<s>
CP/M	B-Application
,	O
originally	O
standing	O
for	O
Control	B-Application
Program/Monitor	I-Application
and	O
later	O
Control	B-Application
Program	I-Application
for	I-Application
Microcomputers	I-Application
,	O
is	O
a	O
mass-market	O
operating	B-General_Concept
system	I-General_Concept
created	O
in	O
1974	O
for	O
Intel	O
8080/85	O
-based	O
microcomputers	B-Architecture
by	O
Gary	O
Kildall	O
of	O
Digital	O
Research	O
,	O
Inc	O
.	O
</s>
<s>
Initially	O
confined	O
to	O
single-tasking	O
on	O
8-bit	O
processors	O
and	O
no	O
more	O
than	O
64	O
kilobytes	O
of	O
memory	O
,	O
later	O
versions	O
of	O
CP/M	B-Application
added	O
multi-user	O
variations	O
and	O
were	O
migrated	O
to	O
16-bit	B-Device
processors	I-Device
.	O
</s>
<s>
The	O
combination	O
of	O
CP/M	B-Application
and	O
S-100	B-Architecture
bus	I-Architecture
computers	O
became	O
an	O
early	O
standard	O
in	O
the	O
microcomputer	B-Architecture
industry	O
.	O
</s>
<s>
This	O
computer	B-Device
platform	I-Device
was	O
widely	O
used	O
in	O
business	O
through	O
the	O
late	O
1970s	O
and	O
into	O
the	O
mid-1980s	O
.	O
</s>
<s>
CP/M	B-Application
increased	O
the	O
market	O
size	O
for	O
both	O
hardware	O
and	O
software	O
by	O
greatly	O
reducing	O
the	O
amount	O
of	O
programming	O
required	O
to	O
install	O
an	O
application	O
on	O
a	O
new	O
manufacturer	O
's	O
computer	O
.	O
</s>
<s>
An	O
important	O
driver	O
of	O
software	O
innovation	O
was	O
the	O
advent	B-Application
of	O
(	O
comparatively	O
)	O
low-cost	O
microcomputers	B-Architecture
running	O
CP/M	B-Application
,	O
as	O
independent	O
programmers	O
and	O
hackers	O
bought	O
them	O
and	O
shared	O
their	O
creations	O
in	O
user	O
groups	O
.	O
</s>
<s>
CP/M	B-Application
was	O
eventually	O
displaced	O
by	O
DOS	B-Device
following	O
the	O
1981	O
introduction	O
of	O
the	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
Gary	O
Kildall	O
originally	O
developed	O
CP/M	B-Application
during	O
1974	O
,	O
as	O
an	O
operating	B-General_Concept
system	I-General_Concept
to	O
run	O
on	O
an	O
Intel	O
Intellec-8	O
development	O
system	O
,	O
equipped	O
with	O
a	O
Shugart	O
Associates	O
8-inch	O
floppy-disk	O
drive	O
interfaced	O
via	O
a	O
custom	O
floppy-disk	B-Device
controller	I-Device
.	O
</s>
<s>
It	O
was	O
written	O
in	O
Kildall	O
's	O
own	O
PL/M	B-Language
(	O
Programming	O
Language	O
for	O
Microcomputers	B-Architecture
)	O
.	O
</s>
<s>
Various	O
aspects	O
of	O
CP/M	B-Application
were	O
influenced	O
by	O
the	O
TOPS-10	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
of	O
the	O
DECsystem-10	B-Device
mainframe	B-Architecture
computer	I-Architecture
,	O
which	O
Kildall	O
had	O
used	O
as	O
a	O
development	O
environment	O
.	O
</s>
<s>
An	O
early	O
outside	O
licensee	O
of	O
CP/M	B-Application
was	O
Gnat	O
Computers	O
,	O
an	O
early	O
microcomputer	B-Architecture
developer	O
out	O
of	O
San	O
Diego	O
,	O
California	O
.	O
</s>
<s>
In	O
1977	O
,	O
the	O
company	O
was	O
granted	O
the	O
license	O
to	O
use	O
CP/M	B-Application
1.0	O
for	O
any	O
micro	O
they	O
desired	O
for	O
$90	O
.	O
</s>
<s>
Within	O
the	O
year	O
,	O
demand	O
for	O
CP/M	B-Application
was	O
so	O
high	O
that	O
Digital	O
Research	O
was	O
able	O
to	O
increase	O
the	O
license	O
to	O
tens	O
of	O
thousands	O
of	O
dollars	O
.	O
</s>
<s>
Under	O
Kildall	O
's	O
direction	O
,	O
the	O
development	O
of	O
CP/M	B-Application
2.0	O
was	O
mostly	O
carried	O
out	O
by	O
John	O
Pierce	O
in	O
1978	O
.	O
</s>
<s>
She	O
started	O
by	O
debugging	O
CP/M	B-Application
2.0	O
,	O
and	O
later	O
became	O
influential	O
as	O
key	O
developer	O
for	O
CP/M	B-Application
2.2	O
and	O
CP/M	B-Application
Plus	O
.	O
</s>
<s>
Other	O
early	O
developers	O
of	O
the	O
CP/M	B-Application
base	O
included	O
Robert	O
"	O
Bob	O
"	O
Silberstein	O
and	O
David	O
"	O
Dave	O
"	O
K	O
.	O
Brown	O
.	O
</s>
<s>
CP/M	B-Application
originally	O
stood	O
for	O
"	O
Control	B-Application
Program/Monitor	I-Application
"	O
,	O
a	O
name	O
which	O
implies	O
a	O
resident	B-Application
monitor	I-Application
—	O
a	O
primitive	O
precursor	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
However	O
,	O
during	O
the	O
conversion	O
of	O
CP/M	B-Application
to	O
a	O
commercial	O
product	O
,	O
trademark	O
registration	O
documents	O
filed	O
in	O
November	O
1977	O
gave	O
the	O
product	O
's	O
name	O
as	O
"	O
Control	B-Application
Program	I-Application
for	I-Application
Microcomputers	I-Application
"	O
.	O
</s>
<s>
The	O
CP/M	B-Application
name	O
follows	O
a	O
prevailing	O
naming	O
scheme	O
of	O
the	O
time	O
,	O
as	O
in	O
Kildall	O
's	O
PL/M	B-Language
language	O
,	O
and	O
Prime	O
Computer	O
's	O
PL/P	B-Language
(	O
Programming	O
Language	O
for	O
Prime	O
)	O
,	O
both	O
suggesting	O
IBM	O
's	O
PL/I	B-Language
;	O
and	O
IBM	O
's	O
CP/CMS	B-Application
operating	B-General_Concept
system	I-General_Concept
,	O
which	O
Kildall	O
had	O
used	O
when	O
working	O
at	O
the	O
NPS	O
.	O
</s>
<s>
This	O
renaming	O
of	O
CP/M	B-Application
was	O
part	O
of	O
a	O
larger	O
effort	O
by	O
Kildall	O
and	O
his	O
wife	O
with	O
business	O
partner	O
,	O
Dorothy	O
McEwen	O
to	O
convert	O
Kildall	O
's	O
personal	O
project	O
of	O
CP/M	B-Application
and	O
the	O
Intel-contracted	O
PL/M	B-Language
compiler	O
into	O
a	O
commercial	O
enterprise	O
.	O
</s>
<s>
The	O
Kildalls	O
intended	O
to	O
establish	O
the	O
Digital	O
Research	O
brand	O
and	O
its	O
product	O
lines	O
as	O
synonymous	O
with	O
"	O
microcomputer	B-Architecture
"	O
in	O
the	O
consumer	O
's	O
mind	O
,	O
similar	O
to	O
what	O
IBM	O
and	O
Microsoft	O
together	O
later	O
successfully	O
accomplished	O
in	O
making	O
"	O
personal	O
computer	O
"	O
synonymous	O
with	O
their	O
product	O
offerings	O
.	O
</s>
<s>
By	O
September	O
1981	O
,	O
Digital	O
Research	O
had	O
sold	O
more	O
than	O
CP/M	B-Application
licenses	O
;	O
InfoWorld	O
stated	O
that	O
the	O
actual	O
market	O
was	O
likely	O
larger	O
because	O
of	O
sublicenses	O
.	O
</s>
<s>
Many	O
different	O
companies	O
produced	O
CP/M	B-Application
-based	O
computers	O
for	O
many	O
different	O
markets	O
;	O
the	O
magazine	O
stated	O
that	O
"	O
CP/M	B-Application
is	O
well	O
on	O
its	O
way	O
to	O
establishing	O
itself	O
as	O
the	O
small-computer	O
operating	O
system	O
"	O
.	O
</s>
<s>
The	O
companies	O
chose	O
to	O
support	O
CP/M	B-Application
because	O
of	O
its	O
large	O
library	O
of	O
software	O
.	O
</s>
<s>
The	O
Xerox	B-Device
820	I-Device
ran	O
the	O
operating	B-General_Concept
system	I-General_Concept
because	O
"	O
where	O
there	O
are	O
literally	O
thousands	O
of	O
programs	O
written	O
for	O
it	O
,	O
it	O
would	O
be	O
unwise	O
not	O
to	O
take	O
advantage	O
of	O
it	O
"	O
,	O
Xerox	O
said	O
.	O
</s>
<s>
(	O
Xerox	O
included	O
a	O
Howard	O
W	O
.	O
Sams	O
CP/M	B-Application
manual	O
as	O
compensation	O
for	O
Digital	O
Research	O
's	O
documentation	O
,	O
which	O
InfoWorld	O
in	O
1982	O
described	O
as	O
atrocious	O
.	O
)	O
</s>
<s>
By	O
1984	O
,	O
Columbia	O
University	O
used	O
the	O
same	O
source	O
code	O
to	O
build	O
Kermit	B-Protocol
binaries	O
for	O
more	O
than	O
a	O
dozen	O
different	O
CP/M	B-Application
systems	O
,	O
plus	O
a	O
generic	O
version	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
was	O
described	O
as	O
a	O
"	O
software	B-Architecture
bus	I-Architecture
"	O
,	O
allowing	O
multiple	O
programs	O
to	O
interact	O
with	O
different	O
hardware	O
in	O
a	O
standardized	O
way	O
.	O
</s>
<s>
Programs	O
written	O
for	O
CP/M	B-Application
were	O
typically	O
portable	O
among	O
different	O
machines	O
,	O
usually	O
requiring	O
only	O
the	O
specification	O
of	O
the	O
escape	O
sequences	O
for	O
control	O
of	O
the	O
screen	B-General_Concept
and	O
printer	O
.	O
</s>
<s>
This	O
portability	O
made	O
CP/M	B-Application
popular	O
,	O
and	O
much	O
more	O
software	O
was	O
written	O
for	O
CP/M	B-Application
than	O
for	O
operating	B-General_Concept
systems	I-General_Concept
that	O
ran	O
on	O
only	O
one	O
brand	O
of	O
hardware	O
.	O
</s>
<s>
One	O
restriction	O
on	O
portability	O
was	O
that	O
certain	O
programs	O
used	O
the	O
extended	O
instruction	O
set	O
of	O
the	O
