<s>
The	O
Extended	B-Device
Industry	I-Device
Standard	I-Device
Architecture	I-Device
(	O
in	O
practice	O
almost	O
always	O
shortened	O
to	O
EISA	O
and	O
frequently	O
pronounced	O
"	O
eee-suh	O
"	O
)	O
is	O
a	O
bus	O
standard	O
for	O
IBM	B-Device
PC	I-Device
compatible	O
computers	O
.	O
</s>
<s>
It	O
was	O
announced	O
in	O
September	O
1988	O
by	O
a	O
consortium	B-Application
of	O
PC	O
clone	O
vendors	O
(	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
)	O
as	O
an	O
alternative	O
to	O
IBM	O
's	O
proprietary	B-Device
Micro	B-Device
Channel	I-Device
architecture	I-Device
(	O
MCA	B-Device
)	O
in	O
its	O
PS/2	B-Device
series	O
.	O
</s>
<s>
In	O
comparison	O
with	O
the	O
AT	B-Architecture
bus	I-Architecture
,	O
which	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
retroactively	O
renamed	O
to	O
the	O
ISA	B-Architecture
bus	I-Architecture
to	O
avoid	O
infringing	O
IBM	O
's	O
trademark	O
on	O
its	O
PC/AT	B-Operating_System
computer	I-Operating_System
,	O
EISA	O
is	O
extended	O
to	O
32	O
bits	O
and	O
allows	O
more	O
than	O
one	O
CPU	B-General_Concept
to	O
share	O
the	O
bus	O
.	O
</s>
<s>
The	O
bus	B-Architecture
mastering	I-Architecture
support	O
is	O
also	O
enhanced	O
to	O
provide	O
access	O
to	O
4GB	O
of	O
memory	O
.	O
</s>
<s>
Unlike	O
MCA	B-Device
,	O
EISA	O
can	O
accept	O
older	O
XT	B-Architecture
and	O
ISA	B-Architecture
boards	O
the	O
lines	O
and	O
slots	O
for	O
EISA	O
are	O
a	O
superset	O
of	O
ISA	B-Architecture
.	O
</s>
<s>
EISA	O
was	O
much	O
favoured	O
by	O
manufacturers	O
due	O
to	O
the	O
proprietary	B-Device
nature	O
of	O
MCA	B-Device
,	O
and	O
even	O
IBM	O
produced	O
some	O
machines	O
supporting	O
it	O
.	O
</s>
<s>
It	O
was	O
somewhat	O
expensive	O
to	O
implement	O
(	O
though	O
not	O
as	O
much	O
as	O
MCA	B-Device
)	O
,	O
so	O
it	O
never	O
became	O
particularly	O
popular	O
in	O
desktop	O
PCs	O
.	O
</s>
<s>
However	O
,	O
it	O
was	O
reasonably	O
successful	O
in	O
the	O
server	B-Application
market	O
,	O
as	O
it	O
was	O
better	O
suited	O
to	O
bandwidth-intensive	O
tasks	O
(	O
such	O
as	O
disk	O
access	O
and	O
networking	O
)	O
.	O
</s>
<s>
Most	O
EISA	O
cards	O
produced	O
were	O
either	O
SCSI	B-Architecture
or	O
network	O
cards	O
.	O
</s>
<s>
EISA	O
was	O
also	O
available	O
on	O
some	O
non-IBM-compatible	O
machines	O
such	O
as	O
the	O
DEC	B-Device
AlphaServer	I-Device
,	O
HP	O
9000	O
D-class	O
,	O
SGI	B-Application
Indigo2	I-Application
and	O
MIPS	B-Device
Magnum	I-Device
.	O
</s>
<s>
By	O
the	O
time	O
there	O
was	O
a	O
strong	O
market	O
need	O
for	O
a	O
bus	O
of	O
these	O
speeds	O
and	O
capabilities	O
for	O
desktop	O
computers	O
,	O
the	O
VESA	O
Local	O
Bus	O
and	O
later	O
