<s>
TRSDOS	B-Operating_System
(	O
which	O
stands	O
for	O
the	O
Tandy	O
Radio	O
Shack	O
Disk	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
)	O
is	O
the	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
Tandy	B-Device
TRS-80	I-Device
line	O
of	O
eight-bit	O
Zilog	B-General_Concept
Z80	I-General_Concept
microcomputers	O
that	O
were	O
sold	O
through	O
Radio	O
Shack	O
from	O
1977	O
through	O
1991	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
should	O
not	O
be	O
confused	O
with	O
Tandy	O
DOS	B-Device
,	O
a	O
version	O
of	O
MS-DOS	B-Application
licensed	O
from	O
Microsoft	O
for	O
Tandy	O
's	O
x86	B-Operating_System
line	O
of	O
personal	B-Device
computers	I-Device
(	O
PCs	B-Device
)	O
.	O
</s>
<s>
With	O
the	O
original	O
TRS-80	B-Device
Model	I-Device
I	I-Device
of	O
1977	O
,	O
TRSDOS	B-Operating_System
was	O
primarily	O
a	O
way	O
of	O
extending	O
the	O
MBASIC	O
(	O
BASIC	O
in	O
ROM	B-Device
)	O
with	O
additional	O
I/O	B-General_Concept
(	O
input/output	B-General_Concept
)	O
commands	O
that	O
worked	O
with	O
disk	O
files	O
rather	O
than	O
the	O
cassette	O
tapes	O
that	O
were	O
used	O
by	O
non-disk	O
Model	O
I	O
systems	O
.	O
</s>
<s>
Later	O
disk-equipped	O
Model	O
III	O
computers	O
used	O
a	O
completely	O
different	O
version	O
of	O
TRSDOS	B-Operating_System
by	O
Radio	O
Shack	O
which	O
culminated	O
in	O
1981	O
with	O
TRSDOS	B-Operating_System
Version	O
1.3	O
.	O
</s>
<s>
From	O
1983	O
disk-equipped	O
TRS-80	B-Device
Model	I-Device
4	I-Device
computers	O
used	O
TRSDOS	B-Operating_System
Version	O
6	O
,	O
which	O
was	O
a	O
development	O
of	O
Model	O
III	O
LDOS	B-Operating_System
by	O
Logical	O
Systems	O
,	O
Inc	O
.	O
</s>
<s>
This	O
last	O
was	O
updated	O
in	O
1987	O
and	O
released	O
as	O
LS-DOS	O
6.3	O
.	O
</s>
<s>
Completely	O
unrelated	O
was	O
a	O
version	O
of	O
TRSDOS	B-Operating_System
by	O
Radio	O
Shack	O
for	O
its	O
TRS-80	B-Device
Model	I-Device
II	I-Device
professional	O
computer	O
from	O
1979	O
,	O
also	O
based	O
on	O
the	O
Z80	B-General_Concept
and	O
equipped	O
with	O
8-inch	O
disk	O
drives	O
.	O
</s>
<s>
The	O
later	O
machines	O
in	O
this	O
line	O
,	O
the	O
Models	O
12	O
,	O
16	O
and	O
6000	O
,	O
used	O
the	O
Z80	B-General_Concept
as	I-General_Concept
an	O
alternate	O
CPU	O
to	O
its	O
main	O
Motorola	B-Device
68000	I-Device
chip	O
and	O
could	O
run	O
this	O
version	O
of	O
TRSDOS	B-Operating_System
for	O
backwards	O
compatibility	O
with	O
older	O
Z80	B-General_Concept
applications	O
software	O
.	O
</s>
<s>
Tandy	O
Corporation	O
's	O
TRS-80	B-Device
microcomputer	O
did	O
not	O
have	O
a	O
disk	O
drive	O
or	O
disk	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
at	O
release	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
TRSDOS	B-Operating_System
,	O
by	O
Randy	O
Cook	O
,	O
was	O
so	O
buggy	O
that	O
others	O
wrote	O
alternatives	O
,	O
including	O
NewDOS	B-Operating_System
and	O
LDOS	B-Operating_System
.	O
</s>
<s>
After	O
disputes	O
with	O
Cook	O
over	O
ownership	O
of	O
the	O
source	O
code	O
,	O
Tandy	O
hired	O
Logical	O
Systems	O
,	O
LDOS	B-Operating_System
's	O
developer	O
,	O
to	O
continue	O
TRSDOS	B-Operating_System
development	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
6	O
,	O
shipped	O
with	O
the	O
TRS-80	B-Device
Model	I-Device
4	I-Device
in	O
1983	O
,	O
is	O
identical	O
to	O
LDOS	B-Operating_System
6.00	O
.	O
</s>
<s>
Late	O
1986	O
–	O
Logical	O
Systems	O
releases	O
LS-DOS	O
6.3	O
,	O
the	O
functionally	O
equivalent	O
update	O
to	O
TRSDOS	B-Operating_System
6.2	O
.	O
</s>
<s>
RadioShack	O
's	O
Z80-based	O
line	O
of	O
TRS-80	B-Device
computers	O
(	O
Models	B-Device
I/III	I-Device
and	O