Z80	B-General_Concept
processor	O
and	O
would	O
not	O
operate	O
on	O
an	O
8080	B-General_Concept
or	O
8085	B-General_Concept
processor	O
.	O
</s>
<s>
Another	O
was	O
graphics	O
routines	O
,	O
especially	O
in	O
games	O
and	O
graphics	O
programs	O
,	O
which	O
were	O
generally	O
machine-specific	O
as	O
they	O
used	O
direct	O
hardware	O
access	O
for	O
speed	O
,	O
bypassing	O
the	O
OS	O
and	O
BIOS	O
(	O
this	O
was	O
also	O
a	O
common	O
problem	O
in	O
early	O
DOS	B-Device
machines	O
)	O
.	O
</s>
<s>
Bill	O
Gates	O
claimed	O
that	O
the	O
Apple	B-Device
II	I-Device
series	I-Device
with	O
a	O
Z-80	B-Device
SoftCard	I-Device
was	O
the	O
single	O
most-popular	O
CP/M	B-Application
hardware	B-Device
platform	I-Device
.	O
</s>
<s>
Many	O
different	O
brands	O
of	O
machines	O
ran	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
some	O
notable	O
examples	O
being	O
the	O
Altair	B-Architecture
8800	I-Architecture
,	O
the	O
IMSAI	B-Device
8080	I-Device
,	O
the	O
Osborne	B-Device
1	I-Device
and	O
Kaypro	O
luggables	B-Device
,	O
and	O
MSX	B-Operating_System
computers	O
.	O
</s>
<s>
The	O
best-selling	O
CP/M	B-Application
-capable	O
system	O
of	O
all	O
time	O
was	O
probably	O
the	O
Amstrad	B-Device
PCW	I-Device
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
CP/M	B-Application
was	O
also	O
available	O
on	O
Research	O
Machines	O
educational	O
computers	O
(	O
with	O
the	O
CP/M	B-Application
source	O
code	O
published	O
as	O
an	O
educational	O
resource	O
)	O
,	O
and	O
for	O
the	O
BBC	B-Device
Micro	I-Device
when	O
equipped	O
with	O
a	O
Z80	B-General_Concept
co-processor	O
.	O
</s>
<s>
Furthermore	O
,	O
it	O
was	O
available	O
for	O
the	O
Amstrad	B-Device
CPC	I-Device
series	O
,	O
the	O
Commodore	B-Device
128	I-Device
,	O
TRS-80	B-Device
,	O
and	O
later	O
models	O
of	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
.	O
</s>
<s>
CP/M3	O
was	O
also	O
used	O
on	O
the	O
NIAT	O
,	O
a	O
custom	O
handheld	O
computer	O
designed	O
for	O
A	O
.	O
C	B-Language
.	O
Nielsen	O
's	O
internal	O
use	O
with	O
1MB	O
of	O
SSD	B-Device
memory	O
.	O
</s>
<s>
In	O
1979	O
,	O
a	O
multi-user	O
compatible	O
derivative	O
of	O
CP/M	B-Application
was	O
released	O
.	O
</s>
<s>
MP/M	B-Operating_System
allowed	O
multiple	O
users	O
to	O
connect	O
to	O
a	O
single	O
computer	O
,	O
using	O
multiple	O
terminals	B-General_Concept
to	O
provide	O
each	O
user	O
with	O
a	O
screen	B-General_Concept
and	O
keyboard	O
.	O
</s>
<s>
Later	O
versions	O
ran	O
on	O
16-bit	B-Device
processors	I-Device
.	O
</s>
<s>
The	O
last	O
8-bit	O
version	O
of	O
CP/M	B-Application
was	O
version	O
3	O
,	O
often	O
called	O
CP/MPlus	O
,	O
released	O
in	O
1983	O
.	O
</s>
<s>
It	O
incorporated	O
the	O
bank	B-General_Concept
switching	I-General_Concept
memory	O
management	O
of	O
MP/M	B-Operating_System
in	O
a	O
single-user	O
single-task	O
operating	B-General_Concept
system	I-General_Concept
compatible	O
with	O
CP/M2.2	O
applications	O
.	O
</s>
<s>
CP/M3	O
could	O
therefore	O
use	O
more	O
than	O
64KB	O
of	O
memory	O
on	O
an	O
8080	B-General_Concept
or	O
Z80	B-General_Concept
processor	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
distribution	O
software	O
also	O
included	O
a	O
relocating	O
assembler	B-Application
and	O
linker	O
.	O
</s>
<s>
CP/M3	O
was	O
available	O
for	O
the	O
last	O
generation	O
of	O
8-bit	O
computers	O
,	O
notably	O
the	O
Amstrad	B-Device
PCW	I-Device
,	O
the	O
Amstrad	B-Device
CPC	I-Device
,	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
+3	O
,	O
the	O
Commodore	B-Device
128	I-Device
,	O
MSX	B-Operating_System
machines	O
and	O
the	O
Radio	B-Device
Shack	I-Device
TRS-80	I-Device
Model	O
4	O
.	O
</s>
<s>
There	O
were	O
versions	O
of	O
CP/M	B-Application
for	O
some	O
16-bit	B-Device
CPUs	O
as	O
well	O
.	O
</s>
<s>
The	O
first	O
version	O
in	O
the	O
16-bit	B-Device
family	O
was	O
CP/M	B-Operating_System
-86	I-Operating_System
for	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
in	O
November	O
1981	O
.	O
</s>
<s>
Kathryn	O
Strutynski	O
was	O
the	O
project	O
manager	O
for	O
the	O
evolving	O
CP/M	B-Operating_System
-86	I-Operating_System
line	O
of	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
At	O
this	O
point	O
,	O
the	O
original	O
8-bit	O
CP/M	B-Application
became	O
known	O
by	O
the	O
retronym	O
CP/M	B-Application
-80	I-Application
to	O
avoid	O
confusion	O
.	O
</s>
<s>
CP/M	B-Operating_System
-86	I-Operating_System
was	O
expected	O
to	O
be	O
the	O
standard	O
operating	B-General_Concept
system	I-General_Concept
of	O
the	O
new	O
IBM	B-Device
PCs	I-Device
,	O
but	O
DRI	O
and	O
IBM	O
were	O
unable	O
to	O
negotiate	O
development	O
and	O
licensing	O
terms	O
.	O
</s>
<s>
IBM	O
turned	O
to	O
Microsoft	O
instead	O
,	O
and	O
Microsoft	O
delivered	O
PC	O
DOS	B-Device
based	O
on	O
86-DOS	B-Operating_System
.	O
</s>
<s>
Although	O
CP/M	B-Operating_System
-86	I-Operating_System
became	O
an	O
option	O
for	O
the	O
IBM	B-Device
PC	I-Device
after	O
DRI	O
threatened	O
legal	O
action	O
,	O
it	O
never	O
overtook	O
Microsoft	O
's	O
system	O
.	O
</s>
<s>
Most	O
customers	O
were	O
repelled	O
by	O
the	O
significantly	O
greater	O
price	O
IBM	O
charged	O
for	O
CP/M	B-Operating_System
-86	I-Operating_System
over	O
PC	O
DOS	B-Device
(	O
and	O
,	O
respectively	O
)	O
.	O
</s>
<s>
When	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
put	O
out	O
the	O
Rainbow	B-Device
100	I-Device
to	O
compete	O
with	O
IBM	O
,	O
it	O
came	O
with	O
CP/M	B-Application
-80	I-Application
using	O
a	O
Z80	B-General_Concept
chip	O
,	O
CP/M	B-Operating_System
-86	I-Operating_System
or	O
MS-DOS	B-Application
using	O
an	O
8088	O
microprocessor	O
,	O
or	O
CP/M-86/80	B-Operating_System
using	O
both	O
.	O
</s>
<s>
The	O
Z80	B-General_Concept
and	O
8088	O
CPUs	O
ran	O
concurrently	O
.	O
</s>
<s>
A	O
benefit	O
of	O
the	O
Rainbow	O
was	O
that	O
it	O
could	O
continue	O
to	O
run	O
8-bit	O
CP/M	B-Application
software	O
,	O
preserving	O
a	O
user	O
's	O
possibly	O
sizable	O
investment	O
as	O
they	O
moved	O
into	O
the	O
16-bit	B-Device
world	O
of	O
MS-DOS	B-Application
.	O
</s>
<s>
A	O
similar	O
dual-processor	B-Operating_System
adaption	O
for	O
the	O
was	O
named	O
CP/M	B-Operating_System
8-16	I-Operating_System
.	O
</s>
<s>
The	O
CP/M	B-Operating_System
-86	I-Operating_System
adaptation	O
for	O
the	O
8085/8088	O
-based	O
Zenith	B-Device
Z-100	I-Device
also	O
supported	O
running	O
programs	O
for	O
both	O
of	O
its	O
CPUs	O
.	O
</s>
<s>
Soon	O
following	O
CP/M	B-Operating_System
-86	I-Operating_System
,	O
another	O
16-bit	B-Device
version	O
of	O
CP/M	B-Application
was	O
CP/M	B-Application
-68K	O
for	O
the	O
Motorola	B-Device
68000	I-Device
.	O
</s>
<s>
The	O
original	O
version	O
of	O
CP/M	B-Application
-68K	O
in	O
1982	O
was	O
written	O
in	O
Pascal/MT	B-Language
+68k	O
,	O
but	O
it	O
was	O
ported	O
to	O
C	B-Language
later	O
on	O
.	O
</s>
<s>
CP/M	B-Application
-68K	O
,	O
already	O
running	O
on	O
the	O
Motorola	O
EXORmacs	O
systems	O
,	O
was	O
initially	O
to	O
be	O
used	O
in	O
the	O
Atari	B-Device
ST	I-Device
computer	O
,	O
but	O
Atari	O
decided	O
to	O
go	O
with	O
a	O
newer	O
disk	O
operating	B-General_Concept
system	I-General_Concept
called	O
GEMDOS	B-Operating_System
.	O
</s>
<s>
CP/M	B-Application
-68K	O
was	O
also	O
used	O
on	O
the	O
SORD	O
M68	O
and	O
M68MX	O
computers	O
.	O
</s>
<s>
In	O
1982	O
,	O
there	O
was	O
also	O
a	O
port	O
from	O
CP/M	B-Application
-68K	O
to	O
the	O
16-bit	B-Device
Zilog	B-Device
Z8000	I-Device
for	O
the	O
Olivetti	B-Device
M20	I-Device
,	O
written	O
in	O
C	B-Language
,	O
named	O
CP/M	B-Application
-8000	I-Application
.	O
</s>
<s>
These	O
16-bit	B-Device
versions	O
of	O
CP/M	B-Application
required	O
application	O
programs	O
to	O
be	O
re-compiled	O
for	O
the	O
new	O
CPUs	O
.	O
</s>
<s>
Some	O
programs	O
written	O
in	O
assembly	B-Language
language	I-Language
could	O
be	O
automatically	O
translated	O
for	O
a	O
new	O
processor	O
.	O
</s>
<s>
One	O
tool	O
for	O
this	O
was	O
Digital	O
Research	O
's	O
XLT86	B-Operating_System
,	O
which	O
translated	O
.ASM	O
source	O
code	O