PCI	B-Protocol
filled	O
this	O
niche	O
,	O
and	O
EISA	O
vanished	O
into	O
obscurity	O
.	O
</s>
<s>
The	O
original	O
IBM	B-Device
PC	I-Device
included	O
five	O
8-bit	O
slots	O
,	O
running	O
at	O
the	O
system	O
clock	O
speed	O
of	O
4.77MHz	O
.	O
</s>
<s>
The	O
PC/AT	B-Operating_System
,	O
introduced	O
in	O
1984	O
,	O
had	O
three	O
8-bit	O
slots	O
and	O
five	O
16-bit	O
slots	O
,	O
all	O
running	O
at	O
the	O
system	O
clock	O
speed	O
of	O
6MHz	O
in	O
the	O
earlier	O
models	O
and	O
8MHz	O
in	O
the	O
last	O
version	O
of	O
the	O
computer	O
.	O
</s>
<s>
One	O
of	O
the	O
key	O
reasons	O
for	O
the	O
success	O
of	O
the	O
IBM	B-Device
PC	I-Device
(	O
and	O
the	O
PC	O
clones	O
that	O
followed	O
it	O
)	O
was	O
the	O
active	O
ecosystem	O
of	O
third-party	O
expansion	O
cards	O
available	O
for	O
the	O
machines	O
.	O
</s>
<s>
Unfortunately	O
,	O
because	O
the	O
ISA	B-Architecture
bus	I-Architecture
was	O
originally	O
locked	O
to	O
the	O
processor	O
clock	O
,	O
this	O
meant	O
that	O
some	O
286	O
machines	O
had	O
ISA	B-Architecture
buses	O
that	O
ran	O
at	O
10	O
,	O
12	O
,	O
or	O
even	O
16MHz	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	O
first	O
systems	O
to	O
clock	O
the	O
ISA	B-Architecture
bus	I-Architecture
at	O
8MHz	O
were	O
the	O
turbo	O
Intel	B-Device
8088	I-Device
clones	O
that	O
clocked	O
the	O
processors	O
at	O
8MHz	O
.	O
</s>
<s>
As	O
companies	O
like	O
Dell	O
modified	O
the	O
AT	B-Architecture
bus	I-Architecture
design	O
,	O
the	O
architecture	O
was	O
so	O
well	O
entrenched	O
that	O
no	O
single	O
clone	O
manufacturer	O
had	O
the	O
leverage	O
to	O
create	O
a	O
standardized	O
alternative	O
,	O
and	O
there	O
was	O
no	O
compelling	O
reason	O
for	O
them	O
to	O
cooperate	O
on	O
a	O
new	O
standard	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
when	O
the	O
first	O
386-based	O
system	O
(	O
the	O
Compaq	B-Device
Deskpro	I-Device
386	I-Device
)	O
hit	O
the	O
market	O
in	O
1986	O
,	O
it	O
still	O
supported	O
16-bit	O
slots	O
.	O
</s>
<s>
Other	O
386	B-General_Concept
PCs	O
followed	O
suit	O
,	O
and	O
the	O
AT	O
(	O
later	O
ISA	B-Architecture
)	O
bus	O
remained	O
a	O
part	O
of	O
most	O
systems	O
even	O
into	O
the	O
late	O
1990s	O
.	O
</s>
<s>
In	O
1987	O
,	O
IBM	O
released	O
the	O
PS/2	B-Device
line	O
of	O
computers	O
,	O
which	O
included	O
the	O
MCA	B-Device
bus	I-Device
.	O
</s>
<s>
MCA	B-Device
included	O
numerous	O
enhancements	O
over	O
the	O
16-bit	O
AT	B-Architecture
bus	I-Architecture
,	O
including	O
bus	B-Architecture
mastering	I-Architecture
,	O
burst	B-Architecture
mode	I-Architecture
,	O
software-configurable	O
resources	O
,	O
and	O
32-bit	O
capabilities	O
.	O
</s>
<s>