Model	B-Device
4	I-Device
)	O
support	O
up	O
to	O
four	O
physical	O
floppy	B-Device
(	O
mini-diskette	O
)	O
drives	O
which	O
(	O
as	O
sold	O
)	O
use	O
5¼-inch	B-Device
diskettes	I-Device
.	O
</s>
<s>
The	O
original	O
TRSDOS	B-Operating_System
for	O
the	O
Model	O
I	O
supported	O
only	O
single-sided	O
disks	O
with	O
35	O
tracks	O
formatted	O
in	O
single	O
density	O
(	O
sectors	O
are	O
encoded	O
using	O
the	O
frequency	B-Application
modulation	I-Application
technique	O
)	O
.	O
</s>
<s>
Model	O
III	O
TRSDOS	B-Operating_System
(	O
culminating	O
in	O
version	O
1.3	O
)	O
supported	O
40-track	O
disks	O
formatted	O
in	O
double	O
density	O
(	O
using	O
modified	B-Protocol
frequency	I-Protocol
modulation	I-Protocol
)	O
.	O
</s>
<s>
Model	O
Is	O
retrofitted	O
with	O
double	O
density	O
controllers	O
and	O
Models	B-Device
I/III	I-Device
equipped	O
with	O
80-track	O
drives	O
or	O
double-sided	O
drives	O
could	O
not	O
use	O
TRSDOS	B-Operating_System
;	O
RadioShack	O
sold	O
Logical	O
System	O
's	O
LDOS	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
which	O
could	O
control	O
these	O
types	O
of	O
drives	O
.	O
</s>
<s>
The	O
Model	B-Device
4	I-Device
's	O
TRSDOS	B-Operating_System
6	O
is	O
a	O
development	O
of	O
LDOS	B-Operating_System
and	O
has	O
the	O
same	O
capabilities	O
.	O
</s>
<s>
These	O
drivers	O
permitted	O
any	O
TRSDOS	B-Operating_System
installation	O
to	O
access	O
them	O
with	O
up	O
to	O
eight	O
possible	O
drive	O
partitions	O
,	O
each	O
assigned	O
to	O
drive	O
numbers	O
zero	O
through	O
seven	O
.	O
</s>
<s>
Actually	O
,	O
a	O
large	O
hard	O
drive	O
could	O
be	O
formatted	O
with	O
more	O
than	O
eight	O
partitions	O
,	O
but	O
TRSDOS	B-Operating_System
can	O
only	O
access	O
eight	O
during	O
any	O
one	O
session	O
.	O
</s>
<s>
Hard	O
drives	O
could	O
have	O
some	O
partitions	O
formatted	O
under	O
TRSDOS	B-Operating_System
and	O
others	O
under	O
the	O
CP/M	B-Application
OS	O
.	O
</s>
<s>
Each	O
floppy	B-Device
drive	I-Device
in	O
the	O
system	O
would	O
also	O
take	O
up	O
one	O
drive	O
number	O
assignment	O
.	O
</s>
<s>
The	O
Model	B-Device
4	I-Device
,	O
with	O
its	O
ability	O
to	O
set	O
up	O
a	O
ramdisk	B-Application
(	O
Memdisk	O
)	O
,	O
also	O
required	O
a	O
drive	O
number	O
assignment	O
for	O
this	O
.	O
</s>
<s>
All	O
versions	O
of	O
TRSDOS	B-Operating_System
use	O
overlays	O
to	O
satisfy	O
most	O
system	O
requests	O
and	O
disk	O
directories	O
are	O
not	O
maintained	O
in	O
memory	O
.	O
</s>
<s>
First	O
,	O
upon	O
initial	O
file	O
access	O
the	O
DOS	B-Device
always	O
references	O
the	O
disk	O
directory	O
to	O
obtain	O
information	O
giving	O
the	O
physical	O
mapping	O
of	O
disk	O
space	O
allocated	O
to	O
the	O
file	O
(	O
including	O
its	O
extents	O
,	O
if	O
any	O
)	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
has	O
commands	O
permitting	O
the	O
user	O
to	O
optimize	O
placement	O
of	O
particular	O
files	O
on	O
the	O
disk	O
's	O
physical	O
space	O
,	O
and	O
the	O
command	O
to	O
display	O
a	O
map	O
of	O
a	O
file	O
's	O
physical	O
placement	O
on	O
a	O
drive	O
.	O
</s>
<s>
The	O
second	O
implication	O
of	O
the	O
overlay-based	O
architecture	O
is	O
that	O
a	O
disk	O
containing	O
TRSDOS	B-Operating_System
system	O
files	O
(	O
file	O
extension	O
/SYS	O
)	O
must	O
always	O
be	O
present	O
in	O
whichever	O
drive	O
is	O
assigned	O
as	O
logical	O
drive	O
number	O
zero	O
.	O
</s>
<s>
(	O
On	O
the	O
Model	B-Device
4	I-Device
this	O
may	O
be	O
the	O
Memdisk	O
,	O
thus	O
freeing	O
physical	O
drive	O
zero	O
be	O
used	O
for	O
a	O
non-system	O
data	O
disk	O
)	O
.	O
</s>
<s>
LDOS	B-Operating_System
and	O
TRSDOS	B-Operating_System
6	O
have	O
a	O
