Radio Shack TRS-80 Trsdos & Disk Basic Reference Manual page 8

General
Information
Introduction
This
book
is
a
combined
operation
and
reference
manual
for the
TRS-80
Disk Operating System.
It will
tell
you
how
to
operate
the
hardware and
how
to use the software.
For many
of you,
there
will
be
more
than
enough
information. ("All
I
want
to
do
is
use the
Computer,
not understand
it!")
Don't worry,
this
book
is
designed
so that
you
can
start
programming
in
DISK
BASIC
(if
that's
what you want
to
do)
right
away.
All
you
have
to
do
is
read the chapter
on
Mini Disk Operation
. .
.
skim through
TRSDOS
Overview and
TRSDOS
Commands
...
and on
to
DISK
BASIC.
But
DISK BASIC
is
just
one
aspect of
TRSDOS.
It's
not
a
part
of
TRSDOS,
but
a
program
that
TRSDOS
executes. Using
DISK BASIC
without any awareness of
the
capabilities of
TRSDOS
is
rather
like riding
in a
Pullman
car
without any knowledge
of
the
engine,
freight
cars,
diner
and
other
parts
of
a
train.
It's
true that
TRSDOS
will
do
all
that's
necessary
to let
you
ride
comfortably
along
in
BASIC;
but
eventually you're going to want
to have
a say
in
where
the
train goes,
what
its
schedule
is,
and what
goes
in
all
those
freight
cars.
That's
when you
need
to
understand
TRSDOS.
The
illustration
below shows
the relationship
between
the
Computer,
Expansion
Interface and Mini Disk
Drives.
The
first
drive(Drive
0)
always contains
the
TRSDOS
diskette,
which
is
pre-recorded with the Operating
System
software: an
executive
program, and
several auxiliary
programs, including
DISK
BASIC. The
executive program
is
loaded into the
first
4K
bytes of
RAM,
and
stays there
while
TRSDOS
is
in control.
The
auxiliary programs
are loaded
as
needed.
Second,
third
and
fourth
drives
can contain
diskettes, for storing
your programs and
data.
The Expansion
Interface contains the
real-
time clock, disk controller IC, and
optional
extra
RAM
(addresses above 32767).
The Keyboard/Computer
contains a built-in
(ROM)
program which
takes over
at
power-up, and
loads
the
TRSDOS
executive program from
the
system
diskette
(in
Drive
0).
If the
Mini Disk equipment
is
not connected,
this
ROM
program can
transfer control
to
LEVEL
II
BASIC.
1-2