
specialized	O
software	O
.	O
</s>
<s>
Imlac	B-Device
sold	O
a	O
newspaper	O
layout	O
and	O
typesetting	O
system	O
using	O
PDS-1	O
called	O
CES	O
.	O
</s>
<s>
MCS	O
's	O
Anvil	O
mechanical	O
CAD	B-Application
system	O
used	O
later	O
Imlac	B-Device
workstations	B-Device
to	O
interactively	O
design	O
mechanical	O
parts	O
,	O
which	O
were	O
then	O
milled	O
out	O
automatically	O
from	O
metal	O
stock	O
.	O
</s>
<s>
Some	O
simple	O
applications	O
such	O
as	O
text	O
editors	O
were	O
entirely	O
coded	O
in	O
Imlac	B-Device
assembler	O
and	O
could	O
run	O
without	O
much	O
involvement	O
with	O
a	O
larger	O
computer	O
.	O
</s>
<s>
Hofstadter	O
composed	O
his	O
book	O
Gödel	O
,	O
Escher	O
,	O
Bach	O
on	O
an	O
Imlac	B-Device
editor	O
.	O
</s>
<s>
Those	O
applications	O
ran	O
mostly	O
on	O
an	O
expensive	O
timeshared	B-General_Concept
computer	O
,	O
which	O
sent	O
digested	O
image	O
data	O
to	O
the	O
Imlac	B-Device
,	O
which	O
ran	O
a	O
small	O
assembler	O
program	O
emulating	O
a	O
generic	O
graphics	O
terminal	O
.	O
</s>
<s>
The	O
two-player	O
Spacewar	B-Application
!	I-Application
</s>
<s>
Freeway	O
Crossing	O
,	O
an	O
early	O
predecessor	O
of	O
the	O
popular	O
arcade	O
game	O
Frogger	B-Application
,	O
was	O
created	O
on	O
a	O
PDS-1	O
as	O
part	O
of	O
a	O
psychology	O
experiment	O
in	O
1971	O
.	O
</s>
<s>
Mazewar	B-Application
,	O
the	O
first	O
online	O
multiplayer	O
computer	O
game	O
,	O
was	O
created	O
on	O
a	O
pair	O
of	O
PDS-1	O
'	O
s	O
.	O
</s>
<s>
Later	O
,	O
up	O
to	O
8	O
players	O
ran	O
on	O
PDS-1	O
stations	O
or	O
other	O
terminals	O
networked	O
to	O
the	O
MIT	O
host	O
PDP-10	B-Device
computer	O
running	O
the	O
Mazewar	B-Application
AI	B-Application
program	O
.	O
</s>
<s>
Mazewar	B-Application
games	O
between	O
MIT	O
and	O
Stanford	O
were	O
a	O
major	O
data	O
load	O
on	O
the	O
early	O
Arpanet	O
.	O
</s>
<s>
The	O
limitations	O
of	O
refreshed	O
or	O
storage	O
vector	B-General_Concept
displays	I-General_Concept
were	O
accepted	O
only	O
in	O
the	O
era	O
when	O
those	O
displays	O
were	O
much	O
cheaper	O
than	O
raster-scan	O
alternatives	O
.	O
</s>
<s>
Imlac	B-Device
PDS-1	I-Device
'	O
s	O
at	O
Xerox	O
PARC	O
impressed	O
them	O
with	O
its	O
interactivity	O
and	O
graphics	O
.	O
</s>
<s>
But	O
its	O
ugly	O
text	O
prompted	O
Chuck	O
Thacker	O
to	O
develop	O
the	O
experimental	O
bitmapped	O
Xerox	B-Device
Alto	I-Device
machine	O
in	O
1973	O
,	O
a	O
decade	O
before	O
that	O
much	O
memory	O
was	O
affordable	O
for	O
non-research	O
single-user	O
machines	O
.	O
</s>
<s>
And	O
Alto	B-Device
led	O
to	O
the	O
GUI	O
revolution	O
.	O
</s>
<s>
And	O
by	O
easily	O
programmed	O
personal	B-Device
workstations	I-Device
with	O
raster	O
graphics	O
such	O
as	O
the	O
Terak	B-Device
8510/a	I-Device
UCSD	O
Pascal	O
machine	O
and	O
the	O
high	O
performance	O
PERQ	B-Device
Unix	O
system	O
.	O
</s>
<s>
And	O
those	O
were	O
supplanted	O
by	O
microprocessor-based	O
mass-market	O
Macintoshes	B-Device
,	O
Windows	B-Application
PCs	I-Application
,	O
and	O
video	B-Device
game	I-Device
consoles	I-Device
.	O
</s>
<s>
And	O
now	O
by	O
single	O
chips	O
inside	O
smartphones	B-Application
.	O
</s>
<s>
In	O
2013	O
,	O
an	O
Imlac	B-Device
emulator	O
named	O
sImlac	O
was	O
written	O
.	O
</s>