SYSRES	O
command	O
which	O
loads	O
selected	O
system	O
files	O
into	O
Z80	B-General_Concept
RAM	O
,	O
thus	O
freeing	O
space	O
on	O
the	O
system	O
disk	O
for	O
non-system	O
data	O
.	O
</s>
<s>
Drives	O
may	O
be	O
set	O
to	O
be	O
write	O
protected	O
by	O
the	O
DOS	B-Device
,	O
also	O
.	O
</s>
<s>
The	O
primary	O
function	O
of	O
any	O
disk	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
is	O
to	O
provide	O
the	O
user	O
with	O
a	O
facility	O
for	O
managing	O
and	O
accessing	O
files	O
stored	O
on	O
disk	O
storage	O
devices	O
.	O
</s>
<s>
Since	O
the	O
user	O
must	O
not	O
be	O
burdened	O
with	O
the	O
physical	O
details	O
of	O
the	O
storage	O
devices	O
themselves	O
,	O
it	O
is	O
the	O
operating	B-General_Concept
system	I-General_Concept
's	O
responsibility	O
to	O
translate	O
file	O
record	O
access	O
requests	O
into	O
specific	O
drive	O
,	O
track	O
,	O
sector	O
,	O
and	O
head	O
parameters	O
that	O
pinpoint	O
the	O
storage	O
location	O
of	O
each	O
record	O
.	O
</s>
<s>
The	O
system	O
also	O
maintains	O
in	O
Z80	B-General_Concept
memory	O
within	O
TRSDOS	B-Operating_System
a	O
Drive	O
Control	O
Table	O
that	O
stores	O
the	O
parameters	O
associated	O
with	O
each	O
of	O
the	O
eight	O
logical	O
drives	O
.	O
</s>
<s>
The	O
layer(s )	O
of	O
magnetic	O
particles	O
on	O
the	O
surface	O
of	O
the	O
disk	O
media	O
are	O
magnetized	O
(	O
during	O
the	O
format	B-Application
process	O
)	O
into	O
concentric	O
circles	O
of	O
storage	O
areas	O
called	O
TRACKS	O
.	O
</s>
<s>
Although	O
the	O
number	O
of	O
sectors	O
per	O
track	O
may	O
vary	O
from	O
one	O
media	O
type	B-Device
to	O
another	O
,	O
the	O
number	O
of	O
sectors	O
in	O
each	O
track	O
of	O
the	O
same	O
media	O
(	O
and	O
in	O
each	O
granule	O
)	O
must	O
always	O
be	O
a	O
constant	O
.	O
</s>
<s>
Sectors	O
are	O
grouped	O
into	O
blocks	O
called	O
granules	O
which	O
vary	O
in	O
size	O
according	O
to	O
total	O
track	O
capacity	O
of	O
the	O
disk	O
media	O
,	O
though	O
granule	O
size	O
for	O
each	O
disk	O
format	B-Application
is	O
constant	O
.	O
</s>
<s>
For	O
forty-cylinder	O
disks	O
formatted	O
in	O
double	O
density	O
,	O
standard	O
for	O
the	O
drives	O
installed	O
in	O
the	O
TRS-80	B-Device
Models	O
III	O
and	O
4	O
,	O
the	O
granule	O
size	O
is	O
six	O
256-byte	O
sectors	O
,	O
or	O
1.5	O
KB	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
assigns	O
numbers	O
to	O
every	O
sector	O
,	O
every	O
track	O
,	O
and	O
every	O
surface	O
.	O
</s>
<s>
For	O
a	O
double-sided	O
floppy	B-Device
disk	I-Device
as	O
formatted	O
on	O
a	O
Model	O
4D	O
,	O
track	O
zero	O
of	O
surface	O
zero	O
and	O
track	O
zero	O
of	O
surface	O
one	O
are	O
grouped	O
together	O
into	O
cylinder	O
zero	O
.	O
</s>
<s>
The	O
disk	O
's	O
directory	O
cylinder	O
is	O
placed	O
during	O
the	O
format	B-Application
process	O
on	O
the	O
middle-numbered	O
cylinder	O
;	O
thus	O
a	O
standard	O
40	O
cylinder	O
disk	O
has	O
its	O
directory	O
installed	O
on	O
cylinder	O
20	O
.	O
</s>
<s>
Thus	O
the	O
theoretical	O
maximum	O
of	O
256	O
files	O
possible	O
on	O
a	O
floppy	B-Device
diskette	I-Device
is	O
realizable	O
only	O
if	O
there	O
is	O
no	O
file	O
fragmentation	O
.	O
</s>
<s>
When	O
TRSDOS	B-Operating_System
formats	O
a	O
disk	O
,	O
all	O
of	O
the	O
parameters	O
associated	O
with	O
the	O
diskette	B-Device
are	O
predetermined	O
.	O
</s>
<s>
The	O
SVC	O
disk	O
primitives	O
are	O
funneled	O
through	O
common	O
system	O
routines	O
contained	O
in	O
the	O
driver	O
software	O
installed	O
for	O
each	O
type	B-Device
of	O
disk	O
storage	O
device	O
.	O
</s>
<s>
The	O
driver	O
for	O
Model	O
III	O
or	O
Model	B-Device
4	I-Device
floppy	B-Device
drives	I-Device
is	O