for	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
processor	O
into	O
.A86	O
source	O
code	O
for	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
.	O
</s>
<s>
The	O
translator	O
would	O
also	O
optimize	O
the	O
output	O
for	O
code	O
size	O
and	O
take	O
care	O
of	O
calling	O
conventions	O
,	O
so	O
that	O
CP/M	B-Application
-80	I-Application
and	O
MP/M	B-Operating_System
-80	I-Operating_System
programs	O
could	O
be	O
ported	O
to	O
the	O
CP/M	B-Operating_System
-86	I-Operating_System
and	O
MP/M	B-Operating_System
-86	I-Operating_System
platforms	B-Device
automatically	O
.	O
</s>
<s>
XLT86	B-Operating_System
itself	O
was	O
written	O
in	O
PL/I	B-Language
-80	O
and	O
was	O
available	O
for	O
CP/M	B-Application
-80	I-Application
platforms	B-Device
as	O
well	O
as	O
for	O
VAX/VMS	B-Operating_System
.	O
</s>
<s>
Many	O
expected	O
that	O
CP/M	B-Application
would	O
be	O
the	O
standard	O
operating	B-General_Concept
system	I-General_Concept
for	O
16-bit	B-Device
computers	I-Device
.	O
</s>
<s>
In	O
1980	O
IBM	O
approached	O
Digital	O
Research	O
,	O
at	O
Bill	O
Gates	O
 '	O
suggestion	O
,	O
to	O
license	O
a	O
forthcoming	O
version	O
of	O
CP/M	B-Application
for	O
its	O
new	O
product	O
,	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
.	O
</s>
<s>
Upon	O
the	O
failure	O
to	O
obtain	O
a	O
signed	O
non-disclosure	O
agreement	O
,	O
the	O
talks	O
failed	O
,	O
and	O
IBM	O
instead	O
contracted	O
with	O
Microsoft	O
to	O
provide	O
an	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
resulting	O
product	O
,	O
MS-DOS	B-Application
,	O
soon	O
began	O
outselling	O
CP/M	B-Application
.	O
</s>
<s>
Many	O
of	O
the	O
basic	O
concepts	O
and	O
mechanisms	O
of	O
early	O
versions	O
of	O
MS-DOS	B-Application
resembled	O
those	O
of	O
CP/M	B-Application
.	O
</s>
<s>
Internals	O
like	O
file-handling	O
data	O
structures	O
were	O
identical	O
,	O
and	O
both	O
referred	O
to	O
disk	O
drives	O
with	O
a	O
letter	O
(	O
A	O
:	O
,	O
B	O
:	O
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
MS-DOS	B-Application
'	O
s	O
main	O
innovation	O
was	O
its	O
FAT	B-Application
file	I-Application
system	I-Application
.	O
</s>
<s>
This	O
similarity	O
made	O
it	O
easier	O
to	O
port	O
popular	O
CP/M	B-Application
software	O
like	O
WordStar	B-Application
and	O
dBase	B-Application
.	O
</s>
<s>
However	O
,	O
CP/M	B-Application
'	O
s	O
concept	O
of	O
separate	O
user	O
areas	O
for	O
files	O
on	O
the	O
same	O
disk	O
was	O
never	O
ported	O
to	O
MS-DOS	B-Application
.	O
</s>
<s>
Since	O
MS-DOS	B-Application
had	O
access	O
to	O
more	O
memory	O
(	O
as	O
few	O
IBM	B-Device
PCs	I-Device
were	O
sold	O
with	O
less	O
than	O
64KB	O
of	O
memory	O
,	O
while	O
CP/M	B-Application
could	O
run	O
in	O
16KB	O
if	O
necessary	O
)	O
,	O
more	O
commands	B-Application
were	O
built	O
into	O
the	O
command-line	B-Operating_System
shell	I-Operating_System
,	O
making	O
MS-DOS	B-Application
somewhat	O
faster	O
and	O
easier	O
to	O
use	O
on	O
floppy-based	O
computers	O
.	O
</s>
<s>
Although	O
one	O
of	O
the	O
first	O
peripherals	O
for	O
the	O
IBM	B-Device
PC	I-Device
was	O
a	O
SoftCard-like	O
expansion	O
card	O
that	O
let	O
it	O
run	O
8-bit	O
CP/M	B-Application
software	O
,	O
InfoWorld	O
stated	O
in	O
1984	O
that	O
efforts	O
to	O
introduce	O
CP/M	B-Application
to	O
the	O
home	O
market	O
had	O
been	O
largely	O
unsuccessful	O
and	O
most	O
CP/M	B-Application
software	O
was	O
too	O
expensive	O
for	O
home	O
users	O
.	O
</s>
<s>
In	O
1986	O
the	O
magazine	O
stated	O
that	O
Kaypro	O
had	O
stopped	O
production	O
of	O
8-bit	O
CP/M	B-Application
-based	O
models	O
to	O
concentrate	O
on	O
sales	O
of	O
MS-DOS	B-Application
compatible	O
systems	O
,	O
long	O
after	O
most	O
other	O
vendors	O
had	O
ceased	O
production	O
of	O
new	O
equipment	O
and	O
software	O
for	O
CP/M	B-Application
.	O
</s>
<s>
CP/M	B-Application
rapidly	O
lost	O
market	O
share	O
as	O
the	O
microcomputing	B-Architecture
market	O
moved	O
to	O
the	O
IBM-compatible	O
platform	O
,	O
and	O
it	O
never	O
regained	O
its	O
former	O
popularity	O
.	O
</s>
<s>
Byte	O
magazine	O
,	O
at	O
the	O
time	O
one	O
of	O
the	O
leading	O
industry	O
magazines	O
for	O
microcomputers	B-Architecture
,	O
essentially	O
ceased	O
covering	O
CP/M	B-Application
products	O
within	O
a	O
few	O
years	O
of	O
the	O
introduction	O
of	O
the	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
For	O
example	O
,	O
in	O
1983	O
there	O
were	O
still	O
a	O
few	O
advertisements	O
for	O
S-100	O
boards	O
and	O
articles	O
on	O
CP/M	B-Application
software	O
,	O
but	O
by	O
1987	O
these	O
were	O
no	O
longer	O
found	O
in	O
the	O
magazine	O
.	O
</s>
<s>
Later	O
versions	O
of	O
CP/M	B-Operating_System
-86	I-Operating_System
made	O
significant	O
strides	O
in	O
performance	O
and	O
usability	O
and	O
were	O
made	O
compatible	O
with	O
MS-DOS	B-Application
.	O
</s>
<s>
To	O
reflect	O
this	O
compatibility	O
the	O
name	O
was	O
changed	O
,	O
and	O
CP/M	B-Operating_System
-86	I-Operating_System
became	O
DOS	B-Operating_System
Plus	I-Operating_System
,	O
which	O
in	O
turn	O
became	O
DR-DOS	B-Application
.	O
</s>
<s>
ZCPR	O
(	O
the	O
Z80	B-General_Concept
Command	O
Processor	O
Replacement	O
)	O
was	O
introduced	O
on	O
2	O
February	O
1982	O
as	O
a	O
drop-in	O
replacement	O
for	O
the	O
standard	O
Digital	O
Research	O
console	B-Application
command	I-Application
processor	O
(	O
CCP	O
)	O
and	O
was	O
initially	O
written	O
by	O
a	O
group	O
of	O
computer	O
hobbyists	O
who	O
called	O
themselves	O
"	O
The	O
CCP	O
Group	O
"	O
.	O
</s>
<s>
They	O
were	O
Frank	O
Wancho	O
,	O
Keith	O
Petersen	O
(	O
the	O
archivist	O
behind	O
Simtel	B-Application
at	O
the	O
time	O
)	O
,	O
Ron	O
Fowler	O
,	O
Charlie	O
Strom	O
,	O
Bob	O
Mathias	O
,	O
and	O
Richard	O
Conn	O
.	O
Richard	O
was	O
,	O
in	O
fact	O
,	O
the	O
driving	O
force	O
in	O
this	O
group	O
(	O
all	O
of	O
whom	O
maintained	O
contact	O
through	O
email	O
)	O
.	O
</s>
<s>
ZCPR1	O
was	O
released	O
on	O
a	O
disk	O
put	O
out	O
by	O
SIG/M	O
(	O
Special	O
Interest	O
Group/Microcomputers	O
)	O
,	O
a	O
part	O
of	O
the	O
Amateur	O
Computer	O
Club	O
of	O
New	O
Jersey	O
.	O
</s>
<s>
ZCPR2	O
was	O
upgraded	O
to	O
2.3	O
,	O
and	O
also	O
was	O
released	O
in	O
8080	B-General_Concept
code	O
,	O
permitting	O
the	O
use	O
of	O
ZCPR2	O
on	O
8080	B-General_Concept
and	O
8085	B-General_Concept
systems	O
.	O
</s>
<s>
The	O
code	O
for	O
ZCPR3	O
could	O
also	O
be	O
compiled	O
(	O
with	O
reduced	O
features	O
)	O
for	O
the	O
8080	B-General_Concept
and	O
would	O
run	O
on	O
systems	O
that	O
did	O
not	O
have	O
the	O
requisite	O
Z80	B-General_Concept
microprocessor	I-General_Concept
.	O
</s>
<s>
Features	O
of	O
ZCPR	O
as	O
of	O
version	O
3	O
included	O
shells	O
,	O
aliases	O
,	O
I/O	O
redirection	B-Device
,	O
flow	O
control	O
,	O
named	O
directories	O
,	O
search	O
paths	O
,	O
custom	O
menus	O
,	O
passwords	O
,	O
and	O
online	O
help	B-Protocol
.	O
</s>
<s>
ZCPR	O
3.3	O
no	O
longer	O
supported	O
the	O
8080	B-General_Concept
series	O
of	O
microprocessors	O
,	O
and	O
added	O
the	O
most	O
features	O
of	O
any	O
upgrade	O
in	O
the	O
ZCPR	O
line	O
.	O
</s>
<s>
While	O
enthusiastically	O
supported	O
by	O
the	O
CP/M	B-Application
user	O
base	O
of	O
the	O
time	O
,	O
ZCPR	O
alone	O
was	O
insufficient	O
to	O
slow	O
the	O
demise	O
of	O
CP/M	B-Application
.	O
</s>
<s>
A	O
minimal	O
8-bit	O
CP/M	B-Application
system	O
would	O
contain	O
the	O
following	O
components	O
:	O
</s>
<s>
The	O
NEC	B-Device
V20	I-Device
and	O
V30	B-Device
processors	O
support	O
an	O
8080-emulation	O
mode	O
that	O
can	O
run	O
8-bit	O
CP/M	B-Application
on	O
a	O
PCDOS/MS	O
-DOS	O
computer	O
so	O
equipped	O
,	O
though	O
any	O
PC	O
can	O
also	O
run	O
the	O
16-bit	B-Device
CP/M	B-Operating_System
-86	I-Operating_System
.	O
</s>
<s>
The	O
only	O
hardware	O
system	O
that	O
CP/M	B-Application
,	O
as	O
sold	O
by	O
Digital	O
Research	O
,	O
would	O
support	O
was	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
Development	O
System	O
.	O
</s>
<s>
Manufacturers	O
of	O
CP/M	B-Application
-compatible	O
systems	O
customized	O
portions	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
