<s>
1K	B-Application
ZX	I-Application
Chess	I-Application
is	O
a	O
1982	O
chess	B-Application
program	O
for	O
the	O
unexpanded	O
Sinclair	O
ZX81	O
.	O
</s>
<s>
1K	O
ZX	O
Chess'''s	O
code	O
takes	O
up	O
only	O
672	O
bytes	O
in	O
memory	O
,	O
but	O
implements	O
chess	B-Application
rules	O
except	O
for	O
castling	O
,	O
promotion	O
,	O
and	O
en	O
passant	O
,	O
including	O
a	O
computer	O
opponent	O
.	O
</s>
<s>
It	O
was	O
the	O
smallest	O
implementation	O
of	O
chess	B-Application
on	O
any	O
computer	O
at	O
the	O
time	O
.	O
</s>
<s>
Developer	O
David	O
Horne	O
discussed	O
1K	B-Application
ZX	I-Application
Chess	I-Application
and	O
published	O
the	O
full	O
source	O
code	O
as	O
a	O
type-in	O
program	O
in	O
a	O
series	O
of	O
articles	O
in	O
Your	O
Computer	O
in	O
1982	O
and	O
1983	O
.	O
</s>
<s>
ReceptionPopular	O
Computing	O
Weekly	O
in	O
1982	O
called	O
1K	B-Application
ZX	I-Application
Chess	I-Application
"	O
one	O
of	O
the	O
most	O
interesting	O
ZX	O
tapes	O
to	O
pass	O
through	O
our	O
office	O
in	O
recent	O
weeks	O
"	O
.	O
</s>
<s>
It	O
approved	O
of	O
the	O
computer	O
displaying	O
moves	O
while	O
considering	O
them	O
and	O
noted	O
"	O
the	O
skills	O
which	O
went	O
into	O
writing	O
a	O
chess	B-Application
program	O
in	O
1K	O
of	O
machine	O
code	O
.	O
</s>
<s>
Tim	O
Harding	O
wrote	O
in	O
a	O
1985	O
book	O
on	O
computer	B-Application
chess	I-Application
that	O
"	O
the	O
man	O
who	O
did	O
it	O
must	O
be	O
some	O
sort	O
of	O
genius	O
"	O
.	O
</s>
<s>
While	O
describing	O
1K	B-Application
ZX	I-Application
Chess	I-Application
quality	O
of	O
play	O
as	O
"	O
so	O
appalling	O
that	O
it	O
would	O
be	O
hard	O
to	O
make	O
it	O
beat	O
you	O
"	O
and	O
criticizing	O
the	O
backward	O
algebraic	O
notation	O
,	O
he	O
concluded	O
that	O
"	O
the	O
program	O
is	O
nevertheless	O
a	O
fantastic	O
technical	O
achievement	O
"	O
.1K	O
ZX	O
Chess	O
came	O
in	O
second	O
place	O
for	O
best	O
software	O
in	O
a	O
poll	O
of	O
ZX81	O
users	O
.	O
</s>
<s>
Retrogaming	O
Times	O
Monthly	O
described	O
it	O
as	O
"	O
history	O
's	O
greatest	O
game	O
programming	O
feat	O
"	O
;	O
BootChess	O
author	O
Olivier	O
Poudade	O
praised	O
1K	O
ZX	O
Chess''s	O
code	O
,	O
stating	O
that	O
at	O
first	O
writing	O
a	O
smaller	O
chess	B-Application
program	O
"	O
seemed	O
impossible	O
...	O
Horne	O
had	O
nailed	O
it	O
so	O
much	O
already	O
"	O
.	O
</s>