named	O
and	O
is	O
located	O
in	O
the	O
TRSDOS	B-Operating_System
low	O
memory	O
region	O
.	O
</s>
<s>
Hard	O
disk	O
drives	O
are	O
supplied	O
with	O
their	O
own	O
driver	O
software	O
,	O
and	O
are	O
usually	O
installed	O
in	O
high	O
memory	O
(	O
main	O
64K	O
Z80	B-General_Concept
RAM	O
)	O
above	O
the	O
system	O
pointer	O
,	O
since	O
room	O
in	O
the	O
low	O
memory	O
region	O
is	O
usually	O
insufficient	O
(	O
especially	O
on	O
the	O
Model	B-Device
4	I-Device
since	O
software	O
needed	O
to	O
access	O
its	O
external	O
memory	O
banks	O
cannot	O
reside	O
in	O
high	O
Z80	B-General_Concept
RAM	O
memory	O
because	O
that	O
region	O
exists	O
in	O
the	O
banked	O
RAM	O
swap	O
area	O
)	O
.	O
</s>
<s>
These	O
driver	O
routines	O
establish	O
a	O
linkage	O
protocol	O
between	O
the	O
application	O
requesting	O
disk	O
access	O
and	O
the	O
computer	O
's	O
Floppy	B-Device
Disk	I-Device
Controller	O
hardware	O
.	O
</s>
<s>
TRS-80s	B-Device
use	O
controller	O
chips	O
from	O
the	O
Western	O
Digital	O
series	O
:	O
the	O
WD1791	O
in	O
the	O
Model	B-Device
4	I-Device
non-gate	O
array	O
version	O
,	O
and	O
the	O
WD1773	O
in	O
the	O
Model	B-Device
4	I-Device
Gate	O
Array	O
version	O
.	O
</s>
<s>
When	O
an	O
I/O	B-General_Concept
request	O
is	O
invoked	O
by	O
a	O
higher	O
level	O
SVC	O
,	O
such	O
as	O
a	O
request	O
to	O
READ	O
a	O
file	O
record	O
,	O
the	O
request	O
is	O
translated	O
to	O
that	O
disk	O
primitive	O
(	O
FDC	O
command	O
or	O
status	O
report	O
)	O
needed	O
to	O
satisfy	O
the	O
function	O
request	O
.	O
</s>
<s>
Disk	O
files	O
are	O
supported	O
with	O
two	O
types	O
of	O
access	O
:	O
Record	O
I/O	B-General_Concept
and	O
character	O
I/O	B-General_Concept
.	O
</s>
<s>
Record	O
I/O	B-General_Concept
can	O
be	O
random	O
access	O
(	O
by	O
position	O
SVC	O
requests	O
prior	O
to	O
READ/WRITE	O
)	O
or	O
sequential	O
access	O
using	O
repetitive	O
READs	O
or	O
WRITEs	O
.	O
</s>
<s>
Character	O
(	O
or	O
byte	O
)	O
I/O	B-General_Concept
is	O
accomplished	O
by	O
@GET	O
and	O
@PUT	O
SVC	O
requests	O
and	O
is	O
essentially	O
the	O
same	O
as	O
record	O
I/O	B-General_Concept
with	O
a	O
Logical	O
Record	O
Length	O
(	O
LRL	O
)	O
equal	O
to	O
one	O
.	O
</s>
<s>
This	O
is	O
fixed	O
by	O
the	O
TRS-80	B-Device
disk	O
controller	O
hardware	O
)	O
.	O
</s>
<s>
However	O
,	O
if	O
GET	O
or	O
PUT	O
are	O
used	O
to	O
implement	O
sequential	O
access	O
,	O
then	O
a	O
file	O
can	O
be	O
considered	O
a	O
character	O
I/O	B-General_Concept
device	I-General_Concept
just	O
like	O
a	O
printer	O
,	O
a	O
serial	O
port	O
,	O
or	O
a	O
video	O
display	O
device	O
.	O
</s>
<s>
A	O
byte	O
I/O	B-General_Concept
request	O
is	O
therefore	O
independent	O
of	O
the	O
physical	O
device	O
"	O
connected	O
"	O
to	O
the	O
control	O
block	O
which	O
is	O
requesting	O
the	O
I/O	B-General_Concept
.	O
</s>
<s>
File	O
passwords	O
are	O
up	O
to	O
eight	O
characters	O
obeying	O
the	O
same	O
rules	O
(	O
TRSDOS	B-Operating_System
6	O
versions	O
up	O
to	O
6.2	O
support	O
both	O
owner	O
and	O
user	O
passwords	O
)	O
.	O
</s>
<s>
Entire	O
diskettes	B-Device
can	O
also	O
be	O
assigned	O
master	O
passwords	O
,	O
which	O
may	O
limit	O
user	O
access	O
via	O
the	O
BACKUP	O
and	O
PURGE	O
commands	O
.	O
</s>
<s>
Under	O
TRSDOS	B-Operating_System
and	O
LDOS	B-Operating_System
the	O
system	O
is	O
never	O
"	O
logged	O
in	O
"	O
to	O
any	O
current	O
drive	O
as	O
with	O
CP/M	B-Application
,	O
PC	B-Operating_System
DOS	I-Operating_System
and	O
MS-DOS	B-Application
.	O
</s>
<s>
File	O
access	O
requests	O
issued	O
by	O
applications	O
programs	O
running	O
under	O
TRSDOS	B-Operating_System
work	O
the	O
same	O
way	O
.	O
</s>
<s>
Under	O