for	O
their	O
own	O
combination	O
of	O
installed	O
memory	O
,	O
disk	O
drives	O
,	O
and	O
console	B-Device
devices	O
.	O
</s>
<s>
CP/M	B-Application
would	O
also	O
run	O
on	O
systems	O
based	O
on	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
processor	O
since	O
the	O
Z80	B-General_Concept
was	O
compatible	O
with	O
8080	B-General_Concept
code	O
.	O
</s>
<s>
While	O
the	O
Digital	O
Research	O
distributed	O
core	O
of	O
CP/M	B-Application
(	O
BDOS	O
,	O
CCP	O
,	O
core	O
transient	O
commands	B-Application
)	O
did	O
not	O
use	O
any	O
of	O
the	O
Z80-specific	O
instructions	O
,	O
many	O
Z80-based	O
systems	O
used	O
Z80	B-General_Concept
code	O
in	O
the	O
system-specific	O
BIOS	O
,	O
and	O
many	O
applications	O
were	O
dedicated	O
to	O
Z80-based	O
CP/M	B-Application
machines	O
.	O
</s>
<s>
Digital	O
Research	O
subsequently	O
partnered	O
with	O
Zilog	O
and	O
American	O
Microsystems	O
to	O
produce	O
Personal	O
CP/M	B-Application
,	O
a	O
ROM-based	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
aimed	O
at	O
lower-cost	O
systems	O
that	O
could	O
potentially	O
be	O
equipped	O
without	O
disk	O
drives	O
.	O
</s>
<s>
First	O
featured	O
in	O
the	O
Sharp	O
MZ-800	O
,	O
a	O
cassette-based	O
system	O
with	O
optional	O
disk	O
drives	O
,	O
Personal	O
CP/M	B-Application
was	O
described	O
as	O
having	O
been	O
"	O
rewritten	O
to	O
take	O
advantage	O
of	O
the	O
enhanced	O
Z-80	B-General_Concept
instruction	O
set	O
"	O
as	O
opposed	O
to	O
preserving	O
portability	O
with	O
the	O
8080	B-General_Concept
.	O
</s>
<s>
American	O
Microsystems	O
announced	O
a	O
Z80-compatible	O
microprocessor	O
,	O
the	O
S83	O
,	O
featuring	O
8KB	O
of	O
in-package	O
ROM	B-Device
for	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
BIOS	O
,	O
together	O
with	O
comprehensive	O
logic	O
for	O
interfacing	O
with	O
64-kilobit	O
dynamic	O
RAM	B-Architecture
devices	O
.	O
</s>
<s>
On	O
most	O
machines	O
the	O
bootstrap	O
was	O
a	O
minimal	O
bootloader	B-Application
in	O
ROM	B-Device
combined	O
with	O
some	O
means	O
of	O
minimal	O
bank	B-General_Concept
switching	I-General_Concept
or	O
a	O
means	O
of	O
injecting	O
code	O
on	O
the	O
bus	O
(	O
since	O
the	O
8080	B-General_Concept
needs	O
to	O
see	O
boot	O
code	O
at	O
Address	O
0	O
for	O
start-up	O
,	O
while	O
CP/M	B-Application
needs	O
RAM	B-Architecture
there	O
)	O
;	O
for	O
others	O
,	O
this	O
bootstrap	O
had	O
to	O
be	O
entered	O
into	O
memory	O
using	O
front-panel	B-Device
controls	O
each	O
time	O
the	O
system	O
was	O
started	O
.	O
</s>
<s>
CP/M	B-Application
used	O
the	O
7-bit	B-Protocol
ASCII	I-Protocol
set	O
.	O
</s>
<s>
For	O
example	O
,	O
one	O
Kaypro	O
used	O
them	O
for	O
Greek	O
characters	O
,	O
and	O
Osborne	B-Device
machines	O
used	O
the	O
8th	O
bit	O
set	O
to	O
indicate	O
an	O
underlined	O
character	O
.	O
</s>
<s>
WordStar	B-Application
used	O
the	O
8th	O
bit	O
as	O
an	O
end-of-word	O
marker	O
.	O
</s>
<s>
International	O
CP/M	B-Application
systems	O
most	O
commonly	O
used	O
the	O
ISO	O
646	O
norm	O
for	O
localized	O
character	B-General_Concept
sets	I-General_Concept
,	O
replacing	O
certain	O
ASCII	B-Protocol
characters	I-Protocol
with	O
localized	O
characters	O
rather	O
than	O
adding	O
them	O
beyond	O
the	O
7-bit	O
boundary	O
.	O
</s>
<s>
In	O
the	O
8-bit	O
versions	O
,	O
while	O
running	O
,	O
the	O
CP/M	B-Application
operating	I-Application
system	I-Application
loaded	O
into	O
memory	O
had	O
three	O
components	O
:	O
</s>
<s>
Basic	O
Disk	O
Operating	B-General_Concept
System	I-General_Concept
(	O
BDOS	O
)	O
,	O
</s>
<s>
Console	B-Application
Command	I-Application
Processor	O
(	O
CCP	O
)	O
.	O
</s>
<s>
A	O
number	O
of	O
transient	O
commands	B-Application
for	O
standard	O
utilities	O
were	O
also	O
provided	O
.	O
</s>
<s>
The	O
transient	O
commands	B-Application
resided	O
in	O
files	O
with	O
the	O
extension	O
.COM	O
on	O
disk	O
.	O
</s>
<s>
The	O
BDOS	O
implemented	O
the	O
CP/M	B-Application
file	B-Application
system	I-Application
and	O
some	O
input/output	O
abstractions	O
(	O
such	O
as	O
redirection	B-Device
)	O
on	O
top	O
of	O
the	O
BIOS	O
.	O
</s>
<s>
The	O
CCP	O
took	O
user	O
commands	B-Application
and	O
either	O
executed	O
them	O
directly	O
(	O
internal	O
commands	B-Application
such	O
as	O
DIR	B-Device
to	O
show	O
a	O
directory	O
or	O
ERA	B-Device
to	O
delete	B-Device
a	O
file	B-Operating_System
)	O
or	O
loaded	O
and	O
started	O
an	O
executable	O
file	B-Operating_System
of	O
the	O
given	O
name	O
(	O
transient	O
commands	B-Application
such	O
as	O
PIP.COM	B-Application
to	O
copy	O
files	O
or	O
STAT.COM	O
to	O
show	O
various	O
file	B-Operating_System
and	O
system	O
information	O
)	O
.	O
</s>
<s>
Third-party	O
applications	O
for	O
CP/M	B-Application
were	O
also	O
essentially	O
transient	O
commands	B-Application
.	O
</s>
<s>
The	O
BDOS	O
,	O
CCP	O
and	O
standard	O
transient	O
commands	B-Application
were	O
the	O
same	O
in	O
all	O
installations	O
of	O
a	O
particular	O
revision	O
of	O
CP/M	B-Application
,	O
but	O
the	O
BIOS	O
portion	O
was	O
always	O
adapted	O
to	O
the	O
particular	O
hardware	O
.	O
</s>
<s>
Adding	O
memory	O
to	O
a	O
computer	O
,	O
for	O
example	O
,	O
meant	O
that	O
the	O
CP/M	B-Application
system	O
had	O
to	O
be	O
reinstalled	O
to	O
allow	O
transient	O
programs	O
to	O
use	O
the	O
additional	O
memory	O
space	O
.	O
</s>
<s>
The	O
utility	O
program	O
adjusted	O
the	O
addresses	O
in	O
absolute	O
jump	O
and	O
subroutine	O
call	O
instructions	O
to	O
new	O
addresses	O
required	O
by	O
the	O
new	O
location	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
in	O
processor	O
memory	O
.	O
</s>
<s>
Once	O
installed	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
(	O
BIOS	O
,	O
BDOS	O
and	O
CCP	O
)	O
was	O
stored	O
in	O
reserved	O
areas	O
at	O
the	O
beginning	O
of	O
any	O
disk	O
which	O
would	O
be	O
used	O
to	O
boot	O
the	O
system	O
.	O
</s>
<s>
On	O
start-up	O
,	O
the	O
bootloader	B-Application
(	O
usually	O
contained	O
in	O
a	O
ROM	B-Device
firmware	O
chip	O
)	O
would	O
load	O
the	O
operating	B-General_Concept
system	I-General_Concept
from	O
the	O
disk	O
in	O
drive	O
A	O
:	O
.	O
</s>
<s>
By	O
modern	O
standards	O
CP/M	B-Application
was	O
primitive	O
,	O
owing	O
to	O
the	O
extreme	O
constraints	O
on	O
program	O
size	O
.	O
</s>
<s>
The	O
majority	O
of	O
the	O
complexity	O
in	O
CP/M	B-Application
was	O
isolated	O
in	O
the	O
BDOS	O
,	O
and	O
to	O
a	O
lesser	O
extent	O
,	O
the	O
CCP	O
and	O
transient	O
commands	B-Application
.	O
</s>
<s>
This	O
meant	O
that	O
by	O
porting	O
the	O
limited	O
number	O
of	O
simple	O
routines	O
in	O
the	O
BIOS	O
to	O
a	O
particular	O
hardware	B-Device
platform	I-Device
,	O
the	O
entire	O
OS	O
would	O
work	O
.	O
</s>
<s>
This	O
significantly	O
reduced	O
the	O
development	O
time	O
needed	O
to	O
support	O
new	O
machines	O
,	O
and	O
was	O
one	O
of	O
the	O
main	O
reasons	O
for	O
CP/M	B-Application
'	O
s	O
widespread	O
use	O
.	O
</s>
<s>
Today	O
this	O
sort	O
of	O
abstraction	O
is	O
common	O
to	O
most	O
OSs	O
(	O
a	O
hardware	B-Operating_System
abstraction	I-Operating_System
layer	I-Operating_System
)	O
,	O
but	O
at	O
the	O
time	O
of	O
CP/M	B-Application
'	O
s	O
birth	O
,	O
OSs	O
were	O
typically	O
intended	O
to	O
run	O
on	O
only	O
one	O
machine	O
platform	O
,	O
and	O
multilayer	O
designs	O
were	O
considered	O
unnecessary	O
.	O
</s>
<s>
The	O
Console	B-Application
Command	I-Application
Processor	O
,	O
or	O
CCP	O
,	O
accepted	O
input	O
from	O
the	O
keyboard	O
and	O
conveyed	O
results	O
to	O
the	O
terminal	O
.	O
</s>
<s>
CP/M	B-Application
itself	O
would	O
work	O
with	O
either	O
a	O
printing	O
terminal	O
or	O
a	O
video	B-General_Concept
terminal	I-General_Concept
.	O
</s>
<s>
All	O
CP/M	B-Application
commands	B-Application
had	O
to	O
be	O
typed	O
in	O
on	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
The	O
console	B-Device
would	O
most	O
often	O
display	O
the	O
A>	O
prompt	O
,	O
to	O
indicate	O
the	O
current	O
default	O
disk	O
drive	O
.	O
</s>
<s>
When	O
used	O
with	O
a	O
video	B-General_Concept
terminal	I-General_Concept
,	O
this	O
would	O
