<s>
The	O
Acorn	B-Device
Atom	I-Device
is	O
a	B-General_Concept
home	O
computer	O
made	O
by	O
Acorn	O
Computers	O
Ltd	O
from	O
1979	O
to	O
1982	O
,	O
when	O
it	O
was	O
replaced	O
by	O
the	O
BBC	B-Device
Micro	I-Device
.	O
</s>
<s>
The	O
BBC	B-Device
Micro	I-Device
began	O
life	O
as	O
an	O
upgrade	O
to	O
the	O
Atom	O
,	O
originally	O
known	O
as	O
the	O
Proton	O
.	O
</s>
<s>
The	O
Atom	O
was	O
a	B-General_Concept
progression	O
of	O
the	O
MOS	O
Technology	O
6502-based	O
machines	O
that	O
the	O
company	O
had	O
been	O
making	O
from	O
1979	O
.	O
</s>
<s>
The	O
Atom	O
was	O
a	B-General_Concept
cut-down	O
Acorn	B-Device
System	I-Device
3	I-Device
without	O
a	B-General_Concept
disk	O
drive	O
but	O
with	O
an	O
integral	O
keyboard	B-Device
and	O
cassette	B-Device
tape	I-Device
interface	O
,	O
sold	O
in	O
either	O
kit	O
or	O
complete	O
form	O
.	O
</s>
<s>
In	O
1979	O
it	O
was	O
priced	O
between	O
£120	O
in	O
kit	O
form	O
,	O
£170	O
(	O
)	O
ready	O
assembled	O
,	O
to	O
over	O
£200	O
for	O
the	O
fully	O
expanded	O
version	O
with	O
12KB	O
of	O
RAM	B-Architecture
and	O
the	O
floating-point	B-Algorithm
extension	O
ROM	B-Device
.	O
</s>
<s>
The	O
minimum	O
Atom	O
had	O
2KB	O
of	O
RAM	B-Architecture
and	O
8KB	O
of	O
ROM	B-Device
,	O
with	O
the	O
maximum	O
specification	O
machine	O
having	O
12KB	O
of	O
each	O
.	O
</s>
<s>
An	O
additional	O
floating-point	B-Algorithm
ROM	B-Device
was	O
also	O
available	O
.	O
</s>
<s>
The	O
2KB	O
of	O
RAM	B-Architecture
was	O
divided	O
between	O
1KB	O
of	O
Block	O
Zero	O
RAM	B-Architecture
(	O
including	O
the	O
256	O
bytes	O
of	O
"	O
zero	O
page	O
"	O
)	O
and	O
512	O
bytes	O
for	O
the	O
screen	O
(	O
text	O
mode	O
)	O
and	O
only	O
512	O
bytes	O
for	O
programs	O
(	O
presumably	O
in	O
text	O
mode	O
,	O
mode	O
0	O
,	O
and	O
graphics	O
not	O
available	O
)	O
,	O
i.e.	O
</s>
<s>
written	O
in	O
the	O
BASIC	B-Language
language	I-Language
.	O
</s>
<s>
When	O
expanded	O
up	O
to	O
a	B-General_Concept
total	O
of	O
12KB	O
RAM	B-Architecture
,	O
the	O
split	O
is	O
1KB	O
,	O
5KB	O
for	O
programs	O
,	O
and	O
up	O
to	O
6KB	O
for	O
the	O
high-resolution	O
graphics	O
(	O
the	O
screen	O
memory	O
could	O
be	O
expanded	O
independently	O
from	O
the	O
lower	O
part	O
of	O
the	O
address	O
space	O
)	O
.	O
</s>
<s>
Block	O
Zero	O
,	O
was	O
used	O
by	O
the	O
CPU	B-General_Concept
for	O
stack	O
storage	O
,	O
by	O
the	O
OS	O
,	O
and	O
by	O
the	O
Atom	O
BASIC	O
for	O
storage	O
of	O
the	O
27	O
variables	O
.	O
</s>
<s>
It	O
had	O
an	O
MC6847	B-General_Concept
Video	B-General_Concept
Display	I-General_Concept
Generator	I-General_Concept
(	O
VDG	O
)	O
video	B-General_Concept
chip	I-General_Concept
,	O
allowing	O
for	O
both	O
text	O
and	O
graphics	O
modes	O
.	O
</s>
<s>
It	O
could	O
be	O
connected	O
to	O
a	B-General_Concept
TV	O
or	O
modified	O
to	O
output	O
to	O
a	B-General_Concept
video	O
monitor	O
.	O
</s>
<s>
Since	O
the	O
MC6847	B-General_Concept
could	O
only	O
output	O
at	O
60Hz	O
,	O
meaning	O
that	O
the	O
video	O
could	O
not	O
be	O
resolved	O
on	O
a	B-General_Concept
large	O
proportion	O
of	O
European	O
TV	O
sets	O
,	O
a	B-General_Concept
50Hz	O
