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Appendix B -
Summary of 1620 Operating Principles
Typewriter Input
Th
e
typewriter
IS
part
of
the
1620
console and
is
used
for both input
and output.
Input
The
typewriter
is
used to
enter both
data and
instruc-
tions direc tly
into
cor
storage. Press ing the console
insert
key unlocks the
keyboard and
permits data to
be
ent
red
into core
storage starting
at
locati on
00000.
Each depression
of a
typewriter
key enters
th
e
char-
acter into core
storage
one
loca
tion hi
gher
than the
previous
character. As
many
as 100
cha racters can
be
entered from
the
typewriter.
After
th
e
100th
character
is
entered,
an automatic
release is
initiated
and
th
e
machine returns to manual
mode.
Figure
1.
IBM
1620
I/O
Typewriter
When
I
ss
than 100
characters
are entered,
entry
of
the
last
desired
character
should
be
followed by
press-
ing the console release
and
start
keys,
or
by pressin
g
th R-S
key
on
the
typewriter
keyboard.
The
R-S
key
combines the release
and start
functions of
the
console
keys. The
R-S symbol is
typed as a
permanent record
tha
t
the
R-S
key
has been used.
Programm
ed
selection
of
th
e
typewriter
unlocks
the
keyboard
and
leaves the
computer
in
automatic
mode
for manual
entry
of
data
on
th
e
typewriter. Data
entry
starts
at
th
e
addressed
location
(
P
address) of
the in-
struction and
enters
core
storage
at
successively
hi
gher-
order
positions until
the release key is
depressed.
If
a
record
mark
is req
uired in
core
storage
followin
g
the
last
character
entered,
the
record mark
key
on
the
typewriter
mll st
be
pressed befor
press ing
th
e release
key
on
the
console.
Appendix B
83
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