usually	O
be	O
followed	O
by	O
a	O
blinking	O
cursor	B-Application
supplied	O
by	O
the	O
terminal	O
.	O
</s>
<s>
CP/M	B-Application
'	O
s	O
command-line	B-Application
interface	I-Application
was	O
patterned	O
after	O
the	O
operating	B-General_Concept
systems	I-General_Concept
from	O
Digital	O
Equipment	O
,	O
such	O
as	O
RT-11	B-Operating_System
for	O
the	O
PDP-11	B-Device
and	O
OS/8	B-Operating_System
for	O
the	O
PDP-8	B-Device
.	O
</s>
<s>
Commands	B-Application
took	O
the	O
form	O
of	O
a	O
keyword	O
followed	O
by	O
a	O
list	O
of	O
parameters	O
separated	O
by	O
spaces	O
or	O
special	O
characters	O
.	O
</s>
<s>
Otherwise	O
it	O
would	O
attempt	O
to	O
find	O
an	O
executable	O
file	B-Operating_System
on	O
the	O
currently	O
logged	O
disk	O
drive	O
and	O
(	O
in	O
later	O
versions	O
)	O
user	O
area	O
,	O
load	O
it	O
,	O
and	O
pass	O
it	O
any	O
additional	O
parameters	O
from	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
On	O
completion	O
,	O
CP/M	B-Application
would	O
reload	O
the	O
part	O
of	O
the	O
CCP	O
that	O
had	O
been	O
overwritten	O
by	O
application	O
programs	O
—	O
this	O
allowed	O
transient	O
programs	O
a	O
larger	O
memory	O
space	O
.	O
</s>
<s>
The	O
commands	B-Application
themselves	O
could	O
sometimes	O
be	O
obscure	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
command	O
to	O
duplicate	O
files	O
was	O
named	O
PIP	B-Application
(	O
Peripheral-Interchange-Program	O
)	O
,	O
the	O
name	O
of	O
the	O
old	O
DEC	O
utility	O
used	O
for	O
that	O
purpose	O
.	O
</s>
<s>
The	O
format	O
of	O
parameters	O
given	O
to	O
a	O
program	O
was	O
not	O
standardized	O
,	O
so	O
that	O
there	O
was	O
no	O
single	O
option	O
character	O
that	O
differentiated	O
options	O
from	O
file	B-Operating_System
names	O
.	O
</s>
<s>
The	O
CP/M	B-Application
Console	B-Application
Command	I-Application
Processor	O
includes	O
DIR	B-Device
,	O
ERA	B-Device
,	O
REN	B-Device
,	O
SAVE	O
,	O
TYPE	B-Device
,	O
and	O
USER	O
as	O
built-in	O
commands	B-Application
.	O
</s>
<s>
Transient	O
commands	B-Application
in	O
CP/M	B-Application
include	O
ASM	B-Application
,	O
DDT	B-Operating_System
,	O
DUMP	O
,	O
ED	O
,	O
LOAD	O
,	O
,	O
PIP	B-Application
,	O
STAT	O
,	O
SUBMIT	O
,	O
and	O
SYSGEN	O
.	O
</s>
<s>
CP/M	B-Application
Plus	O
(	O
CP/M	B-Application
Version	O
3	O
)	O
includes	O
DIR	B-Device
(	O
display	O
list	O
of	O
files	O
from	O
a	O
directory	O
except	O
those	O
marked	O
with	O
the	O
SYS	O
attribute	O
)	O
,	O
DIRSYS	B-Device
/	O
DIRS	B-Device
(	O
list	O
files	O
marked	O
with	O
the	O
SYS	O
attribute	O
in	O
the	O
directory	O
)	O
,	O
ERASE	B-Device
/	O
ERA	B-Device
(	O
delete	B-Device
a	O
file	B-Operating_System
)	O
,	O
RENAME	B-Device
/	O
REN	B-Device
(	O
rename	B-Device
a	O
file	B-Operating_System
)	O
,	O
TYPE	B-Device
/	O
TYP	O
(	O
display	O
contents	O
of	O
an	O
ASCII	B-Protocol
character	I-Protocol
file	B-Operating_System
)	O
,	O
and	O
USER	O
/	O
USE	O
(	O
change	O
user	O
number	O
)	O
as	O
built-in	O
commands	B-Application
:	O
CP/M	B-Application
3	O
allows	O
the	O
user	O
to	O
abbreviate	O
the	O
built-in	O
commands	B-Application
.	O
</s>
<s>
Transient	O
commands	B-Application
in	O
CP/M	B-Application
3	O
include	O
COPYSYS	O
,	O
DATE	O
,	O
DEVICE	O
,	O
DUMP	O
,	O
ED	O
,	O
GET	O
,	O
HELP	B-Protocol
,	O
HEXCOM	O
,	O
INITDIR	O
,	O
LINK	O
,	O
MAC	O
,	O
PIP	B-Application
,	O
PUT	O
,	O
RMAC	O
,	O
SET	O
,	O
SETDEF	O
,	O
SHOW	O
,	O
SID	O
,	O
SUBMIT	O
,	O
and	O
XREF	O
.	O
</s>
<s>
The	O
Basic	O
Disk	O
Operating	B-General_Concept
System	I-General_Concept
,	O
or	O
BDOS	O
,	O
provided	O
access	O
to	O
such	O
operations	O
as	O
opening	O
a	O
file	B-Operating_System
,	O
output	O
to	O
the	O
console	B-Device
,	O
or	O
printing	O
.	O
</s>
<s>
Since	O
the	O
address	O
was	O
the	O
same	O
independent	O
of	O
the	O
amount	O
of	O
memory	O
in	O
the	O
system	O
,	O
application	O
programs	O
would	O
run	O
the	O
same	O
way	O
for	O
any	O
type	B-Device
or	O
configuration	O
of	O
hardware	O
.	O
</s>
<s>
The	O
Basic	O
Input	O
Output	O
System	O
or	O
BIOS	O
,	O
provided	O
the	O
lowest	O
level	O
functions	O
required	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
These	O
included	O
reading	O
or	O
writing	O
single	O
characters	O
to	O
the	O
system	B-Device
console	I-Device
and	O
reading	O
or	O
writing	O
a	O
sector	O
of	O
data	O
from	O
the	O
disk	O
.	O
</s>
<s>
The	O
BDOS	O
handled	O
some	O
of	O
the	O
buffering	O
of	O
data	O
from	O
the	O
diskette	B-Device
,	O
but	O
before	O
CP/M3.0	O
it	O
assumed	O
a	O
disk	O
sector	O
size	O
fixed	O
at	O
128	O
bytes	O
,	O
as	O
used	O
on	O
single-density	O
8-inch	B-Device
floppy	I-Device
disks	O
.	O
</s>
<s>
For	O
example	O
,	O
some	O
manufacturers	O
used	O
a	O
separate	O
computer	B-General_Concept
terminal	I-General_Concept
,	O
while	O
others	O
designed	O
a	O
built-in	O
integrated	O
video	O
display	O
system	O
.	O
</s>
<s>
Serial	O
ports	O
for	O
printers	O
and	O
modems	B-Application
could	O
use	O
different	O
types	O
of	O
UART	O
chips	O
,	O
and	O
port	O
addresses	O
were	O
not	O
fixed	O
.	O
</s>
<s>
Some	O
machines	O
used	O
memory-mapped	O
I/O	O
instead	O
of	O
the	O
8080	B-General_Concept
I/O	O
address	O
space	O
.	O
</s>
<s>
All	O
of	O
these	O
variations	O
in	O
the	O
hardware	O
were	O
concealed	O
from	O
other	O
modules	O
of	O
the	O
system	O
by	O
use	O
of	O
the	O
BIOS	O
,	O
which	O
used	O
standard	O
entry	O
points	O
for	O
the	O
services	O
required	O
to	O
run	O
CP/M	B-Application
such	O
as	O
character	O
I/O	O
or	O
accessing	O
a	O
disk	O
block	O
.	O
</s>
<s>
Since	O
support	O
for	O
serial	O
communication	O
to	O
a	O
modem	B-Application
was	O
very	O
rudimentary	O
in	O
the	O
BIOS	O
or	O
may	O
have	O
been	O
absent	O
altogether	O
,	O
it	O
was	O
common	O
practice	O
for	O
CP/M	B-Application
programs	O
that	O
used	O
modems	B-Application
to	O
have	O
a	O
user-installed	O
overlay	O
containing	O
all	O
the	O
code	O
required	O
to	O
access	O
a	O
particular	O
machine	O
's	O
serial	O
port	O
.	O
</s>
<s>
WordStar	B-Application
,	O
one	O
of	O
the	O
first	O
widely	O
used	O
word	B-General_Concept
processors	I-General_Concept
,	O
and	O
dBase	B-Application
,	O
an	O
early	O
and	O
popular	O
database	O
program	O
for	O
microcomputers	B-Architecture
,	O
were	O
originally	O
written	O
for	O
CP/M	B-Application
.	O
</s>
<s>
Two	O
early	O
outliners	B-Application
,	O
KAMAS	B-Application
(	O
Knowledge	O
and	O
Mind	O
Amplification	O
System	O
)	O
and	O
its	O
cut-down	O
successor	O
Out-Think	O
(	O
without	O
programming	O
facilities	O
and	O
retooled	O
for	O
8080/V20	O
compatibility	O
)	O
were	O
also	O
written	O
for	O
CP/M	B-Application
,	O
though	O
later	O
rewritten	O
for	O
MS-DOS	B-Application
.	O
</s>
<s>
Turbo	B-Application
Pascal	I-Application
,	O
the	O
ancestor	O
of	O
Borland	B-Language
Delphi	I-Language
,	O
and	O
Multiplan	B-Device
,	O
the	O
ancestor	O
of	O
Microsoft	B-Application
Excel	I-Application
,	O
also	O
debuted	O
on	O
CP/M	B-Application
before	O
MS-DOS	B-Application
versions	O
became	O
available	O
.	O
</s>
<s>
VisiCalc	B-Application
,	O
the	O
first-ever	O
spreadsheet	O
program	O
,	O
was	O
made	O
available	O
for	O
CP/M	B-Application
.	O
</s>
<s>
Another	O
company	O
,	O
Sorcim	O
,	O
created	O
its	O
SuperCalc	B-Application
spreadsheet	O
for	O
CP/M	B-Application
,	O
which	O
would	O
go	O
on	O
to	O
become	O
the	O
market	O
leader	O
and	O
de	O
facto	O
standard	O
on	O
CP/M	B-Application
.	O
</s>
<s>
Supercalc	B-Application
would	O
go	O
on	O
to	O
be	O
a	O
competitor	O
in	O
the	O
spreadsheet	O
market	O
in	O
the	O
MS-DOS	B-Application
world	O
.	O
</s>
<s>
AutoCAD	B-Algorithm
,	O
a	O
CAD	O
application	O
from	O
Autodesk	O
debuted	O
on	O
CP/M	B-Application
.	O
</s>
<s>
A	O
host	O
of	O
compilers	O
and	O
interpreters	O
for	O
popular	O
programming	O
languages	O
of	O
the	O
time	O
(	O
such	O
as	O
BASIC	O
,	O
Borland	O
's	O
Turbo	B-Application
Pascal	I-Application
,	O
FORTRAN	B-Application
and	O
even	O
PL/I	B-Language
)	O
were	O
available	O
,	O
among	O
them	O
several	O
of	O
the	O
earliest	O
Microsoft	O
products	O
.	O
</s>
<s>
CP/M	B-Application
software	O
often	O
came	O
with	O
installers	B-Operating_System
