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Your KB—490O is a
product
of the
computer
age.
Unlike its
predecessors
the KB—42OO AND
KB-4800,
this unit does not use discrete dedicated
parts
to
perform
its function.
Instead,
it
employs
an
"all
purpose"
IC called an
integrated microprocessor.
This
device
does
nothing
itself,
however,
when
provided
with a
list of
instructions,
it will
carry
them
out
and in so
doing,
accomplish
the
objectives
of the
programmer
who devised the set of instruct‘
ions.
The KB—4900 uses a
microprocessor
called the 5035
(developed by
the
Intel
Corporation).
The 9035 contains an 8-bit
central
processor
unit
(CPU),
512 bits of
random access
memory
(RAM),
27
input—output
lines (1/0) and
an B~bit timer/event
counter.
For
instructions,
we use the
2732 (Ultra-Violet) Eraseable
Programmable
Read—Dn1y Memory
(EPRDH). It can
contain
as
many
as
4,096
individual
instructions
composed
of
32,768
individual bits. The
sending
buffer and
message storage
are
implemented
in another
powerful
IC,
the 2114. This
Random—Access
Memory
(RAM) will
store
512
Esbit
bytes
in its
4,096
read‘
write
storage cells,
and
last,
but not
least,
the
venerable 9044
single
chip
keyer
IC
provides
the Morse
code
generation
in
order to free the
processor
for more
complicated
tasks. For
those
of
you
interested in
statistics,
the
circuitry
in
the KB—4900 contains
approximately
100,000
individual
transistors.
The
program
for
the KB—4900 uses most
of the
4,096
instructions
possible
from the
2732. From
a
library
of 90
individual instructions
recognized by
the
microprocessor,
the
program
is
built-up
into
a
sequence
that
provides
the
function of
the KB—4900.
The
microprocessor
winds its
way through
the
program
at the
rate of
400,000
instructions
per
second.
And,
while it looks
as
though
things
are
being
done all at
once,
in
reality they
are
being
done
one—by—one.
The
processor
does
everything serially except
that it handles
all data in
groups
of
eight binary digits
called
bytes.
The
processor
is
unbelievably busy
while the
unit is
operation,
executing
the
prescribed
program
at the 400 KHZ
rate. It is not
unlike a
juggler
keeping
many plates
spinning
at
one time.
Though
we have
only
one
juggler,
there is a whole
lot of
activity
going
on. In the
case of the
KB«4900,
it
may
be
sending
DU,
accepting
new
key
inputs,
assigning spaces
in
the
sending buffer, unloading
the
sending
buffer at
some other
point, running
the buffer
meter, running
the
speed
meter,
holding
the
PTT line
down,
watching
for buffer
overflow, keeping
track of the
time.
incrementing
the serial
number,
and
scanning
the
keyboard
for new
commands....400,000
times a
second without mistakes!
The
program
for
the KB—4900
consists of 78
pages
of
single spaced
text. It
took
nearly
six
months
of
writing,
testing
and
debugging
to
get
the
program ready.
we
hope you
enjoy using
the
system
as much
as
we
enjoyed
designing
it,
If
you
have
suggestions
on how we
might
improve
the
unit,
don’t
hesitate to
call or
drop
a line.
(D
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