<s>
Optimized	B-Operating_System
Systems	I-Operating_System
Software	I-Operating_System
(	O
OSS	O
)	O
was	O
a	O
company	O
that	O
produced	O
disk	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
programming	O
languages	O
with	O
integrated	O
development	O
environments	O
,	O
and	O
applications	O
primarily	O
for	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
of	O
home	O
computers	O
.	O
</s>
<s>
OSS	O
was	O
best	O
known	O
for	O
their	O
enhanced	O
versions	O
of	O
Atari	B-Operating_System
DOS	I-Operating_System
(	O
OS	O
A+	O
,	O
then	O
DOS	B-Application
XL	I-Application
)	O
,	O
Atari	B-Language
BASIC	I-Language
(	O
first	O
BASIC	B-Language
A+	I-Language
,	O
then	O
BASIC	O
XL	O
,	O
and	O
BASIC	O
XE	O
)	O
,	O
and	O
the	O
Atari	B-Application
Assembler	I-Application
Editor	I-Application
(	O
EASMD	O
,	O
then	O
MAC/65	B-Application
)	O
,	O
all	O
of	O
which	O
were	O
substantially	O
improved	O
over	O
Atari	O
's	O
products	O
,	O
as	O
well	O
as	O
the	O
Action	B-Language
!	I-Language
</s>
<s>
OSS	O
also	O
sold	O
some	O
software	O
for	O
the	O
Apple	B-Device
II	I-Device
.	O
</s>
<s>
OSS	O
transitioned	O
to	O
16-bit	O
platforms	O
with	O
Personal	O
Pascal	O
for	O
the	O
Atari	B-Device
ST	I-Device
and	O
Personal	O
Prolog	O
for	O
Macintosh	B-Device
(	O
which	O
was	O
also	O
advertised	O
for	O
the	O
Atari	B-Device
ST	I-Device
,	O
but	O
may	O
not	O
have	O
been	O
released	O
)	O
.	O
</s>
<s>
Optimized	B-Operating_System
Systems	I-Operating_System
Software	I-Operating_System
was	O
formed	O
in	O
early	O
1981	O
by	O
Bill	O
Wilkinson	O
,	O
Mike	O
Peters	O
,	O
Paul	O
Laughton	O
,	O
and	O
Kathleen	O
O'Brien	O
.	O
</s>
<s>
Laughton	O
,	O
the	O
primary	O
author	O
of	O
Atari	B-Language
BASIC	I-Language
,	O
was	O
still	O
employed	O
by	O
Atari	O
,	O
Inc	O
.	O
at	O
the	O
time	O
,	O
and	O
had	O
permission	O
to	O
be	O
involved	O
with	O
OSS	O
from	O
his	O
manager	O
.	O
</s>
<s>
O'Brien	O
wrote	O
the	O
Atari	B-Application
Assembler	I-Application
Editor	I-Application
for	O
Atari	O
.	O
</s>
<s>
OSS	O
purchased	O
Atari	B-Language
BASIC	I-Language
,	O
Atari	B-Operating_System
DOS	I-Operating_System
,	O
and	O
the	O
Atari	B-Application
Assembler	I-Application
Editor	I-Application
products	O
from	O
Shepardson	B-Device
Microsystems	I-Device
who	O
had	O
concluded	O
that	O
their	O
BASIC	O
and	O
DOS	O
products	O
were	O
not	O
viable	O
.	O
</s>
<s>
The	O
new	O
company	O
enhanced	O
the	O
programs	O
,	O
renaming	O
them	O
OS/A	O
+	O
(	O
the	O
Disk	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
)	O
,	O
BASIC	B-Language
A+	I-Language
(	O
a	O
disk-based	O
language	O
)	O
,	O
and	O
EASMD	O
(	O
an	O
update	O
to	O
the	O
Assembler	O
Editor	O
)	O
.	O
</s>
<s>
The	O
products	O
they	O
released	O
over	O
the	O
next	O
several	O
years	O
became	O
respected	O
among	O
Atari	O
programmers	O
,	O
particularly	O
the	O
MAC/65	B-Application
assembler	O
,	O
the	O
Action	B-Language
!	I-Language
</s>
<s>
Atari	B-Operating_System
DOS	I-Operating_System
2.0S	O
consisted	O
of	O
two	O
portions	O
,	O
a	O
memory-resident	O
portion	O
that	O
facilitated	O
access	O
to	O
disk	O
files	O
by	O
programs	O
,	O
and	O
a	O
disk-resident	O
portion	O
providing	O
menu-driven	O
utilities	O
to	O
format	O
,	O
copy	O
,	O
delete	O
,	O
rename	O
,	O
and	O
otherwise	O
manipulate	O
files	O
on	O
Atari	O
's	O
810	O
disk	O
drive	O
.	O
</s>
<s>
OS/A	O
+	O
2.0	O
,	O
2.1	O
was	O
a	O
disk-based	O
replacement	O
for	O
the	O
Atari	B-Operating_System