that	O
adapted	O
it	O
to	O
a	O
wide	O
variety	O
of	O
computers	O
.	O
</s>
<s>
The	O
source	O
code	O
for	O
BASIC	O
programs	O
was	O
easily	O
accessible	O
,	O
and	O
most	O
forms	O
of	O
copy	B-Application
protection	I-Application
were	O
ineffective	O
on	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
A	O
Kaypro	O
II	O
owner	O
,	O
for	O
example	O
,	O
would	O
obtain	O
software	O
on	O
Xerox	B-Device
820	I-Device
format	O
,	O
then	O
copy	O
it	O
to	O
and	O
run	O
it	O
from	O
Kaypro-format	O
disks	O
.	O
</s>
<s>
The	O
lack	O
of	O
standardized	O
graphics	O
support	O
limited	O
video	O
games	O
,	O
but	O
various	O
character	O
and	O
text-based	O
games	O
were	O
ported	O
,	O
such	O
as	O
Telengard	B-Application
,	O
Gorillas	B-Application
,	O
Hamurabi	B-Application
,	O
Lunar	B-Application
Lander	I-Application
,	O
along	O
with	O
early	O
interactive	O
fiction	O
including	O
the	O
Zork	B-Application
series	O
and	O
Colossal	B-Application
Cave	I-Application
Adventure	I-Application
.	O
</s>
<s>
Text	O
adventure	B-Application
specialist	O
Infocom	O
was	O
one	O
of	O
the	O
few	O
publishers	O
to	O
consistently	O
release	O
their	O
games	O
in	O
CP/M	B-Application
format	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
was	O
XMODEM	B-Protocol
,	O
which	O
allowed	O
reliable	O
file	B-Operating_System
transfers	O
via	O
modem	B-Application
and	O
phone	O
line	O
.	O
</s>
<s>
Another	O
program	O
native	O
to	O
CP/M	B-Application
was	O
the	O
outline	B-Application
processor	I-Application
KAMAS	B-Application
.	O
</s>
<s>
The	O
read/write	O
memory	O
between	O
address	O
0100	O
hexadecimal	O
and	O
the	O
lowest	O
address	O
of	O
the	O
BDOS	O
was	O
the	O
Transient	O
Program	O
Area	O
(	O
TPA	O
)	O
available	O
for	O
CP/M	B-Application
application	O
programs	O
.	O
</s>
<s>
Although	O
all	O
Z80	B-General_Concept
and	O
8080	B-General_Concept
processors	O
could	O
address	O
64	O
kilobytes	O
of	O
memory	O
,	O
the	O
amount	O
available	O
for	O
application	O
programs	O
could	O
vary	O
,	O
depending	O
on	O
the	O
design	O
of	O
the	O
particular	O
computer	O
.	O
</s>
<s>
Bank	B-General_Concept
switching	I-General_Concept
was	O
a	O
common	O
technique	O
that	O
allowed	O
systems	O
to	O
have	O
a	O
large	O
TPA	O
while	O
switching	O
out	O
ROM	B-Device
or	O
video	O
memory	O
space	O
as	O
needed	O
.	O
</s>
<s>
CP/M	B-Application
came	O
with	O
a	O
Dynamic	O
Debugging	O
Tool	O
,	O
nicknamed	O
DDT	B-Operating_System
(	O
after	O
the	O
insecticide	O
,	O
i.e.	O
</s>
<s>
a	O
bug-killer	O
)	O
,	O
which	O
allowed	O
memory	O
and	O
program	O
modules	O
to	O
be	O
examined	O
and	O
manipulated	O
,	O
and	O
allowed	O
a	O
program	O
to	O
be	O
executed	O
one	O
step	O
at	O
a	O
time	O
.	O
</s>
<s>
CP/M	B-Application
originally	O
did	O
not	O
support	O
the	O
equivalent	O
of	O
terminate	O
and	O
stay	O
resident	O
(	O
TSR	O
)	O
programs	O
as	O
under	O
DOS	B-Device
.	O
</s>
<s>
Programmers	O
could	O
write	O
software	O
that	O
could	O
intercept	O
certain	O
operating	B-General_Concept
system	I-General_Concept
calls	O
and	O
extend	O
or	O
alter	O
their	O
functionality	O
.	O
</s>
<s>
Using	O
this	O
capability	O
,	O
programmers	O
developed	O
and	O
sold	O
auxiliary	O
desk	B-Application
accessory	I-Application
programs	O
,	O
such	O
as	O
SmartKey	B-Application
,	O
a	O
keyboard	O
utility	O
to	O
assign	O
any	O
string	O
of	O
bytes	O
to	O
any	O
key	O
.	O
</s>
<s>
CP/M3	O
,	O
however	O
,	O
added	O
support	O
for	O
dynamically	B-Operating_System
loadable	I-Operating_System
Resident	O
System	O
Extensions	O
(	O
RSX	O
)	O
.	O
</s>
<s>
A	O
so-called	O
null	O
command	O
file	B-Operating_System
could	O
be	O
used	O
to	O
allow	O
CCP	O
to	O
load	O
an	O
RSX	O
without	O
a	O
transient	O
program	O
.	O
</s>
<s>
Although	O
CP/M	B-Application
provided	O
some	O
hardware	B-Operating_System
abstraction	I-Operating_System
to	O
standardize	O
the	O
interface	O
to	O
disk	O
I/O	O
or	O
console	B-Device
I/O	O
,	O
application	O
programs	O
still	O
typically	O
required	O
installation	O
to	O
make	O
use	O
of	O
all	O
the	O
features	O
of	O
such	O
equipment	O
as	O
printers	O
and	O
terminals	B-General_Concept
.	O
</s>
<s>
This	O
procedure	O
was	O
not	O
defined	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
;	O
a	O
user	O
would	O
typically	O
run	O
an	O
installation	O
program	O
that	O
would	O
either	O
allow	O
selection	O
from	O
a	O
range	O
of	O
devices	O
,	O
or	O
else	O
allow	O
feature-by-feature	O
editing	O
of	O
the	O
escape	O
sequences	O
required	O
to	O
access	O
a	O
function	O
.	O
</s>
<s>
This	O
had	O
to	O
be	O
repeated	O
for	O
each	O
application	O
program	O
,	O
since	O
there	O
was	O
no	O
central	O
operating	B-General_Concept
system	I-General_Concept
service	O
provided	O
for	O
these	O
devices	O
.	O
</s>
<s>
To	O
use	O
a	O
program	O
such	O
as	O
Wordstar	B-Application
with	O
more	O
than	O
one	O
printer	O
(	O
say	O
,	O
a	O
fast	O
dot-matrix	O
printer	O
or	O
a	O
slower	O
but	O
presentation-quality	O
daisy	O
wheel	O
printer	O
)	O
,	O
a	O
separate	O
version	O
of	O
Wordstar	B-Application
had	O
to	O
be	O
prepared	O
,	O
and	O
one	O
had	O
to	O
load	O
the	O
Wordstar	B-Application
version	O
that	O
corresponded	O
to	O
the	O
printer	O
selected	O
(	O
and	O
exiting	O
and	O
reloading	O
to	O
change	O
printers	O
)	O
.	O
</s>
<s>
IBM	B-Device
System/34	I-Device
and	O
IBM	B-Device
3740	I-Device
's	O
single-density	O
,	O
single-sided	O
format	O
is	O
CP/M	B-Application
'	O
s	O
standard	O
8-inch	O
floppy-disk	O
format	O
.	O
</s>
<s>
No	O
standard	O
5.25-inch	O
CP/M	B-Application
disk	O
format	O
exists	O
,	O
with	O
Kaypro	O
,	O
Morrow	O
Designs	O
,	O
Osborne	B-Device
,	O
and	O
others	O
each	O
using	O
their	O
own	O
.	O
</s>
<s>
JRT	B-Language
Pascal	I-Language
,	O
for	O
example	O
,	O
provided	O
versions	O
on	O
5.25-inch	O
disk	O
for	O
North	O
Star	O
,	O
Osborne	B-Device
,	O
Apple	O
,	O
Heath	O
hard	B-Architecture
sector	I-Architecture
and	O
soft	O
sector	O
,	O
and	O
Superbrain	B-Operating_System
,	O
and	O
one	O
8-inch	O
version	O
.	O
</s>
<s>
Ellis	O
Computing	O
also	O
offered	O
its	O
software	O
for	O
both	O
Heath	O
formats	O
,	O
and	O
16	O
other	O
5.25-inch	O
formats	O
including	O
two	O
different	O
TRS-80	B-Device
CP/M	B-Application
modifications	O
.	O
</s>
<s>
Most	O
software	O
was	O
available	O
in	O
the	O
Xerox	B-Device
820	I-Device
format	O
,	O
and	O
other	O
computers	O
such	O
as	O
the	O
Kaypro	O
II	O
were	O
compatible	O
with	O
it	O
.	O
</s>
<s>
No	O
single	O
manufacturer	O
,	O
however	O
,	O
prevailed	O
in	O
the	O
5.25-inch	O
era	B-Device
of	O
CP/M	B-Application
use	O
,	O
and	O
disk	O
formats	O
were	O
often	O
not	O
portable	O
between	O
hardware	O
manufacturers	O
.	O
</s>
<s>
Because	O
of	O
this	O
situation	O
,	O
disk	O
format	O
translation	O
programs	O
,	O
which	O
allowed	O
a	O
machine	O
to	O
read	O
many	O
different	O
formats	O
,	O
became	O
popular	O
and	O
reduced	O
the	O
confusion	O
,	O
as	O
did	O
programs	O
like	O
Kermit	B-Protocol
,	O
which	O
allowed	O
transfer	O
of	O
data	O
and	O
programs	O
from	O
one	O
machine	O
to	O
another	O
using	O
the	O
serial	O
ports	O
that	O
most	O
CP/M	B-Application
machines	O
had	O
.	O
</s>
<s>
CP/M	B-Application
supported	O
options	O
to	O
control	O
the	O
size	O
of	O
reserved	O
and	O
directory	O
areas	O
on	O
the	O
disk	O
,	O
and	O
the	O
mapping	O
between	O
logical	O
disk	O
sectors	O
(	O
as	O
seen	O
by	O
CP/M	B-Application
programs	O
)	O
and	O
physical	O
sectors	O
as	O
allocated	O
on	O
the	O
disk	O
.	O
</s>
<s>
The	O
degree	O
of	O
portability	O
between	O
different	O
CP/M	B-Application
machines	O
depended	O
on	O
the	O
type	B-Device
of	O
disk	O
drive	O
and	O
controller	O
used	O
since	O
many	O
different	O
floppy	B-Device
types	O
existed	O
in	O
the	O
CP/M	B-Application
era	B-Device
in	O
both	O
8-inch	O
and	O
5.25-inch	O
format	O
.	O
</s>
<s>
Disks	O
could	O
be	O
hard	O
or	O
soft	B-Device
sectored	I-Device
,	O
single	O
or	O
double	O
density	O
,	O
single	O
or	O
double	O
sided	O
,	O
35	O
track	O
,	O
40	O
track	O
,	O
77	O
track	O
,	O
or	O
80	O
track	O
,	O
and	O
the	O
sector	O
layout	O
,	O
size	O
and	O
interleave	O
could	O
vary	O
widely	O