TRSDOS/LS	O
-DOS	O
6.x	O
,	O
the	O
standard	O
system	O
command	O
interpreter	O
(	O
SYS1/SYS	O
)	O
can	O
be	O
functionally	O
replaced	O
with	O
a	O
custom	O
interpreter	O
by	O
copying	O
the	O
new	O
interpreter	O
to	O
the	O
system	O
file	O
SYS13/SYS	O
(	O
which	O
in	O
an	O
unmodified	O
installation	O
is	O
a	O
dummy	O
file	O
)	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.x	O
support	O
wildcard	O
characters	O
in	O
filenames	O
,	O
both	O
the	O
single	O
character	O
?	O
</s>
<s>
TRSDOS	B-Operating_System
(	O
version	O
II	O
)	O
was	O
notable	O
for	O
the	O
inclusion	O
of	O
noise	O
words	O
,	O
similar	O
to	O
the	O
1959	O
COBOL	B-Application
specification	O
.	O
</s>
<s>
Since	O
TRSDOS	B-Operating_System
does	O
not	O
have	O
the	O
notion	O
of	O
redirection	O
for	O
disk	O
files	O
as	O
UNIX/Linux	O
and	O
MS-DOS	B-Application
do	O
,	O
the	O
APPEND	O
command	O
is	O
somewhat	O
different	O
in	O
concept	O
than	O
the	O
UNIX	B-Application
or	O
MS-DOS	B-Application
notion	O
of	O
appending	O
via	O
output	O
redirection	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.x	O
do	O
provide	O
I/O	B-General_Concept
redirection	O
for	O
system	O
devices	O
(	O
keyboard	O
*	O
KI	O
,	O
display	O
screen	O
*	O
DO	O
,	O
printer	O
*	O
PR	O
,	O
serial	O
port	O
*	O
CL	O
)	O
,	O
as	O
well	O
as	O
for	O
between	O
devices	O
and	O
disk	O
files	O
.	O
</s>
<s>
The	O
DEVICE	O
command	O
displays	O
a	O
map	O
of	O
I/O	B-General_Concept
links	O
and	O
routes	O
.	O
</s>
<s>
Under	O
DOS	B-Device
and	O
UNIX	B-Application
printing	O
a	O
file	O
can	O
be	O
done	O
with	O
redirection	O
;	O
under	O
UNIX	B-Application
it	O
is	O
normally	O
done	O
by	O
spooling	O
the	O
file	O
to	O
the	O
"	O
line	O
printer	O
"	O
(	O
using	O
the	O
lpr	B-Protocol
command	O
)	O
because	O
UNIX	B-Application
is	O
conventionally	O
a	O
multi-user	O
system	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.x	O
print	O
jobs	O
can	O
be	O
redirected	O
(	O
such	O
as	O
to	O
a	O
disk	O
file	O
)	O
by	O
applying	O
the	O
LINK	O
or	O
ROUTE	O
commands	O
to	O
the	O
system	O
*	O
PR	O
device	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.x	O
do	O
not	O
support	O
subdirectories	O
or	O
user	O
areas	O
.	O
</s>
<s>
However	O
,	O
the	O
DIR	B-Application
and	O
CAT	B-Device
(	O
Catalog	O
)	O
commands	O
for	O
displaying	O
file	O
data	O
support	O
the	O
usual	O
partial	O
filenames	O
,	O
suffixes	O
,	O
and	O
file	O
dates	O
.	O
</s>
<s>
Under	O
TRSDOS/LS	O
-DOS	O
6.x	O
files	O
can	O
be	O
made	O
invisible	O
to	O
the	O
DIR	B-Application
and	O
CAT	B-Device
commands	I-Device
,	O
and	O
can	O
be	O
displayed	O
with	O
the	O
INV	O
parameter	O
(	O
unless	O
any	O
files	O
are	O
password	O
protected	O
and	O
the	O
correct	O
p/w	O
is	O
not	O
given	O
)	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.3	O
can	O
dump	O
the	O
video	O
screen	O
to	O
the	O
line	O
printer	O
by	O
pressing	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
6.x	O
supports	O
both	O
Owner	O
and	O
User	O
passwords	O
(	O
8	O
characters	O
max	O
)	O
for	O
disk	O
files	O
.	O
</s>
<s>
LS-DOS	O
6.3	O
uses	O
the	O
space	O
for	O
the	O
User	O
password	O
for	O
its	O
extended	O
dating	O
scheme	O
(	O
past	O
December	O
31	O
,	O
1987	O
)	O
.	O
</s>
<s>
Both	O
Model	B-Device
4	I-Device
OSes	O
can	O
set	O
various	O
file	O
access	O
levels	O
and	O
permit	O
software	O
write	O
protection	O
for	O
disk	O
files	O
and	O
entire	O
disks	O
.	O
</s>
<s>
Although	O
MS-DOS	B-Application
owes	O
its	O
heritage	O
most	O
closely	O
to	O
CP/M	B-Application
and	O
thence	O
to	O
TOPS-10	B-Operating_System
,	O
many	O
of	O
the	O
file	O
manipulation	O
commands	O
are	O
similar	O
to	O
those	O
of	O
TRSDOS	B-Operating_System