A	O
few	O
manufacturers	O
did	O
produce	O
licensed	O
MCA	B-Device
machines	O
(	O
most	O
notably	O
,	O
NCR	O
)	O
,	O
but	O
overall	O
the	O
industry	O
balked	O
at	O
IBM	O
's	O
restrictions	O
.	O
</s>
<s>
Steve	O
Gibson	O
proposed	O
that	O
clone	O
makers	O
adopt	O
NuBus	B-Device
.	O
</s>
<s>
A	O
group	O
of	O
companies	O
led	O
by	O
Compaq	O
(	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
)	O
created	O
a	O
new	O
bus	O
instead	O
.	O
</s>
<s>
This	O
new	O
bus	O
was	O
named	O
the	O
Extended	O
(	O
or	O
Enhanced	O
)	O
Industry	B-Architecture
Standard	I-Architecture
Architecture	I-Architecture
,	O
or	O
"	O
EISA	O
"	O
,	O
while	O
the	O
older	O
AT	B-Architecture
bus	I-Architecture
had	O
already	O
been	O
renamed	O
Industry	B-Architecture
Standard	I-Architecture
Architecture	I-Architecture
,	O
or	O
"	O
ISA	B-Architecture
"	O
.	O
</s>
<s>
This	O
provided	O
virtually	O
all	O
of	O
the	O
technical	O
advantages	O
of	O
MCA	B-Device
,	O
while	O
remaining	O
compatible	O
with	O
existing	O
8-bit	O
and	O
16-bit	O
cards	O
,	O
and	O
(	O
most	O
enticing	O
to	O
system	O
and	O
card	O
makers	O
)	O
minimal	O
licensing	O
cost	O
.	O
</s>
<s>
The	O
EISA	B-Device
bus	I-Device
slot	O
is	O
a	O
two-level	O
staggered	O
pin	O
system	O
,	O
with	O
the	O
upper	O
part	O
of	O
the	O
slot	O
corresponding	O
to	O
the	O
standard	O
ISA	B-Architecture
bus	I-Architecture
pin	O
layout	O
.	O
</s>
<s>
The	O
additional	O
features	O
of	O
the	O
EISA	B-Device
bus	I-Device
are	O
implemented	O
on	O
the	O
lower	O
part	O
of	O
the	O
slot	O
connector	O
,	O
using	O
thin	O
traces	O
inserted	O
into	O
the	O
insulating	O
gap	O
of	O
the	O
upper	O
/	O
ISA	B-Architecture
card	I-Architecture
card	O
edge	O
connector	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
lower	O
part	O
of	O
the	O
bus	O
has	O
five	O
keying	O
notches	O
,	O
so	O
an	O
ISA	B-Architecture
card	I-Architecture
with	O
unusually	O
long	O
traces	O
cannot	O
accidentally	O
extend	O
down	O
into	O
the	O
lower	O
part	O
of	O
the	O
slot	O
.	O
</s>
<s>
Intel	O
introduced	O
their	O
first	O
EISA	O
chipset	B-Device
(	O
and	O
also	O
their	O
first	O
chipset	B-Device
in	O
the	O
modern	O
sense	O
of	O
the	O
word	O
)	O
as	O
the	O
82350	O
in	O
September	O
1989	O
.	O
</s>
<s>
The	O
first	O
EISA	O
computer	O
announced	O
was	O
the	O
HP	B-Device
Vectra	I-Device
486	O
in	O
October	O
1989	O
.	O
</s>
<s>
The	O
first	O
EISA	O
computers	O
to	O
hit	O
the	O
market	O
were	O
the	O
Compaq	B-Device
Deskpro	I-Device
486	O
and	O
the	O
SystemPro	B-Application
.	O
</s>
<s>
The	O
SystemPro	B-Application
,	O
being	O
one	O
of	O
the	O
first	O
PC-style	O
systems	O
designed	O
as	O
a	O
network	B-Application
server	I-Application