as	O
well	O
.	O
</s>
<s>
Although	O
translation	O
programs	O
could	O
allow	O
the	O
user	O
to	O
read	O
disk	O
types	O
from	O
different	O
machines	O
,	O
the	O
drive	O
type	B-Device
and	O
controller	O
were	O
also	O
factors	O
.	O
</s>
<s>
By	O
1982	O
,	O
soft-sector	O
,	O
single-sided	O
,	O
40-track	O
5.25-inch	O
disks	O
had	O
become	O
the	O
most	O
popular	O
format	O
to	O
distribute	O
CP/M	B-Application
software	O
on	O
as	O
they	O
were	O
used	O
by	O
the	O
most	O
common	O
consumer-level	O
machines	O
of	O
that	O
time	O
,	O
such	O
as	O
the	O
Apple	O
II	O
,	O
TRS-80	B-Device
,	O
Osborne	B-Device
1	I-Device
,	O
Kaypro	O
II	O
,	O
and	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
A	O
translation	O
program	O
allowed	O
the	O
user	O
to	O
read	O
any	O
disks	O
on	O
his	O
machine	O
that	O
had	O
a	O
similar	O
format	O
—	O
for	O
example	O
,	O
the	O
Kaypro	O
II	O
could	O
read	O
TRS-80	B-Device
,	O
Osborne	B-Device
,	O
IBM	B-Device
PC	I-Device
,	O
and	O
Epson	B-Device
disks	O
.	O
</s>
<s>
The	O
first	O
half	O
of	O
double-sided	O
disks	O
(	O
like	O
those	O
of	O
the	O
Epson	B-Device
QX-10	I-Device
)	O
could	O
be	O
read	O
because	O
CP/M	B-Application
accessed	O
disk	O
tracks	O
sequentially	O
with	O
track	O
0	O
being	O
the	O
first	O
(	O
outermost	O
)	O
track	O
of	O
side	O
1	O
and	O
track	O
79	O
(	O
on	O
a	O
40-track	O
disk	O
)	O
being	O
the	O
last	O
(	O
innermost	O
)	O
track	O
of	O
side	O
2	O
.	O
</s>
<s>
Apple	O
II	O
users	O
were	O
unable	O
to	O
use	O
anything	O
but	O
Apple	O
's	O
GCR	O
format	O
and	O
so	O
had	O
to	O
obtain	O
CP/M	B-Application
software	O
on	O
Apple	O
format	O
disks	O
or	O
else	O
transfer	O
it	O
via	O
serial	O
link	O
.	O
</s>
<s>
The	O
fragmented	O
CP/M	B-Application
market	O
,	O
requiring	O
distributors	O
either	O
to	O
stock	O
multiple	O
formats	O
of	O
disks	O
or	O
to	O
invest	O
in	O
multiformat	O
duplication	O
equipment	O
,	O
compared	O
with	O
the	O
more	O
standardized	O
IBM	B-Device
PC	I-Device
disk	O
formats	O
,	O
was	O
a	O
contributing	O
factor	O
to	O
the	O
rapid	O
obsolescence	O
of	O
CP/M	B-Application
after	O
1981	O
.	O
</s>
<s>
One	O
of	O
the	O
last	O
notable	O
CP/M	B-Application
-capable	O
machines	O
to	O
appear	O
was	O
the	O
Commodore	O
128	O
in	O
1985	O
,	O
which	O
had	O
a	O
Z80	B-General_Concept
for	O
CP/M	B-Application
support	O
in	O
addition	O
to	O
its	O
native	O
mode	O
using	O
a	O
6502-derivative	O
CPU	O
.	O
</s>
<s>
Using	O
CP/M	B-Application
required	O
either	O
a	O
1571	B-Device
or	O
1581	O
disk	O
drive	O
which	O
could	O
read	O
soft-sector	O
40-track	O
MFM-format	O
disks	O
.	O
</s>
<s>
The	O
first	O
computer	O
to	O
use	O
a	O
3.5-inch	O
floppy	B-Device
drive	I-Device
,	O
the	O
Sony	O
SMC-70	O
,	O
ran	O
CP/M2.2	O
.	O
</s>
<s>
The	O
Commodore	B-Device
128	I-Device
,	O
Bondwell-2	B-Operating_System
laptop	O
,	O
Micromint/Ciarcia	O
SB-180	O
,	O
MSX	B-Operating_System
and	O
TRS-80	B-Device
Model	O
4	O
(	O
running	O
Montezuma	O
CP/M2.2	O
)	O
also	O
supported	O
the	O
use	O
of	O
CP/M	B-Application
with	O
3.5-inch	O
floppy	B-Device
disks	I-Device
.	O
</s>
<s>
CP/AM	O
,	O
Applied	O
Engineering	O
's	O
version	O
of	O
CP/M	B-Application
for	O
the	O
Apple	O
II	O
,	O
also	O
supported	O
3.5-inch	O
disks	O
(	O
as	O
well	O
as	O
RAM	B-Architecture
disks	O
on	O
RAM	B-Architecture
cards	O
compatible	O
with	O
the	O
Apple	O
II	O
Memory	O
Expansion	O
Card	O
)	O
.	O
</s>
<s>
The	O
Amstrad	B-Device
PCW	I-Device
ran	O
CP/M	B-Application
using	O
3-inch	O
floppy	B-Device
drives	I-Device
at	O
first	O
,	O
and	O
later	O
switched	O
to	O
the	O
3.5	O
inch	O
drives	O
.	O
</s>
<s>
File	B-Operating_System
names	O
were	O
specified	O
as	O
a	O
string	O
of	O
up	O
to	O
eight	O
characters	O
,	O
followed	O
by	O
a	O
period	O
,	O
followed	O
by	O
a	O
file	B-Operating_System
name	O
extension	O
of	O
up	O
to	O
three	O
characters	O
(	O
"	O
8.3	O
"	O
filename	O
format	O
)	O
.	O
</s>
<s>
The	O
extension	O
usually	O
identified	O
the	O
type	B-Device
of	O
the	O
file	B-Operating_System
.	O
</s>
<s>
For	O
example	O
,	O
.COM	O
indicated	O
an	O
executable	O
program	O
file	B-Operating_System
,	O
and	O
.TXT	B-General_Concept
indicated	O
a	O
file	B-Operating_System
containing	O
ASCII	B-Protocol
text	I-Protocol
.	O
</s>
<s>
Characters	O
in	O
filenames	O
entered	O
at	O
the	O
command	O
prompt	O
were	O
converted	O
to	O
upper	O
case	O
,	O
but	O
this	O
was	O
not	O
enforced	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Programs	O
(	O
MBASIC	B-Language
is	O
a	O
notable	O
example	O
)	O
were	O
able	O
to	O
create	O
filenames	O
containing	O
lower-case	O
letters	O
,	O
which	O
then	O
could	O
not	O
easily	O
be	O
referenced	O
at	O
the	O
command	B-Application
line	I-Application
.	O
</s>
<s>
To	O
refer	O
to	O
a	O
file	B-Operating_System
on	O
a	O
specific	O
drive	O
,	O
the	O
drive	O
letter	O
was	O
prefixed	O
to	O
the	O
file	B-Operating_System
name	O
,	O
separated	O
by	O
a	O
colon	O
,	O
e.g.	O
,	O
A:FILE.TXT	O
.	O
</s>
<s>
File	B-Operating_System
size	O
was	O
specified	O
as	O
the	O
number	O
of	O
128-byte	O
records	O
(	O
directly	O
corresponding	O
to	O
disk	O
sectors	O
on	O
8-inch	O
drives	O
)	O
occupied	O
by	O
a	O
file	B-Operating_System
on	O
the	O
disk	O
.	O
</s>
<s>
There	O
was	O
no	O
generally	O
supported	O
way	O
of	O
specifying	O
byte-exact	O
file	B-Operating_System
sizes	O
.	O
</s>
<s>
The	O
current	O
size	O
of	O
a	O
file	B-Operating_System
was	O
maintained	O
in	O
the	O
file	B-Operating_System
's	O
File	B-Operating_System
Control	I-Operating_System
Block	I-Operating_System
(	O
FCB	O
)	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Since	O
many	O
application	O
programs	O
(	O
such	O
as	O
text	B-Application
editors	I-Application
)	O
prefer	O
to	O
deal	O
with	O
files	O
as	O
sequences	O
of	O
characters	O
rather	O
than	O
as	O
sequences	O
of	O
records	O
,	O
by	O
convention	O
text	B-General_Concept
files	I-General_Concept
were	O
terminated	O
with	O
a	O
control-Z	O
character	O
(	O
ASCII	B-Protocol
SUB	O
,	O
hexadecimal	O
1A	O
)	O
.	O
</s>
<s>
Determining	O
the	O
end	B-Language
of	O
a	O
text	B-General_Concept
file	I-General_Concept
therefore	O
involved	O
examining	O
the	O
last	O
record	O
of	O
the	O
file	B-Operating_System
to	O
locate	O
the	O
terminating	O
control-Z	O
.	O
</s>
<s>
This	O
also	O
meant	O
that	O
inserting	O
a	O
control-Z	O
character	O
into	O
the	O
middle	O
of	O
a	O
file	B-Operating_System
usually	O
had	O
the	O
effect	O
of	O
truncating	O
the	O
text	O
contents	O
of	O
the	O
file	B-Operating_System
.	O
</s>
<s>
With	O
the	O
advent	B-Application
of	O
larger	O
removable	O
and	O
fixed	B-Device
disk	I-Device
drives	I-Device
,	O
disk	O
de-blocking	O
formulas	O
were	O
employed	O
which	O
resulted	O
in	O
more	O
disk	O
blocks	O
per	O
logical	O
file	B-Operating_System
allocation	O
block	O
.	O
</s>
<s>
While	O
this	O
allowed	O
for	O
larger	O
file	B-Operating_System
sizes	O
,	O
it	O
also	O
meant	O
that	O
the	O
smallest	O
file	B-Operating_System
which	O
could	O
be	O
allocated	O
increased	O
in	O
size	O
from	O
1KB	O
(	O
on	O
single-density	O
drives	O
)	O
to	O
2KB	O
(	O
on	O
double-density	O
drives	O
)	O
and	O
so	O
on	O
,	O
up	O
to	O
32KB	O
for	O
a	O
file	B-Operating_System
containing	O
only	O
a	O
single	O
byte	O
.	O
</s>
<s>
File	B-Operating_System
modification	O
time	B-Operating_System
stamps	I-Operating_System
were	O
not	O
supported	O
in	O
releases	O
up	O
to	O
CP/M2.2	O
,	O
but	O
were	O
an	O
optional	O
feature	O
in	O
MP/M	B-Operating_System
and	O
CP/M3.0	O
.	O
</s>
<s>
CP/M2.2	O
had	O
no	O
subdirectories	O
in	O
the	O
file	B-Operating_System
structure	O
,	O
but	O
provided	O
16	O
numbered	O
user	O
areas	O
to	O
organize	O
files	O
on	O
a	O
disk	O
.	O
</s>
<s>
To	O
change	O
user	O
one	O
had	O
to	O
simply	O
type	B-Device
"	O
User	O
X	O
"	O
at	O
the	O
command	O
prompt	O
,	O
X	O
being	O
the	O
user	O
number	O
.	O
</s>
<s>
The	O
user	O
area	O
concept	O
was	O
to	O
make	O
the	O
single-user	O
version	O
of	O
CP/M	B-Application
somewhat	O
compatible	O
with	O
multi-user	O
MP/M	B-Operating_System
systems	O
.	O
</s>
<s>
A	O
common	O
patch	O
for	O
the	O
CP/M	B-Application
and	O