DOS	I-Operating_System
and	O
the	O
Apple	B-Device
II	I-Device
DOS	O
.	O
</s>
<s>
It	O
replaced	O
the	O
menu-driven	O
utilities	O
with	O
a	O
compact	O
command	O
line	O
approach	O
similar	O
to	O
CP/M	B-Application
(	O
and	O
later	O
,	O
MS-DOS	B-Application
)	O
.	O
</s>
<s>
When	O
first	O
introduced	O
at	O
the	O
West	O
Coast	O
Computer	O
Faire	O
,	O
the	O
program	O
was	O
named	O
CP/A	O
,	O
but	O
a	O
lawyer	O
from	O
Digital	O
Research	O
(	O
owners	O
of	O
CP/M	B-Application
)	O
visited	O
the	O
booth	O
and	O
the	O
name	O
was	O
changed	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
strict	O
"	O
8.3	O
"	O
naming	O
scheme	O
(	O
eight	O
alphanumeric	O
characters	O
with	O
a	O
three	O
character	O
extension	O
)	O
was	O
replaced	O
by	O
"	O
long	O
"	O
filenames	O
,	O
similar	O
to	O
the	O
Microsoft	B-Application
DOS	I-Application
transition	O
to	O
VFAT	B-Application
in	O
1995	O
.	O
</s>
<s>
However	O
,	O
unlike	O
VFAT	B-Application
,	O
OS/A	O
+	O
4.1	O
disks	O
were	O
not	O
backward	O
compatible	O
with	O
earlier	O
systems	O
;	O
Atari	B-Operating_System
DOS	I-Operating_System
or	O
OS/A	O
+	O
2.1	O
could	O
not	O
read	O
disks	O
formatted	O
by	O
OS/A	O
+	O
4.1	O
,	O
breaking	O
backward	O
compatibility	O
.	O
</s>
<s>
OSS	O
did	O
reissue	O
OS/A	O
+	O
4.1	O
for	O
a	O
brief	O
period	O
when	O
they	O
decided	O
not	O
to	O
modify	O
DOS	B-Application
XL	I-Application
for	O
double-sided	O
disk	O
support	O
.	O
</s>
<s>
DOS	B-Application
XL	I-Application
was	O
designed	O
to	O
replace	O
OS/A	O
+	O
.	O
</s>
<s>
Due	O
to	O
lack	O
of	O
demand	O
and	O
Atari	O
working	O
on	O
a	O
new	O
version	O
of	O
DOS	O
,	O
OSS	O
decided	O
to	O
halt	O
development	O
of	O
DOS	B-Application
XL	I-Application
4	O
and	O
reissue	O
OS/A	O
+	O
version	O
4.1	O
.	O
</s>
<s>
The	O
team	O
that	O
developed	O
Atari	B-Language
BASIC	I-Language
while	O
at	O
Shepherdson	O
Microsystems	O
developed	O
a	O
series	O
of	O
three	O
increasingly	O
sophisticated	O
BASIC	B-Language
interpreters	I-Language
at	O
OSS	O
.	O
</s>
<s>
Atari	B-Language
BASIC	I-Language
was	O
designed	O
to	O
fit	O
in	O
an	O
8K	O
cartridge	O
,	O
with	O
an	O
optional	O
cartridge	O
for	O
the	O
second	O
slot	O
of	O
the	O
Atari	B-Device
800	I-Device
adding	O
additional	O
capability	O
.	O
</s>
<s>
Instead	O
,	O
OSS	O
produced	O
the	O
disk-based	O
BASIC	B-Language
A	I-Language
Plus	I-Language
(	O
or	O
BASIC	B-Language
A+	I-Language
)	O
,	O
which	O
is	O
compatible	O
with	O
Atari	B-Language
BASIC	I-Language
,	O
corrects	O
several	O
bugs	O
,	O
and	O
adds	O
many	O
new	O
features	O
.	O
</s>
<s>
Because	O
BASIC	B-Language
A+	I-Language
had	O
to	O
be	O
purchased	O
,	O
programs	O
developed	O
using	O
its	O
extended	O
features	O
could	O
not	O
be	O
shared	O
with	O
people	O
who	O
did	O
not	O
own	O
the	O
interpreter	B-Application
.	O
</s>
<s>
BASIC	O
XL	O
is	O
a	O
bank-selected	O
cartridge	O
version	O
of	O
the	O
language	O
that	O
replaced	O
BASIC	B-Language
A+	I-Language
.	O
</s>
<s>
In	O
Atari	B-Language
BASIC	I-Language
,	O
any	O
GOTO	O
searches	O
the	O
entire	O
program	O
for	O
the	O
provided	O
line	O
number	O
,	O
and	O
FOR	O
...	O
NEXT	O
loops	O
use	O
the	O
same	O
code	O
.	O
</s>
<s>
The	O
downside	O
is	O
that	O
an	O
address	O
becomes	O
invalid	O
if	O
the	O
program	O
is	O
edited	O
during	O
runtime	O
,	O
preventing	O
it	O
from	O
being	O
CONTinued	O
,	O
unlike	O
Atari	B-Language
BASIC	I-Language
which	O
generally	O
allows	O
this	O
after	O
any	O
edit	O
