<s>
The	O
IBM	B-Device
650	I-Device
Magnetic	B-General_Concept
Drum	I-General_Concept
Data-Processing	O
Machine	O
is	O
an	O
early	O
digital	O
computer	O
produced	O
by	O
IBM	O
in	O
the	O
mid-1950s	O
.	O
</s>
<s>
The	O
650	O
was	O
marketed	O
to	O
business	O
,	O
scientific	O
and	O
engineering	O
users	O
as	O
a	O
general-purpose	O
version	O
of	O
the	O
IBM	B-Device
701	I-Device
and	O
IBM	B-Device
702	I-Device
computers	O
which	O
were	O
for	O
scientific	O
and	O
business	O
purposes	O
respectively	O
.	O
</s>
<s>
It	O
was	O
also	O
marketed	O
to	O
users	O
of	O
punched	O
card	O
machines	O
who	O
were	O
upgrading	O
from	O
calculating	O
punches	O
,	O
such	O
as	O
the	O
IBM	B-Device
604	I-Device
,	O
to	O
computers	O
.	O
</s>
<s>
Because	O
of	O
its	O
relatively	O
low	O
cost	O
and	O
ease	O
of	O
programming	B-General_Concept
,	O
the	O
650	O
was	O
used	O
to	O
pioneer	O
a	O
wide	O
variety	O
of	O
applications	O
,	O
from	O
modeling	O
submarine	O
crew	O
performance	O
to	O
teaching	O
high	O
school	O
and	O
college	O
students	O
computer	B-General_Concept
programming	I-General_Concept
.	O
</s>
<s>
The	O
IBM	B-Device
650	I-Device
became	O
highly	O
popular	O
in	O
universities	O
,	O
where	O
a	O
generation	O
of	O
students	O
first	O
learned	O
programming	B-General_Concept
.	O
</s>
<s>
It	O
was	O
announced	O
in	O
1953	O
and	O
in	O
1956	O
enhanced	O
as	O
the	O
IBM	B-Device
650	I-Device
RAMAC	O
with	O
the	O
addition	O
of	O
up	O
to	O
four	O
disk	O
storage	O
units	O
.	O
</s>
<s>
The	O
650	O
was	O
a	O
two-address	B-General_Concept
,	O
bi-quinary	B-Algorithm
coded	I-Algorithm
decimal	I-Algorithm
computer	O
(	O
both	O
data	O
and	O
addresses	O
were	O
decimal	O
)	O
,	O
with	O
memory	B-General_Concept
on	O
a	O
rotating	O
magnetic	B-General_Concept
drum	I-General_Concept
.	O
</s>
<s>
Character	O
support	O
was	O
provided	O
by	O
the	O
input/output	O
units	O
converting	O
punched	O
card	O
alphabetical	O
and	O
special	O
character	B-General_Concept
encodings	I-General_Concept
to/from	O
a	O
two-digit	O
decimal	O
code	O
.	O
</s>
<s>
The	O
IBM	B-Device
7070	I-Device
(	O
signed	O
10-digit	O
decimal	O
words	O
)	O
,	O
announced	O
1958	O
,	O
was	O
expected	O
to	O
be	O
a	O
"	O
common	O
successor	O
to	O
at	O
least	O
the	O
650	O
and	O
the	O
 [ IBM ] 	B-Device
705	I-Device
"	O
.	O
</s>
<s>
The	O
IBM	B-Device
1620	I-Device
(	O
variable-length	O
decimal	O
)	O
,	O
introduced	O
in	O
1959	O
,	O
addressed	O
the	O
lower	O
end	O
of	O
the	O
market	O
.	O
</s>
<s>
The	B-Operating_System
UNIVAC	I-Operating_System
Solid	O
State	O
(	O
a	O
two-address	B-General_Concept
computer	O
,	O
signed	O
10-digit	O
decimal	O
words	O
)	O
was	O
announced	O
by	O
Sperry	O
Rand	O
in	O
December	O
1958	O
as	O
a	O
response	O
to	O
the	O
650	O
.	O
</s>
<s>
None	O
of	O
these	O
had	O
an	O
instruction	B-General_Concept
set	I-General_Concept
that	O
was	O
compatible	O
with	O
the	O
650	O
.	O
</s>
<s>
IBM	B-Device
650	I-Device
Console	O
Unit	O
housed	O
the	O
magnetic	B-General_Concept
drum	I-General_Concept
storage	O
,	O
arithmetical	O
device	O
(	O
using	O
vacuum	O
tubes	O
)	O
and	O
the	O
operator	O
's	O
console	O
.	O
</s>
<s>
IBM	B-Device
533	I-Device
or	O
IBM	O
537	O
Card	O
Read	O
Punch	O
Unit	O
The	O
IBM	B-Device
533	I-Device