.	O
</s>
<s>
Some	O
of	O
the	O
following	O
TRSDOS	B-Operating_System
commands	O
exist	O
on	O
disk	O
as	O
distinct	O
program	O
files	O
(	O
DIR/CMD	O
,	O
FORMAT/CMD	O
,	O
BACKUP/CMD	O
)	O
while	O
all	O
others	O
exist	O
as	O
modules	O
condensed	O
into	O
the	O
library	O
files	O
(	O
technically	O
Partitioned	O
Data	O
Sets	O
or	O
PDSs	O
)	O
SYS6/SYS	O
,	O
SYS7/SYS	O
and	O
SYS8/SYS	O
;	O
these	O
include	O
the	O
TRSDOS	B-Operating_System
commands	O
CAT	B-Device
,	O
COPY	B-Device
,	O
LIST	O
,	O
REMOVE	O
,	O
RENAME	B-Device
etc	O
.	O
</s>
<s>
Some	O
typical	O
TRSDOS	B-Operating_System
utilities	O
:	O
</s>
<s>
+	O
TRSDOS	B-Operating_System
commands	O
and	O
counterparts	O
in	O
other	O
operating	B-General_Concept
systems	I-General_Concept
Command	O
DOS	B-Device
,	O
OS/2	B-Application
,	O
Windows	B-Application
Unix	B-Application
,	O
Unix-like	B-Operating_System
Description	O
APPEND	O
type	B-Device
file1	O
>>	O
file2	O
cat	B-Device
file	O
>>	O
file2	O
Under	O
TRSDOS	B-Operating_System
6.x	O
,	O
the	O
source	O
of	O
the	O
appended	O
data	O
may	O
be	O
a	O
system	O
input	O
device	O
such	O
as	O
*	O
KI	O
.	O
</s>
<s>
ATTRIB	O
attrib	O
chmod	B-Application
ATTRIB	O
,	O
PROT	O
,	O
and	O
the	O
chmod	B-Application
UNIX	B-Application
command	O
are	O
all	O
somewhat	O
different	O
in	O
their	O
semantics	O
.	O
</s>
<s>
UNIX/Linux	O
is	O
multi-user	O
and	O
each	O
user	O
can	O
control	O
read	O
,	O
write	O
,	O
and	O
execute	O
permissions	O
on	O
his	O
or	O
her	O
own	O
files	O
and	O
directories	O
.	O
</s>
<s>
MS-DOS	B-Application
is	O
single	O
user	O
and	O
the	O
file	O
attributes	O
for	O
"	O
read-only	O
,	O
"	O
"	O
hidden	O
,	O
"	O
and	O
"	O
system	O
"	O
are	O
advisory	O
in	O
nature	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
was	O
single	O
user	O
.	O
</s>
<s>
TRSDOS	B-Operating_System
6.x	O
ATTRIB	O
can	O
modify	O
protection	O
status	O
of	O
all	O
files	O
on	O
a	O
disk	O
volume	O
if	O
the	O
disk	O
's	O
master	O
password	O
is	O
given	O
.	O
</s>
<s>
AUTO	O
AUTOEXEC.BAT	O
~	O
/.profile	O
or	O
~	O
/.login	O
or	O
/etc/rc	O
*	O
The	O
AUTO	O
command	O
sets	O
an	O
automatic	O
command	O
to	O
be	O
executed	O
on	O
TRSDOS	B-Operating_System
boot	O
;	O
under	O
MS-DOS	B-Application
the	O
special	O
,	O
reserved	O
file	O
named	O
AUTOEXEC.BAT	O
contained	O
a	O
list	O
of	O
such	O
commands	O
.	O
</s>
<s>
TRSDOS/LS	O
-DOS	O
6.x	O
support	O
Job	O
Control	O
Language	O
in	O
which	O
any	O
text	O
file	O
with	O
the	O
suffix	O
/JCL	O
could	O
batch	O
process	O
(	O
using	O
the	O
DO	O
command	O
)	O
any	O
number	O
of	O
executable	O
program	O
files	O
.	O
</s>
<s>
On	O
UNIX	B-Application
a	O
set	O
of	O
one	O
or	O
more	O
rc	O
files	O
under	O
/etc/	O
are	O
a	O
set	O
of	O
boot	O
time	O
"	O
run	O
commands	O
"	O
and	O
special	O
"	O
dot	O
files	O
"	O
in	O
a	O
user	O
's	O
home	O
directory	O
are	O
run	O
for	O
each	O
time	O
that	O
a	O
given	O
user	O
logs	O
into	O
the	O
system	O
.	O
</s>
<s>
UNIX	B-Application
supports	O
many	O
other	O
"	O
dotfiles	O
"	O
for	O
many	O
of	O
its	O
commands	O
which	O
are	O
akin	O
to	O
the	O
Macintosh	B-Device
"	O
preferences	O
"	O
folder	O
contents	O
.	O
</s>
<s>
BACKUP	O
diskcopy	B-Device
,	O
tar	B-Application
tar	B-Application
,	O
cpio	B-Application
,	O
pax	B-Device
,	O
(	O
many	O
others	O
)	O
TRSDOS/LS	O
-DOS	O
6.x	O
include	O
the	O
BACKUP/CMD	O
utility	O
which	O
can	O
mass	O
copy	B-Device
files	O
specified	O
by	O
partial	O
filename	O
matches	O
,	O
file	O
suffixes	O
(	O
e.g.	O
</s>
<s>
BACKUP	O
can	O
be	O
made	O
to	O
first	O
query	O
for	O
permission	O
to	O
copy	B-Device
each	O
file	O
with	O
the	O
(	O
Q	O
=	O
Y	O
)	O
)	O
parameter	O
.	O
</s>
<s>
CAT	B-Device
The	O