derivative	O
operating	B-General_Concept
systems	I-General_Concept
was	O
to	O
make	O
one	O
user	O
area	O
accessible	O
to	O
the	O
user	O
independent	O
of	O
the	O
currently	O
set	O
user	O
area	O
.	O
</s>
<s>
However	O
,	O
files	O
stored	O
in	O
the	O
USER	O
0	O
area	O
were	O
accessible	O
to	O
all	O
other	O
users	O
;	O
their	O
location	O
was	O
specified	O
with	O
a	O
prefatory	O
path	B-Application
,	O
since	O
the	O
files	O
of	O
USER	O
0	O
were	O
only	O
visible	O
to	O
someone	O
logged	O
in	O
as	O
USER	O
0	O
.	O
</s>
<s>
The	O
user	O
area	O
feature	O
arguably	O
had	O
little	O
utility	O
on	O
small	O
floppy	B-Device
disks	I-Device
,	O
but	O
it	O
was	O
useful	O
for	O
organizing	O
files	O
on	O
machines	O
with	O
hard	B-Device
drives	I-Device
.	O
</s>
<s>
For	O
example	O
,	O
a	O
secretary	O
could	O
do	O
data	B-General_Concept
entry	I-General_Concept
,	O
then	O
,	O
after	O
switching	O
USER	O
areas	O
,	O
another	O
employee	O
could	O
use	O
the	O
machine	O
to	O
do	O
billing	O
without	O
their	O
files	O
intermixing	O
.	O
</s>
<s>
Although	O
graphics-capable	O
S-100	O
systems	O
existed	O
from	O
the	O
commercialization	O
of	O
the	O
S-100	B-Architecture
bus	I-Architecture
,	O
CP/M	B-Application
did	O
not	O
provide	O
any	O
standardized	O
graphics	O
support	O
until	O
1982	O
with	O
GSX	B-Application
(	O
Graphics	B-Application
System	I-Application
Extension	I-Application
)	O
.	O
</s>
<s>
Owing	O
to	O
the	O
small	O
amount	O
of	O
available	O
memory	O
,	O
graphics	O
was	O
never	O
a	O
common	O
feature	O
associated	O
with	O
8-bit	O
CP/M	B-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
Most	O
systems	O
could	O
only	O
display	O
rudimentary	O
ASCII	B-Protocol
art	O
charts	O
and	O
diagrams	O
in	O
text	B-Application
mode	I-Application
or	O
by	O
using	O
a	O
custom	O
character	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
Some	O
computers	O
in	O
the	O
Kaypro	O
line	O
and	O
the	O
TRS-80	B-Device
Model	I-Device
4	I-Device
had	O
video	O
hardware	O
supporting	O
block	O
graphics	O
characters	O
,	O
and	O
these	O
were	O
accessible	O
to	O
assembler	B-Application
programmers	O
and	O
BASIC	O
programmers	O
using	O
the	O
CHR$	O
command	O
.	O
</s>
<s>
Some	O
companies	O
made	O
official	O
enhancements	O
of	O
CP/M	B-Application
based	O
on	O
Digital	O
Research	O
source	O
code	O
.	O
</s>
<s>
An	O
example	O
is	O
IMDOS	B-Operating_System
for	O
the	O
IMSAI	B-Device
8080	I-Device
computer	O
made	O
by	O
IMS	O
Associates	O
,	O
Inc.	O
,	O
a	O
clone	O
of	O
the	O
famous	O
Altair	B-Architecture
8800	I-Architecture
.	O
</s>
<s>
MSX-DOS	B-Operating_System
for	O
the	O
MSX	B-Operating_System
range	O
of	O
computers	O
is	O
CP/M	B-Application
-compatible	O
and	O
can	O
run	O
CP/M	B-Application
programs	O
.	O
</s>
<s>
The	O
Epson	B-Device
QX-10	I-Device
shipped	O
with	O
a	O
choice	O
of	O
CP/M	B-Application
or	O
the	O
compatible	O
TPM-II	O
or	O
TPM-III	O
.	O
</s>
<s>
The	O
British	O
ZX	B-Operating_System
Spectrum	I-Operating_System
compatible	O
SAM	B-Device
Coupé	I-Device
had	O
an	O
optional	O
CP/M	B-Application
-2.2	O
compatible	O
OS	O
called	O
.	O
</s>
<s>
The	O
Husky	B-Device
(	O
computer	O
)	O
ran	O
a	O
ROM-based	O
menu-driven	O
program	O
loader	O
called	O
DEMOS	O
which	O
could	O
run	O
many	O
CP/M	B-Application
applications	O
.	O
</s>
<s>
is	O
a	O
replacement	O
BDOS	O
for	O
CP/M	B-Application
-80	I-Application
2.2	O
written	O
by	O
Harold	O
F	O
.	O
Bower	O
and	O
Cameron	O
W	O
.	O
Cotrill	O
.	O
</s>
<s>
is	O
a	O
new	O
FOSS	O
CP/M	B-Application
2.2-compatible	O
operating	B-General_Concept
system	I-General_Concept
which	O
originally	O
contained	O
no	O
DR	O
code	O
.	O
</s>
<s>
Since	O
Bryan	O
Sparks	O
,	O
the	O
president	O
of	O
DR	O
owners	O
Lineo	O
,	O
granted	O
in	O
2022	O
to	O
modify	O
and	O
redistribute	O
CP/M	B-Application
code	O
,	O
developer	O
David	O
Given	O
is	O
updating	O
CPMish	O
with	O
some	O
parts	O
of	O
the	O
original	O
DR	O
CP/M	B-Application
.	O
</s>
<s>
Some	O
CP/M	B-Application
compatible	O
operating	B-General_Concept
systems	I-General_Concept
extended	O
the	O
basic	O
functionality	O
so	O
far	O
that	O
they	O
far	O
exceeded	O
the	O
original	O
,	O
for	O
example	O
the	O
multi-processor	B-Operating_System
capable	O
TurboDOS	B-Operating_System
.	O
</s>
<s>
A	O
number	O
of	O
CP/M	B-Application
-80	I-Application
derivatives	O
existed	O
in	O
the	O
former	O
Eastern	O
Bloc	O
under	O
various	O
names	O
,	O
including	O
SCP	O
(	O
)	O
,	O
SCP/M	O
,	O
CP/A	O
,	O
CP/J	O
,	O
CP/KC	O
,	O
CP/KSOB	O
,	O
CP/L	O
,	O
CP/Z	O
,	O
MICRODOS	O
,	O
BCU880	O
,	O
ZOAZ	O
,	O
OS/M	O
,	O
TOS/M	O
,	O
ZSDOS	O
,	O
M/OS	O
,	O
COS-PSA	O
,	O
DOS-PSA	O
,	O
CSOC	O
,	O
CSOS	O
,	O
CZ-CPM	B-Operating_System
and	O
others	O
.	O
</s>
<s>
There	O
were	O
also	O
CP/M	B-Operating_System
-86	I-Operating_System
derivatives	O
named	O
SCP1700	B-Operating_System
,	O
CP/K	B-Operating_System
and	O
K8918-OS	B-Operating_System
.	O
</s>
<s>
A	O
number	O
of	O
behaviors	O
exhibited	O
by	O
Microsoft	B-Application
Windows	I-Application
are	O
a	O
result	O
of	O
backward	B-General_Concept
compatibility	I-General_Concept
with	O
MS-DOS	B-Application
,	O
which	O
in	O
turn	O
attempted	O
some	O
backward	B-General_Concept
compatibility	I-General_Concept
with	O
CP/M	B-Application
.	O
</s>
<s>
The	O
drive	O
letter	O
and	O
8.3	O
filename	O
conventions	O
in	O
MS-DOS	B-Application
(	O
and	O
early	O
Windows	O
versions	O
)	O
were	O
originally	O
adopted	O
from	O
CP/M	B-Application
.	O
</s>
<s>
The	O
wildcard	B-Algorithm
matching	O
characters	O
used	O
by	O
Windows	O
(	O
?	O
</s>
<s>
and	O
*	O
)	O
are	O
based	O
on	O
those	O
of	O
CP/M	B-Application
,	O
as	O
are	O
the	O
reserved	O
filenames	O
used	O
to	O
redirect	B-Device
output	O
to	O
a	O
printer	O
(	O
"	O
PRN	B-Application
:	I-Application
"	O
)	O
,	O
and	O
the	O
console	B-Device
(	O
"	O
CON	B-Application
:	I-Application
"	O
)	O
.	O
</s>
<s>
The	O
drive	O
names	O
A	O
and	O
B	O
were	O
used	O
to	O
designate	O
the	O
two	O
floppy	B-Device
disk	I-Device
drives	I-Device
that	O
CP/M	B-Application
systems	O
typically	O
used	O
;	O
when	O
hard	B-Device
drives	I-Device
appeared	O
,	O
they	O
were	O
designated	O
C	B-Language
,	O
which	O
survived	O
into	O
MS-DOS	B-Application
as	O
the	O
C:\>	O
command	O
prompt	O
.	O
</s>
<s>
The	O
control	O
character	O
^Z	O
marking	O
the	O
end	B-Language
of	I-Language
some	I-Language
text	I-Language
files	I-Language
can	O
also	O
be	O
attributed	O
to	O
CP/M	B-Application
.	O
</s>
<s>
Various	O
commands	B-Application
in	O
DOS	B-Device
were	O
modelled	O
after	O
CP/M	B-Application
commands	B-Application
;	O
some	O
of	O
them	O
even	O
carried	O
the	O
same	O
name	O
,	O
like	O
DIR	B-Device
,	O
REN/RENAME	O
,	O
or	O
TYPE	B-Device
(	O
and	O
ERA/ERASE	O
in	O
DR-DOS	B-Application
)	O
.	O
</s>
<s>
File	B-Operating_System
extensions	O
like	O
.TXT	B-General_Concept
or	O
.COM	O
are	O
still	O
used	O
to	O
identify	O
file	B-Operating_System
types	O
on	O
many	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
1997	O
and	O
1998	O
,	O
Caldera	O
released	O
some	O
CP/M2.2	O
binaries	O
and	O
source	O
code	O
under	O
an	O
open	B-Application
source	I-Application
license	O
,	O
also	O
allowing	O
the	O
redistribution	O
and	O
modification	O
of	O
further	O
collected	O
Digital	O
Research	O
files	O
related	O
to	O
the	O
CP/M	B-Application
and	O
MP/M	B-Operating_System
families	O
through	O
Tim	O
Olmstead	O
's	O
"	O
The	O
Unofficial	O
CP/M	B-Application
Web	O
site	O
"	O
since	O
1997	O
.	O
</s>
<s>
In	O
October	O
2014	O
,	O
to	O
mark	O
the	O
40th	O
anniversary	O
of	O
the	O
first	O
presentation	O
of	O
CP/M	B-Application
,	O
the	O
Computer	O
History	O
Museum	O
released	O
early	O
source	O
code	O
versions	O
of	O
CP/M	B-Application
.	O
</s>
<s>
,	O
there	O
are	O
a	O
number	O
of	O
active	O
vintage	O
,	O
hobby	O
and	O
retro-computer	O
people	O
and	O
groups	O
,	O
and	O
some	O
small	O
commercial	O
businesses	O
,	O
still	O
developing	O
and	O
supporting	O
computer	B-Device
platforms	I-Device
that	O
use	O
CP/M	B-Application
(	O
mostly	O
2.2	O
)	O
as	O
the	O
host	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