had	O
separate	O
feeds	O
for	O
reading	O
and	O
punching	O
;	O
the	O
IBM	O
537	O
had	O
one	O
feed	O
,	O
thus	O
could	O
read	O
and	O
then	O
punch	O
into	O
the	O
same	O
card	O
.	O
</s>
<s>
Rotating	O
drum	B-General_Concept
memory	I-General_Concept
provided	O
1	O
,	O
000	O
,	O
2	O
,	O
000	O
,	O
or	O
4,000	O
words	O
of	O
memory	B-General_Concept
at	O
addresses	O
0000	O
to	O
0999	O
,	O
1999	O
,	O
or	O
3999	O
respectively	O
.	O
</s>
<s>
Each	O
word	O
had	O
10	O
bi-quinary	B-Algorithm
coded	I-Algorithm
decimal	I-Algorithm
digits	O
,	O
representing	O
a	O
signed	O
10-digit	O
number	O
or	O
five	O
characters	O
.	O
</s>
<s>
(	O
Counting	O
a	O
bi-quinary	B-Algorithm
coded	O
digit	O
as	O
7	O
bits	O
,	O
4000	O
words	O
would	O
be	O
equivalent	O
to	O
35	O
kilobytes	O
.	O
)	O
</s>
<s>
Words	O
on	O
the	O
drums	O
were	O
organized	O
in	O
bands	O
around	O
the	O
drum	B-General_Concept
,	O
fifty	O
words	O
per	O
band	O
,	O
and	O
20	O
,	O
40	O
,	O
or	O
80	O
bands	O
for	O
the	O
respective	O
models	O
.	O
</s>
<s>
A	O
word	O
could	O
be	O
accessed	O
when	O
its	O
location	O
on	O
the	O
drum	B-General_Concept
surface	O
passed	O
under	O
the	O
read/write	O
heads	O
during	O
rotation	O
(	O
rotating	O
at	O
12,500	O
rpm	O
,	O
the	O
non-optimized	O
average	O
access	O
time	O
was	O
2.5	O
ms	O
)	O
.	O
</s>
<s>
Programs	O
could	O
then	O
be	O
optimized	O
by	O
placing	O
instructions	B-General_Concept
at	O
addresses	O
that	O
would	O
be	O
immediately	O
accessible	O
when	O
execution	O
of	O
the	O
previous	O
instruction	O
was	O
completed	O
.	O
</s>
<s>
IBM	O
provided	O
a	O
form	O
with	O
ten	O
columns	O
and	O
200	O
rows	O
to	O
allow	O
programmers	O
to	O
keep	O
track	O
of	O
where	O
they	O
put	O
instructions	B-General_Concept
and	O
data	O
.	O
</s>
<s>
Later	O
an	O
assembler	B-Application
,	O
SOAP	O
(	O
Symbolic	B-Application
Optimal	I-Application
Assembly	I-Application
Program	I-Application
)	O
,	O
was	O
provided	O
that	O
performed	O
rough	O
optimization	O
.	O
</s>
<s>
The	O
LGP-30	B-Device
,	O
Bendix	B-Device
G-15	I-Device
and	O
IBM	B-Device
305	I-Device
RAMAC	I-Device
computers	O
used	O
vacuum	O
tubes	O
and	O
drum	B-General_Concept
memory	I-General_Concept
,	O
too	O
,	O
but	O
they	O
were	O
quite	O
different	O
from	O
the	O
IBM	B-Device
650	I-Device
.	O
</s>
<s>
Instructions	B-General_Concept
read	O
from	O
the	O
drum	B-General_Concept
went	O
to	O
a	O
program	O
register	O
(	O
in	O
current	O
terminology	O
,	O
an	O
instruction	B-General_Concept
register	I-General_Concept
)	O
.	O
</s>
<s>
Data	O
read	O
from	O
the	O
drum	B-General_Concept
went	O
through	O
a	O
10-digit	O
distributor	O
.	O
</s>
<s>
The	O
650	O
had	O
a	O
20-digit	O
accumulator	B-General_Concept
,	O
divided	O
into	O
10-digit	O
lower	O
and	O
upper	O
accumulators	B-General_Concept
with	O
a	O
common	O
sign	O
.	O
</s>
<s>
The	O
console	O
(	O
10	O
digit	O
switches	O
,	O
one	O
sign	O
switch	O
,	O
and	O
10	O
bi-quinary	B-Algorithm
display	O
lights	O
)	O
,	O
distributor	O
,	O
lower	O
and	O
upper	O
accumulators	B-General_Concept
were	O
all	O
addressable	O
;	O
8000	O
,	O
8001	O
,	O
8002	O
,	O
8003	O
respectively	O
.	O
</s>
<s>
Sixty	O
10-digit	O
words	O
of	O
magnetic	B-General_Concept
core	I-General_Concept
memory	B-General_Concept
