VECTOR 4 USER'S
MANUAL
INTRODUCTION TO VECTOR 4 CP/M
But to load from disk into
the
TP
A,
the
operating system mus t
firs
t
find
ou t
where
to
look
on
the
disk,
and
then
copy into
the
Transient Program Area.
To do
this,
it
uses
the
other
two
functions
of
the
system.
The
Basic
Input/Output
System
(BIOS)
acts
like
the
switchboard operator, opening lines
between disk and TPA so
that
the
program
can
be
copied.
Then
the
Basic
Disk
Operating
System
(BOOS)
"reads"
the
directory
of programs, finds
the
desired information on
the
disk, and sends a copy over the lines opened by
the
BIOS.
Review
The
Console
Command
Processor
interprets
user
commands and
either
works
from
its
own instructions (in
the
case
of
resjdent commands), or calls programs
from mass memory (in
the
case
of
transient
commands.)
The
Transient
Proiram
Area
stores
and
runs
programs
called
by
user
commands.
The
Basic
Di~k
OperatiIli System keeps
track
of
all
the
data
as
the
operating
system sends
it
off
to
storage,
or
pulls
it
from mass memory into
the
RAM.
The
Basic
Im)UtlOutput
System
controls
the
circuits
to
be
used
for
all
transfer,
turning
the
hardware on and
off
when required.
How
Does
The
System
Get
Started!
Recall
from
the
discussion
of
volatile
memory
that
the
RAM
will only hold
information while
it
is supplied with
electrical
current.
While
the
computer
is
turned
off,
the
operating system is
stored
on disk. These instructions must be
copied from
the
disk
into
the
RAM,
where
they
can
control
the
computer.
But
if
the
power
has
been
turned
off,
the
RAM
is "emptied" and must be
"refilled" from
the
disk.
Once
the
system
is
operating,
loading
a
program
would be a simple task:
the
Basic Disk Operating System
(BOOS)
would look up
the right files on
the
disk and copy them into volatile memory. But the
BOOS
itself
hasn't
been copied into memory
yet.
Let's
compare this to a
stereo.
The music is always on the record, whether
it
is
in
the
store,
in its
jacket,
or on
the
turntable. But
the
music
can
only
get
from the grooves of
the
record,
out
the speakers, and into your ears when you
have
the
power switch turned on.
And
even then,
there
are
actions you must
take: position
the
tone arm over the song you
want
to
hear,
set
the
volume
and speed control, adjust
the
balance between
the
speakers, and maybe more if
you have a complex system. But if you
turn
the power
off,
the
music
stops.
It
just
goes away.
Rev. A -
9-01-82
7100-0001
vn-9
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