TRSDOS	B-Operating_System
CATalog	O
command	O
displays	O
one	O
line	O
giving	O
information	O
on	O
the	O
selected	O
drive	O
(	O
disk	O
name	O
,	O
capacity	O
,	O
date	O
)	O
and	O
a	O
listing	O
of	O
the	O
filenames	O
with	O
their	O
extensions	O
present	O
on	O
the	O
disk	O
.	O
</s>
<s>
CAT	B-Device
uses	O
the	O
same	O
parameters	O
as	O
DIR	B-Application
for	O
viewing	O
INVisible	O
and	O
SYStem	O
files	O
.	O
</s>
<s>
CLOCK	O
prompt	O
$t	O
*	O
in	O
some	O
shells	O
:	O
PS1	O
=	O
"	O
...	O
t	O
...	O
*	O
CLOCK	O
installs	O
an	O
interrupt	O
task	O
that	O
shows	O
the	O
system	O
time	O
in	O
the	O
upper	O
corner	O
of	O
the	O
display	O
;	O
no	O
exactly	O
corresponding	O
feature	O
exists	O
in	O
MS-DOS	B-Application
or	O
UNIX	B-Application
,	O
though	O
many	O
programs	O
provided	O
similar	O
features	O
for	O
DOS	B-Device
and	O
the	O
common	O
UNIX	B-Application
shells	O
could	O
embed	O
the	O
time	O
into	O
their	O
user-defined	O
"	O
prompt	O
string	O
"	O
.	O
</s>
<s>
CLS	O
cls	O
clear	B-Device
Clear	B-Device
video	O
display	O
and	O
home	O
cursor	O
COMM	O
Under	O
TRSDOS	B-Operating_System
6.x	O
,	O
COMM/CMD	O
is	O
a	O
terminal	O
program	O
that	O
establishes	O
communications	O
between	O
the	O
Model	B-Device
4	I-Device
's	O
RS-232C	O
serial	O
port	O
and	O
that	O
of	O
another	O
computer	O
,	O
a	O
modem	O
or	O
serial	O
printer/plotter	O
.	O
</s>
<s>
COPY	B-Device
copy	B-Device
cp	B-Application
Under	O
TRSDOS	B-Operating_System
6.x	O
,	O
the	O
COPY	B-Device
command	O
can	O
be	O
used	O
to	O
transfer	O
information	O
between	O
system	O
devices	O
as	O
well	O
as	O
disk	O
files	O
.	O
</s>
<s>
For	O
example	O
,	O
COPY	B-Device
*	O
KI	O
*	O
PR	O
will	O
turn	O
the	O
computer	O
(	O
if	O
connected	O
to	O
an	O
active	O
line	O
printer	O
)	O
into	O
a	O
typewriter	O
,	O
as	O
each	O
character	O
typed	O
at	O
the	O
keyboard	O
is	O
sent	O
to	O
the	O
*	O
PR	O
device	O
as	O
well	O
as	O
the	O
*	O
DO	O
device	O
.	O
</s>
<s>
This	O
is	O
effectively	O
the	O
same	O
as	O
the	O
TRSDOS	B-Operating_System
command	O
LINK	O
*	O
KI	O
*	O
PR	O
.	O
</s>
<s>
DEBUG	B-Device
debug	B-Device
Optional	O
filespec	O
also	O
performs	O
LOAD	O
function	O
on	O
a	O
target	O
/CMD	O
machine	O
code	O
program	O
;	O
(	O
ext	O
)	O
loads	O
additional	O
debugger	O
commands	O
from	O
system	O
file	O
SYS9/SYS	O
DEVICE	O
Displays	O
the	O
status	O
of	O
the	O
system	O
drives	O
and	O
system	O
logical	O
devices	O
,	O
as	O
well	O
as	O
the	O
existing	O
ROUTEs	O
and	O
LINKs	O
between	O
them	O
.	O
</s>
<s>
DIR	B-Application
dir	B-Application
ls	B-Application
DIR	B-Application
displays	O
the	O
same	O
files	O
that	O
would	O
be	O
selected	O
by	O
the	O
BACKUP	O
command	O
,	O
and	O
so	O
is	O
useful	O
as	O
a	O
preview	O
tool	O
.	O
</s>
<s>
DISKCOPY	B-Device
diskcopy	B-Device
LS-DOS	O
6.3	O
includes	O
the	O
DISKCOPY/CMD	O
utility	O
which	O
makes	O
an	O
exact	O
copy	B-Device
of	O
a	O
source	O
disk	O
by	O
formatting	O
and	O
copying	O
to	O
a	O
blank	O
destination	O
disk	O
.	O
</s>
<s>
Three	O
included	O
with	O
TRSDOS	B-Operating_System
6.x	O
are	O
FORMS/FLT	O
which	O
is	O
used	O
for	O
formatted	O
printing	O
,	O
KSM/FLT	O
which	O
is	O
a	O
keyboard	O
macro	O
facility	O
,	O
and	O
CLICK/FLT	O
which	O
causes	O
the	O
Model	B-Device
4	I-Device
speaker	O
to	O
beep	O
every	O
time	O
a	O
key	O
is	O
pressed	O
.	O
</s>
<s>
FORMAT	B-Application
format	B-Application
mkfs	B-Device
Defaults	O
to	O
40	O
track	O
,	O
single-sided	O
on	O
Models	O
III	O
and	O
4	O
,	O
double-sided	O
on	O
Model	O
4D	O
.	O
</s>
<s>
All	O
Model	O
4Ds	O
and	O
most	O
Model	O
4s	O
can	O
format	B-Application
42	O
tracks	O
although	O
drives	O
supplied	O
by	O
Radio	O
Shack	O
are	O