PAL	B-Language
colour	O
card	O
was	O
later	O
made	O
available	O
.	O
</s>
<s>
It	O
had	O
a	B-General_Concept
built-in	O
minor	O
variation	O
of	O
Acorn	O
System	O
BASIC	O
,	O
a	B-General_Concept
fast	O
but	O
idiosyncratic	O
version	O
of	O
the	O
BASIC	B-Language
programming	I-Language
language	I-Language
developed	O
by	O
Sophie	O
Wilson	O
,	O
which	O
included	O
indirection	O
operators	O
(	O
similar	O
to	O
PEEK	B-Language
and	I-Language
POKE	I-Language
)	O
for	O
bytes	O
and	O
words	O
(	O
of	O
4	O
bytes	O
each	O
)	O
;	O
the	O
use	O
of	O
a	B-General_Concept
semi-colon	O
to	O
separate	O
statements	O
on	O
the	O
same	O
line	O
of	O
code	O
(	O
instead	O
of	O
the	O
colon	O
used	O
by	O
most	O
if	O
not	O
all	O
other	O
versions	O
of	O
BASIC	O
)	O
;	O
and	O
the	O
option	O
of	O
labels	O
rather	O
than	O
line	O
numbers	O
for	O
GOTO	O
and	O
GOSUB	O
commands	O
.	O
</s>
<s>
Assembly	B-Language
code	I-Language
could	O
be	O
included	O
within	O
a	B-General_Concept
BASIC	O
program	O
,	O
because	O
the	O
BASIC	B-Language
interpreter	I-Language
also	O
contained	O
an	O
assembler	B-Language
for	O
the	O
6502	B-General_Concept
assembly	B-Language
language	I-Language
which	O
assembled	O
the	O
inline	O
code	O
during	O
program	O
execution	O
and	O
then	O
executed	O
it	O
.	O
</s>
<s>
A	B-General_Concept
byte	O
vector	O
to	O
could	O
be	O
ensioned	O
and	O
then	O
referred	O
to	O
with	O
the	O
string	O
operator	O
to	O
be	O
treated	O
as	O
a	B-General_Concept
string	O
.	O
</s>
<s>
In	O
late	O
1982	O
,	O
Acorn	O
released	O
an	O
upgrade	O
board	O
for	O
the	O
Atom	O
which	O
allowed	O
users	O
to	O
switch	O
between	O
Atom	O
BASIC	O
and	O
the	B-Language
more	I-Language
advanced	I-Language
"	I-Language
BBC	I-Language
BASIC	I-Language
"	I-Language
used	O
by	O
the	O
BBC	B-Device
Micro	I-Device
.	O
</s>
<s>
The	O
upgrade	O
was	O
purely	O
to	O
the	O
programming	O
language	O
;	O
the	O
Atom	O
's	O
hardware	O
capabilities	O
remained	O
unchanged	O
,	O
and	O
hence	O
,	O
contrary	O
to	O
some	O
pre-release	O
beliefs	O
,	O
the	O
BBC	B-Language
BASIC	I-Language
ROM	B-Device
did	O
not	O
allow	O
Atom	O
users	O
to	O
run	O
commercial	O
BBC	B-Device
Micro	I-Device
software	O
,	O
since	O
nearly	O
all	O
of	O
it	O
took	O
advantage	O
of	O
the	O
BBC	O
machine	O
's	O
much	O
more	O
advanced	O
graphics	O
and	O
sound	O
hardware	O
and	O
greater	O
RAM	B-Architecture
capacity	O
.	O
</s>
<s>
Commercial	O
BBC	B-Device
Micro	I-Device
cassettes	O
could	O
not	O
have	O
been	O
loaded	O
anyway	O
,	O
as	O
they	O
ran	O
at	O
a	B-General_Concept
transfer	O
rate	O
of	O
1200	O
baud	O
and	O
the	O
Atom	O
's	O
cassette	O
interface	O
only	O
supported	O
300	O
baud	O
.	O
</s>
<s>
The	O
Acorn	O
LAN	B-General_Concept
,	O
Econet	B-Device
,	O
was	O
first	O
configured	O
on	O
the	O
Atom	O
.	O
</s>
<s>
The	O
Acorn	O
8V	O
power	O
supply	O
was	O
only	O
rated	O
to	O
1.5	O
amps	O
,	O
which	O
was	O
not	O
enough	O
for	O
an	O
Atom	O
with	O
fully	O
populated	O
RAM	B-Architecture
sockets	O
.	O
</s>
<s>
The	O
Atom	O
's	O
two	O
internal	O
LM7805	O
regulators	O
(	O
each	O
regulating	O
the	O
+5V	O
for	O
a	B-General_Concept
section	O
of	O
the	O
