<s>
A	O
microassembler	B-Application
is	O
a	O
computer	B-Application
program	I-Application
that	O
helps	O
prepare	O
a	O
microprogram	B-Device
,	O
called	O
firmware	O
,	O
to	O
control	O
the	O
low	O
level	O
operation	O
of	O
a	O
computer	O
in	O
much	O
the	O
same	O
way	O
an	O
assembler	O
helps	O
prepare	O
higher	O
level	O
code	O
for	O
a	O
processor	B-General_Concept
.	O
</s>
<s>
The	O
difference	O
is	O
that	O
the	O
microprogram	B-Device
is	O
usually	O
only	O
developed	O
by	O
the	O
processor	B-General_Concept
manufacturer	O
and	O
works	O
intimately	O
with	O
the	O
computer	B-Architecture
hardware	I-Architecture
.	O
</s>
<s>
On	O
a	O
microprogrammed	O
computer	O
the	O
microprogram	B-Device
implements	O
the	O
operations	O
of	O
the	O
instruction	B-General_Concept
set	I-General_Concept
in	O
which	O
any	O
normal	O
program	O
(	O
including	O
both	O
application	B-Application
programs	I-Application
and	O
operating	B-General_Concept
systems	I-General_Concept
)	O
is	O
written	O
.	O
</s>
<s>
The	O
use	O
of	O
a	O
microprogram	B-Device
allows	O
the	O
manufacturer	O
to	O
fix	O
certain	O
mistakes	O
,	O
including	O
working	O
around	O
hardware	B-Architecture
design	O
errors	O
,	O
without	O
modifying	O
the	O
hardware	B-Architecture
.	O
</s>
<s>
Another	O
means	O
of	O
employing	O
microassembler-generated	O
microprograms	B-Device
is	O
in	O
allowing	O
the	O
same	O
hardware	B-Architecture
to	O
run	O
different	O
instruction	B-General_Concept
sets	I-General_Concept
.	O
</s>
<s>
After	O
it	O
is	O
assembled	O
,	O
the	O
microprogram	B-Device
is	O
then	O
loaded	O
to	O
a	O
control	B-General_Concept
store	I-General_Concept
to	O
become	O
part	O
of	O
the	O
logic	O
of	O
a	O
CPU	B-General_Concept
's	O
control	B-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
Some	O
microassemblers	B-Application
are	O
more	O
generalized	O
and	O
are	O
not	O
targeted	O
at	O
a	O
single	O
computer	O
architecture	O
.	O
</s>
<s>
For	O
example	O
,	O
through	O
the	O
use	O
of	O
macro-assembler-like	O
capabilities	O
,	O
Digital	O
Equipment	O
Corporation	O
used	O
their	O
MICRO2	O
microassembler	B-Application
for	O
a	O
very	O
wide	O
range	O
of	O
computer	O
architectures	O
and	O
implementations	O
.	O
</s>
<s>
If	O
a	O
given	O
computer	O
implementation	O
supports	O
a	O
writeable	B-General_Concept
control	I-General_Concept
store	I-General_Concept
,	O
the	O
microassembler	B-Application
is	O
usually	O
provided	O
to	O
customers	O
as	O
a	O
means	O
of	O
writing	O
customized	O
microcode	B-Device
.	O
</s>
<s>
In	O
the	O
process	O
of	O
microcode	B-Device
assembly	O
it	O
is	O
helpful	O
to	O
verify	O
the	O
microprogram	B-Device
with	O
emulation	O
tools	O
before	O
distribution	O
.	O
</s>
<s>
Nowadays	O
,	O
microcoding	B-Device
has	O
experienced	O
a	O
revival	O
,	O
since	O
it	O
is	O
possible	O
to	O
correct	O
and	O
optimize	O
the	O
firmware	O
of	O
processing	O
units	O
already	O
manufactured	O
or	O
sold	O
,	O
in	O
order	O
to	O
adapt	O
to	O
specific	O
operating	B-General_Concept
systems	I-General_Concept
or	O
to	O
fix	O
hardware	B-Architecture
bugs	O
.	O
</s>
<s>
However	O
,	O
a	O
commonly	O
usable	O
microassembler	B-Application
for	O
today	O
's	O
CPUs	O
is	O
not	O
available	O
to	O
manipulate	O
the	O
microcode	B-Device
.	O
</s>
<s>
Unfortunately	O
,	O
knowledge	O
of	O
a	O
processor	B-General_Concept
's	O
microcode	B-Device
is	O
usually	O
considered	O
proprietary	O
information	O
so	O
it	O
is	O
difficult	O
to	O
obtain	O
information	O
about	O
how	O
to	O
modify	O
it	O
.	O
</s>