at	O
addresses	O
9000	O
to	O
9059	O
;	O
a	O
small	O
fast	O
memory	B-General_Concept
(	O
this	O
device	O
gave	O
a	O
memory	B-General_Concept
access	O
time	O
of	O
96µs	O
,	O
a	O
26-fold	O
raw	O
improvement	O
relative	O
to	O
the	O
rotating	O
drum	B-General_Concept
)	O
,	O
needed	O
for	O
a	O
tape	O
and	O
disk	O
I/O	O
buffer	O
.	O
</s>
<s>
Three	O
four-digit	O
index	B-General_Concept
registers	I-General_Concept
at	O
addresses	O
8005	O
to	O
8007	O
;	O
drum	B-General_Concept
addresses	O
were	O
indexed	O
by	O
adding	O
2000	O
,	O
4000	O
or	O
6000	O
to	O
them	O
,	O
core	O
addresses	O
were	O
indexed	O
by	O
adding	O
0200	O
,	O
0400	O
or	O
0600	O
to	O
them	O
.	O
</s>
<s>
If	O
the	O
system	O
had	O
the	O
4000	O
word	O
drum	B-General_Concept
then	O
indexing	O
was	O
by	O
adding	O
4000	O
to	O
the	O
first	O
address	O
for	O
index	B-General_Concept
register	I-General_Concept
A	O
,	O
adding	O
4000	O
to	O
the	O
second	O
address	O
for	O
index	B-General_Concept
register	I-General_Concept
B	O
,	O
and	O
by	O
adding	O
4000	O
to	O
each	O
of	O
the	O
two	O
addresses	O
for	O
index	B-General_Concept
register	I-General_Concept
C	O
(	O
the	O
indexing	O
for	O
4000-word	O
systems	O
only	O
applied	O
to	O
the	O
first	O
address	O
)	O
.	O
</s>
<s>
The	O
4000-word	O
systems	O
required	O
transistorized	B-Device
read/write	O
circuitry	O
for	O
the	O
drum	B-General_Concept
memory	I-General_Concept
and	O
were	O
available	O
before	O
1963	O
.	O
</s>
<s>
Floating	B-Algorithm
point	I-Algorithm
–	O
arithmetic	O
instructions	B-General_Concept
supported	O
an	O
eight-digit	O
mantissa	O
and	O
two-digit	O
characteristic	O
(	O
offset	O
exponent	O
)	O
–	O
MMMMMMMMCC	O
,	O
providing	O
a	O
range	O
of	O
±	O
0.00000001E-50	O
to	O
±	O
0.99999999E	O
+49	O
.	O
</s>
<s>
The	O
650	O
instructions	B-General_Concept
consisted	O
of	O
a	O
two-digit	O
operation	B-Language
code	I-Language
,	O
a	O
four-digit	O
data	O
address	O
and	O
the	O
four-digit	O
address	O
of	O
the	O
next	O
instruction	O
.	O
</s>
<s>
The	O
base	O
machine	O
had	O
44	O
operation	B-Language
codes	I-Language
.	O
</s>
<s>
Additional	O
operation	B-Language
codes	I-Language
were	O
provided	O
for	O
options	O
,	O
such	O
as	O
floating	B-Algorithm
point	I-Algorithm
,	O
core	O
storage	O
,	O
index	B-General_Concept
registers	I-General_Concept
and	O
additional	O
I/O	O
devices	O
.	O
</s>
<s>
With	O
all	O
options	O
installed	O
,	O
there	O
were	O
97	O
operation	B-Language
codes	I-Language
.	O
</s>
<s>
The	O
Table	O
lookup	O
(	O
TLU	O
)	O
instruction	O
could	O
high-equal	O
compare	O
a	O
referenced	O
10-digit	O
word	O
with	O
48	O
consecutive	O
words	O
on	O
the	O
same	O
drum	B-General_Concept
band	O
in	O
one	O
5ms	O
revolution	O
and	O
then	O
switch	O
to	O
the	O
next	O
band	O
in	O
time	O
for	O
the	O
next	O
48	O
words	O
.	O
</s>
<s>
This	O
feat	O
was	O
about	O
one-third	O
the	O
speed	O
of	O
a	O
one-thousand	O
times	O
faster	O
binary	O
machine	O
in	O
1963	O
(	O
1,500	O
microseconds	O
on	O
the	O
IBM	O
7040	O
to	O
5,000	O
microseconds	O
on	O
the	O
650	O
)	O
for	O
looking	O
up	O
46	O
entries	O
as	O
long	O
as	O
both	O
were	O
programmed	O
in	O
assembler	B-Application
.	O
</s>
<s>
The	O
Read	O
(	O
RD	O
)	O
instruction	O
read	O
an	O
80	O
column	O
card	O