,	O
was	O
built	O
from	O
the	O
ground	O
up	O
to	O
take	O
full	O
advantage	O
of	O
the	O
EISA	B-Device
bus	I-Device
.	O
</s>
<s>
It	O
included	O
such	O
features	O
as	O
multiprocessing	B-Operating_System
,	O
hardware	O
RAID	B-Architecture
,	O
and	O
bus-mastering	O
network	O
cards	O
.	O
</s>
<s>
One	O
of	O
the	O
benefits	O
to	O
come	O
out	O
of	O
the	O
EISA	O
standard	O
was	O
a	O
final	O
codification	O
of	O
the	O
standard	O
to	O
which	O
ISA	B-Architecture
slots	I-Architecture
and	O
cards	O
should	O
be	O
held	O
(	O
in	O
particular	O
,	O
clock	O
speed	O
was	O
fixed	O
at	O
an	O
industry	O
standard	O
of	O
8.33MHz	O
)	O
.	O
</s>
<s>
Thus	O
,	O
even	O
systems	O
that	O
did	O
n't	O
use	O
the	O
EISA	B-Device
bus	I-Device
gained	O
the	O
advantage	O
of	O
having	O
the	O
ISA	B-Architecture
standardized	O
,	O
which	O
contributed	O
to	O
its	O
longevity	O
.	O
</s>
<s>
The	O
Gang	B-Device
of	I-Device
Nine	I-Device
was	O
the	O
informal	O
name	O
given	O
to	O
the	O
consortium	B-Application
of	O
personal	O
computer	O
manufacturing	O
companies	O
,	O
led	O
by	O
Compaq	O
,	O
that	O
together	O
created	O
the	O
EISA	B-Device
bus	I-Device
.	O
</s>
<s>
Compaq	O
was	O
among	O
the	O
first	O
clone	O
makers	O
,	O
and	O
had	O
the	O
largest	O
market	O
share	O
for	O
386-based	O
computers	O
.	O
</s>
<s>
Rival	O
members	O
generally	O
acknowledged	O
its	O
leadership	O
,	O
with	O
one	O
stating	O
in	O
1989	O
that	O
within	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
"	O
when	O
you	O
have	O
10	O
people	O
sit	O
down	O
before	O
a	O
table	O
to	O
write	O
a	O
letter	O
to	O
the	O
president	O
,	O
someone	O
has	O
to	O
write	O
the	O
letter	O
.	O
</s>
<s>
Although	O
the	O
MCA	B-Device
bus	I-Device
had	O
a	O
slight	O
performance	O
advantage	O
over	O
EISA	O
(	O
bus	O
speed	O
of	O
10MHz	O
,	O
compared	O
to	O
8.33MHz	O
)	O
,	O
EISA	O
contained	O
almost	O
all	O
of	O
the	O
technological	O
benefits	O
that	O
MCA	B-Device
boasted	O
,	O
including	O
bus	B-Architecture
mastering	I-Architecture
,	O
burst	B-Architecture
mode	I-Architecture
,	O
software-configurable	O
resources	O
,	O
and	O
32-bit	O
data/address	O
buses	O
.	O
</s>
<s>
These	O
brought	O
EISA	O
nearly	O
to	O
par	O
with	O
MCA	B-Device
from	O
a	O
performance	O
standpoint	O
,	O
and	O
EISA	O
easily	O
defeated	O
MCA	B-Device
in	O
industry	O
support	O
.	O
</s>
<s>
EISA	O
replaced	O
the	O
tedious	O
jumper	B-Device
configuration	O
common	O
with	O
ISA	B-Architecture
cards	I-Architecture
with	O
software-based	O
configuration	O
.	O
</s>
<s>
Every	O
EISA	O
system	O
shipped	O
with	O
an	O
EISA	O
configuration	O
utility	O
;	O
this	O
was	O
usually	O
a	O
slightly	O
customized	O
version	O
of	O