digital	O
logic	O
independently	O
)	O
also	O
got	O
uncomfortably	O
hot	O
.	O
</s>
<s>
Three	O
amps	O
were	O
typically	O
needed	O
for	O
a	B-General_Concept
fully	O
populated	O
Atom	O
.	O
</s>
<s>
There	O
has	O
never	O
been	O
a	B-General_Concept
de	O
facto	O
standard	O
for	O
external	O
5V	O
connections	O
,	O
but	O
using	O
the	O
same	O
7-pin	O
DIN	B-Architecture
connectors	I-Architecture
as	O
the	O
Atari	O
800XL	O
allowed	O
an	O
Atari	O
5V	O
linear	O
power	O
supply	O
to	O
drive	O
an	O
Atom	O
,	O
so	O
long	O
as	O
the	O
current	O
was	O
less	O
than	O
the	O
Atari	O
PSU	O
rating	O
(	O
1	O
or	O
1.5	O
amps	O
,	O
depending	O
on	O
the	O
model	O
)	O
.	O
</s>
<s>
These	O
are	O
now	O
uncommon	O
,	O
but	O
5V	O
wall-wart	O
switch-mode	O
power	O
supplies	O
capable	O
of	O
supplying	O
several	O
amps	O
are	O
a	B-General_Concept
readily	O
and	O
cheaply	O
available	O
alternative	O
.	O
</s>
<s>
The	O
Atom	O
was	O
incorporated	O
into	O
a	B-General_Concept
"	O
complete	O
dedicated	O
spreadsheet	O
system	O
"	O
known	O
as	O
the	O
Prophet	O
by	O
a	B-General_Concept
company	O
called	O
Busicomputers	O
,	O
with	O
the	O
second	O
edition	O
of	O
this	O
product	O
,	O
the	O
Prophet	O
2	O
,	O
consisting	O
of	O
a	B-General_Concept
modified	O
Atom	O
,	O
Ferguson	O
12-inch	O
black-and-white	O
television	O
,	O
and	O
a	B-General_Concept
Pearlcorder	O
microcassette	O
recorder	O
,	O
all	O
housed	O
in	O
a	B-General_Concept
"	O
robust	O
metal	O
case	O
"	O
.	O
</s>
<s>
Powered	O
by	O
a	B-General_Concept
single	O
mains	O
plug	O
,	O
the	O
system	O
was	O
effectively	O
a	B-General_Concept
"	O
turnkey	O
"	O
solution	O
,	O
emphasising	O
the	O
built-in	O
spreadsheet	O
as	O
its	O
primary	O
function	O
.	O
</s>
<s>
Although	O
regarded	O
as	O
worth	O
considering	O
as	O
an	O
"	O
inexpensive	O
way	O
of	O
obtaining	O
a	B-General_Concept
sound	O
and	O
reasonably	O
well-presented	O
spreadsheet	O
system	O
"	O
,	O
being	O
priced	O
at	O
£795	O
plus	O
VAT	O
,	O
the	O
use	O
of	O
cassette	O
storage	O
to	O
reduce	O
the	O
system	O
's	O
cost	O
was	O
regarded	O
as	O
impacting	O
its	O
usability	O
,	O
with	O
the	O
slow	O
data	O
transfer	O
rate	O
causing	O
waits	O
of	O
30	O
minutes	O
or	O
more	O
to	O
save	O
spreadsheet	O
data	O
and	O
limiting	O
the	O
effective	O
storage	O
capacity	O
of	O
the	O
microcassettes	O
,	O
whereas	O
more	O
expensive	O
disk-based	O
systems	O
would	O
be	O
able	O
to	O
transfer	O
similar	O
volumes	O
of	O
data	O
in	O
a	B-General_Concept
matter	O
of	O
seconds	O
and	O
store	O
tens	O
of	O
spreadsheets	O
on	O
each	O
disk	O
.	O
</s>
<s>
Regarded	O
as	O
"	O
low-tech	O
"	O
later	O
in	O
1983	O
,	O
the	O
Prophet	O
II	O
was	O
apparently	O
being	O
given	O
away	O
to	O
participants	O
of	O
one	O
-	O
or	O
two-day	O
business-related	O
training	O
courses	O
,	O
these	O
costing	O
£600	O
and	O
£700	O
respectively	O
,	O
with	O
this	O
initiative	O
considered	O
"	O
a	B-General_Concept
nice	O
way	O
of	O
moving	O
old	O
stock	O
"	O
.	O
</s>
<s>
A	B-General_Concept
subsequent	O
model	O
,	O
the	O
Prophet	O
3	O
,	O
featured	O
a	B-General_Concept
built-in	O
floppy	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