of	O
numeric	B-Algorithm
data	O
into	O
ten	O
memory	B-General_Concept
words	O
;	O
the	O
distribution	O
of	O
digits	O
to	O
words	O
determined	O
by	O
the	O
card	O
reader	O
's	O
control	O
panel	O
wiring	O
.	O
</s>
<s>
When	O
used	O
with	O
the	O
533	O
Reader	O
Punch	O
unit	O
's	O
Alphabetic	O
device	O
,	O
a	O
combination	O
of	O
numeric	B-Algorithm
and	O
alphanumeric	O
columns	O
(	O
maximum	O
of	O
30	O
alphanumeric	O
columns	O
)	O
could	O
be	O
read	O
.	O
</s>
<s>
An	O
expansion	O
feature	O
allowed	O
more	O
alphanumeric	O
columns	O
but	O
certainly	O
not	O
over	O
50	O
,	O
as	O
only	O
ten	O
words	O
(	O
five	O
characters	O
per	O
word	O
)	O
were	O
stored	O
on	O
the	O
drum	B-General_Concept
by	O
a	O
card	O
read	O
operation	O
.	O
</s>
<s>
The	O
base	O
machine	O
operation	B-Language
codes	I-Language
were	O
:	O
</s>
<s>
The	O
IBM	O
653	O
options	O
could	O
implement	O
additional	O
instruction	B-Language
codes	I-Language
.	O
</s>
<s>
This	O
one-card	O
program	O
,	O
taken	O
from	O
the	O
650	O
Programming	B-General_Concept
Bulletin	O
5	O
,	O
IBM	O
,	O
1956	O
,	O
22-6314-0	O
,	O
will	O
set	O
most	O
of	O
the	O
drum	B-General_Concept
storage	I-General_Concept
to	O
minus	O
zeros	O
.	O
</s>
<s>
The	O
program	O
includes	O
examples	O
of	O
instructions	B-General_Concept
being	O
executed	O
from	O
the	O
console	O
switches	O
and	O
from	O
an	O
accumulator	B-General_Concept
.	O
</s>
<s>
To	O
begin	O
,	O
a	O
load	O
card	O
is	O
keypunched	O
with	O
80	O
consecutive	O
digits	O
(	O
the	O
second	O
column	O
below	O
)	O
so	O
that	O
,	O
when	O
read	O
,	O
drum	B-General_Concept
locations	O
0001	O
through	O
0008	O
contents	O
will	O
be	O
as	O
shown	O
.	O
</s>
<s>
Each	O
drum	B-General_Concept
band	O
has	O
a	O
read	O
area	O
;	O
these	O
read	O
areas	O
are	O
in	O
locations	O
0001-0010	O
,	O
0051-0060	O
,	O
0101-0110	O
and	O
so	O
on	O
.	O
</s>
<s>
Execution	O
begins	O
then	O
,	O
from	O
the	O
console	O
with	O
the	O
reading	O
of	O
the	O
eight	O
words	O
on	O
the	O
load	O
card	O
into	O
locations	O
0001-0008	O
of	O
the	O
first	O
memory	B-General_Concept
band	O
.	O
</s>
<s>
requires	O
two	O
instructions	B-General_Concept
:	O
LD	O
,	O
STD	O
.	O
</s>
<s>
This	O
instruction	O
was	O
placed	O
in	O
the	O
upper	O
accumulator	B-General_Concept
by	O
the	O
RSU	O
instruction	O
above	O
.	O
</s>
<s>
executed	O
again	O
while	O
still	O
in	O
the	O
accumulator	B-General_Concept
.	O
</s>
<s>
Donald	O
Knuth	O
's	O
series	O
of	O
books	O
The	B-General_Concept
Art	I-General_Concept
of	I-General_Concept
Computer	I-General_Concept
Programming	I-General_Concept
is	O
famously	O
dedicated	O
to	O
a	O
650	O
.	O
</s>
<s>
Software	O
written	O
for	O
the	O
IBM	B-Device
650	I-Device
included	O
:	O
</s>
<s>
Technical	O
Assembly	O
System	O
(	O
TASS	O
)	O
—	O
A	O
macro	B-Language
assembler	I-Language
.	O
</s>
<s>
An	O
Interpretive	O
application	O
virtual	O
machine	O
package	O
originally	O
published	O
as	O
"	O
Complete	O
Floating	O
Decimal	O
Interpretive	O
System	O
for	O
the	O
IBM	B-Device
650	I-Device
Magnetic	B-General_Concept
Drum	I-General_Concept
Calculator	O
"	O
.	O
</s>
<s>
IPL	B-Language
—	O
The	O
first	O
list	O
processing	O
language	O
.	O
</s>
<s>
The	O
best-known	O
version	O
was	O
IPL-V	B-Language
.	O
</s>