.	O
</s>
<s>
Based	O
on	O
the	O
original	O
Atari	B-Application
Assembler	I-Application
Editor	I-Application
,	O
it	O
was	O
released	O
in	O
1981	O
on	O
disk	O
.	O
</s>
<s>
It	O
was	O
superseded	O
by	O
MAC/65	B-Application
.	O
</s>
<s>
MAC/65	B-Application
is	O
a	O
6502	B-General_Concept
editor	O
and	O
assembler	O
originally	O
released	O
on	O
disk	O
in	O
1982	O
,	O
then	O
on	O
a	O
bank-switched	O
"	O
supercartridge	O
"	O
in	O
1983	O
which	O
includes	O
an	O
integrated	O
debugger	B-Application
(	O
DDT	O
)	O
.	O
</s>
<s>
Like	O
Atari	B-Language
BASIC	I-Language
,	O
MAC/65	B-Application
uses	O
line-numbered	O
source	O
code	O
and	O
tokenizes	O
each	O
line	O
as	O
it	O
is	O
entered	O
.	O
</s>
<s>
The	O
MAC/65	B-Application
Toolkit	O
disk	O
contains	O
additional	O
code	O
and	O
examples	O
.	O
</s>
<s>
BUG/65	O
is	O
a	O
machine	O
language	O
debugger	B-Application
.	O
</s>
<s>
It	O
was	O
initially	O
included	O
with	O
MAC/65	B-Application
,	O
but	O
the	O
cartridge-based	O
version	O
of	O
the	O
assembler	O
added	O
its	O
own	O
debugger	B-Application
,	O
DDT	O
.	O
</s>
<s>
BUG/65	O
was	O
later	O
added	O
to	O
DOS	B-Application
XL	I-Application
.	O
</s>
<s>
A	O
cartridge-based	O
development	O
system	O
for	O
a	O
readable	O
ALGOL-like	B-Language
language	O
that	O
compiles	B-Language
to	O
efficient	O
6502	B-General_Concept
code	O
.	O
</s>
<s>
Action	B-Language
!	I-Language
</s>
<s>
combines	O
a	O
full-screen	O
editor	O
with	O
a	O
compiler	B-Language
that	O
generates	O
code	O
directly	O
to	O
memory	O
without	O
involving	O
disk	O
access	O
.	O
</s>
<s>
The	O
language	O
found	O
a	O
niche	O
for	O
being	O
over	O
a	O
hundred	O
times	O
faster	O
than	O
Atari	B-Language
BASIC	I-Language
,	O
but	O
much	O
easier	O
to	O
program	O
in	O
than	O
assembly	O
language	O
.	O
</s>
<s>
Compiled	B-Language
Action	B-Language
!	I-Language
</s>
<s>
The	O
separately	O
available	O
Action	B-Language
!	I-Language
</s>
<s>
Run-Time	O
Package	O
overcomes	O
this	O
limitation	O
and	O
allows	O
distribution	O
of	O
Action	B-Language
!	I-Language
-compiled	O
projects	O
.	O
</s>
<s>
The	O
Action	B-Language
!	I-Language
</s>
<s>
Toolkit	O
(	O
originally	O
called	O
the	O
Programmer	O
's	O
Aid	O
Disk	O
,	O
or	O
PAD	O
)	O
contains	O
additional	O
code	O
and	O
examples	O
for	O
use	O
with	O
the	O
Action	B-Language
!	I-Language
</s>
<s>
C/65	O
is	O
a	O
compiler	B-Language
developed	O
by	O
LightSpeed	O
Software	O
for	O
a	O
subset	O
of	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
C/65	O
outputs	O
assembly	O
source	O
code	O
.	O
</s>
<s>
An	O
assembler	O
like	O
MAC/65	B-Application
is	O
needed	O
to	O
create	O
an	O
executable	O
file	O
.	O
</s>
<s>
Tiny	O
C	B-Language
,	O
stylized	O
as	O
tiny-c	O
,	O
is	O
an	O
interpreter	B-Application
for	O
a	O
subset	O
of	O
the	O
C	B-Language
programming	I-Language
language	I-Language
;	O
it	O
was	O
developed	O
by	O
Tiny	O
C	B-Language
Associates	O
.	O
</s>
<s>
A	O
one-pass	O
,	O
machine	O
code	O
generating	O
compiler	B-Language
for	O
the	O
Pascal	O
language	O
developed	O
by	O
J	O
.	O
Lohse	O
for	O
the	O
Atari	B-Device
ST	I-Device
and	O
released	O
by	O
OSS	O
in	O
1987	O
.	O
</s>
<s>
SpeedRead+	O
is	O
a	O
speed	O
reading	O
tutor	O
developed	O
for	O
the	O
Atari	B-Device
8-bit	I-Device
and	O
Apple	B-Device
II	I-Device
computers	O
.	O
</s>
<s>
Basic	O
XL	O
outsold	O
Action	B-Language
!	I-Language
</s>
<s>
MAC/65	B-Application
outsold	O
Action	B-Language
!	I-Language
</s>