the	O
standard	O
utilities	O
written	O
by	O
the	O
EISA	O
chipset	B-Device
makers	O
.	O
</s>
<s>
The	O
user	O
would	O
boot	O
into	O
this	O
utility	O
,	O
either	O
from	O
floppy	B-Device
disk	I-Device
or	O
on	O
a	O
dedicated	O
hard-drive	O
partition	O
.	O
</s>
<s>
on	O
any	O
EISA	O
card	O
(	O
each	O
EISA	O
card	O
would	O
include	O
a	O
disk	O
with	O
information	O
that	O
described	O
the	O
available	O
options	O
on	O
the	O
card	O
)	O
or	O
on	O
the	O
EISA	O
system	O
motherboard	B-Device
.	O
</s>
<s>
The	O
user	O
could	O
also	O
enter	O
information	O
about	O
ISA	B-Architecture
cards	I-Architecture
in	O
the	O
system	O
,	O
allowing	O
the	O
utility	O
to	O
automatically	O
reconfigure	O
EISA	O
cards	O
to	O
avoid	O
resource	O
conflicts	O
.	O
</s>
<s>
Similarly	O
,	O
Windows	B-Application
95	I-Application
,	O
with	O
its	O
Plug-and-Play	B-Device
capability	O
,	O
was	O
not	O
able	O
to	O
change	O
the	O
configuration	O
of	O
EISA	O
cards	O
,	O
but	O
it	O
could	O
detect	O
the	O
cards	O
,	O
read	O
their	O
configuration	O
,	O
and	O
reconfigure	O
Plug-and-Play	B-Device
hardware	O
to	O
avoid	O
resource	O
conflicts	O
.	O
</s>
<s>
Windows	B-Application
95	I-Application
would	O
also	O
automatically	O
attempt	O
to	O
install	O
appropriate	O
drivers	O
for	O
detected	O
EISA	O
cards	O
.	O
</s>
<s>
Dell	O
was	O
a	O
notable	O
clome	O
maker	O
that	O
did	O
not	O
join	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
.	O
</s>
<s>
Many	O
manufacturers	O
,	O
including	O
those	O
in	O
the	O
Gang	B-Device
of	I-Device
Nine	I-Device
,	O
researched	O
the	O
possibility	O
of	O
using	O
MCA	B-Device
.	O
</s>
<s>
For	O
example	O
,	O
Compaq	O
actually	O
produced	O
prototype	O
DeskPro	B-Device
systems	O
using	O
the	O
bus	O
.	O
</s>
<s>
However	O
,	O
these	O
were	O
never	O
put	O
into	O
production	O
,	O
and	O
when	O
it	O
was	O
clear	O
that	O
MCA	B-Device
had	O
lost	O
,	O
Compaq	O
allowed	O
its	O
MCA	B-Device
license	O
to	O
expire	O
(	O
the	O
license	O
actually	O
cost	O
relatively	O
little	O
;	O
the	O
primary	O
costs	O
associated	O
with	O
MCA	B-Device
,	O
and	O
at	O
which	O
the	O
industry	O
revolted	O
,	O
were	O
royalties	O
to	O
be	O
paid	O
per	O
system	O
shipped	O
)	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
when	O
it	O
became	O
clear	O
to	O
IBM	O
that	O
Micro	B-Device
Channel	I-Device
was	O
dying	O
,	O
IBM	O
actually	O
licensed	O
EISA	O
for	O
use	O
in	O
a	O
few	O
server	B-Application
systems	O
.	O
</s>
<s>
As	O
a	O
final	O
jab	O
at	O
their	O
competitor	O
,	O
Compaq	O
(	O
leader	O
of	O
the	O
EISA	O
consortium	B-Application
)	O
did	O
n't	O
cash	O
the	O
first	O
check	O
sent	O
by	O
IBM	O
for	O
the	O
EISA	O
license	O
.	O
</s>