nominally	O
40	O
track	O
.	O
</s>
<s>
FORMSUnder	O
TRSDOS	B-Operating_System
6.x	O
,	O
sets	O
parameters	O
for	O
data	O
sent	O
to	O
the	O
system	O
*	O
PR	O
device	O
after	O
the	O
FORMS	O
filter	O
has	O
been	O
attached	O
to	O
the	O
*	O
PR	O
device	O
.	O
</s>
<s>
FREE	O
chkdsk	B-Device
df	B-Device
TRSDOS	B-Operating_System
6.x	O
displays	O
ASCII	O
map	O
showing	O
disk	O
granules	O
occupied	O
by	O
active	O
files	O
with	O
xxxxxx	O
;	O
the	O
directory	O
cylinder	O
is	O
shown	O
as	O
DDDDDD	O
.	O
</s>
<s>
GETDISK/GETTAPE	O
dd	B-Application
KILL	O
del	B-Device
rm	B-Application
Starting	O
with	O
TRSDOS	B-Operating_System
6.0	O
KILL	O
was	O
replaced	O
by	O
REMOVE	O
(	O
per	O
LSI	O
Journal	O
article	O
"	O
Thou	O
Shalt	O
Not	O
Kill	O
"	O
)	O
LIST	O
type	B-Device
cat	B-Device
Under	O
TRSDOS/LS	O
-DOS	O
6.x	O
,	O
the	O
LIST	O
command	O
can	O
display	O
or	O
print	O
the	O
contents	O
of	O
non-ASCII	O
files	O
with	O
the	O
HEX	O
parameter	O
.	O
</s>
<s>
LOAD	O
filespec	O
Program	O
invocation	O
under	O
TRSDOS	B-Operating_System
,	O
DOS	B-Device
and	O
UNIX	B-Application
is	O
done	O
by	O
filename	O
;	O
no	O
explicit	O
LOAD	O
command	O
is	O
required	O
for	O
normal	O
binary	O
executables	O
nor	O
for	O
text	O
command	O
files	O
(	O
batch	O
files	O
in	O
DOS	B-Device
and	O
shell	B-Language
scripts	I-Language
in	O
UNIX/Linux	O
)	O
.	O
</s>
<s>
The	O
LOAD	O
command	O
under	O
TRSDOS	B-Operating_System
would	O
load	O
a	O
binary	O
program	O
into	O
memory	O
,	O
but	O
would	O
not	O
execute	O
it	O
;	O
neither	O
DOS	B-Device
nor	O
UNIX	B-Application
has	O
an	O
equivalent	O
.	O
</s>
<s>
LOAD	O
under	O
TRSDOS	B-Operating_System
is	O
almost	O
always	O
used	O
to	O
make	O
a	O
machine	O
code	O
Z80	B-General_Concept
program	O
(	O
/CMD	O
file	O
)	O
available	O
to	O
the	O
system	O
debugger	O
for	O
examination	O
or	O
modification	O
.	O
</s>
<s>
For	O
example	O
,	O
flag	O
A	O
is	O
the	O
DOS	B-Device
Allocation	O
byte	O
,	O
which	O
the	O
BACKUP	O
command	O
uses	O
to	O
specify	O
the	O
beginning	O
cylinder	O
of	O
a	O
disk	O
to	O
start	O
copying	O
files	O
.	O
</s>
<s>
PATCH	B-Application
patch	B-Application
All	O
versions	O
of	O
TRSDOS	B-Operating_System
include	O
the	O
PATCH/CMD	O
utility	O
.	O
</s>
<s>
This	O
permits	O
modification	O
of	O
machine	O
code	O
/CMD	O
files	O
using	O
patch	B-Application
data	O
supplied	O
by	O
a	O
/FIX	O
file	O
in	O
hexadecimal	O
ASCII	O
format	B-Application
.	O
</s>
<s>
PRINT	O
type	B-Device
file	O
>>	O
prn	B-Application
lpr	B-Protocol
Under	O
TRSDOS	B-Operating_System
6.x	O
an	O
interrupt	O
task	O
is	O
provided	O
to	O
dump	O
the	O
current	O
video	O
display	O
to	O
a	O
line	O
printer	O
at	O
any	O
time	O
.	O
</s>
<s>
PURGE	O
TRSDOS/LS	O
-DOS	O
6.x	O
support	O
the	O
PURGE	O
command	O
which	O
will	O
mass	O
delete	B-Device
files	O
specified	O
by	O
partial	O
filename	O
,	O
file	O
suffixes	O
,	O
or	O
file	O
dates	O
.	O
</s>
<s>
PURGE	O
will	O
query	O
the	O
user	O
for	O
permission	O
to	O
delete	B-Device
each	O
file	O
unless	O
the	O
(	O
Q	O
=	O
N	O
)	O
parameter	O
is	O
given	O
.	O
</s>
<s>
RENAME	B-Device
ren	B-Device
or	O
rename	B-Device
mv	O
Under	O
TRSDOS	B-Operating_System
6.x	O
the	O
user	O
may	O
rename	B-Device
individual	O
files	O
or	O
the	O
entire	O
diskette	B-Device
.	O
</s>
<s>
TAPE100	O
TAPE100/CMD	O
reads	O
and	O
writes	O
cassette	O
tapes	O
recorded	O
by	O
the	O
TRS-80	B-Operating_System
Model	I-Operating_System
100	I-Operating_System
laptop	O
as	O
TRSDOS	B-Operating_System
6.x	O
disk	O
files	O
.	O
</s>
<s>
This	O
requires	O
use	O
of	O
the	O
Model	B-Device
4	I-Device
cassette	O
interface	O
,	O
which	O
the	O
Model	O
4P	O
transportable	O
lacks	O
.	O
</s>
