<s>
The	O
Amiga	O
2000	O
,	O
or	O
A2000	O
,	O
is	O
a	O
personal	B-Device
computer	I-Device
released	O
by	O
Commodore	O
in	O
March	O
1987	O
.	O
</s>
<s>
It	O
was	O
introduced	O
as	O
a	O
"	O
big	O
box	O
"	O
expandable	O
variant	O
of	O
the	O
Amiga	B-Device
1000	I-Device
but	O
quickly	O
redesigned	O
to	O
share	O
most	O
of	O
its	O
electronic	O
components	O
with	O
the	O
contemporary	O
Amiga	B-Device
500	I-Device
for	O
cost	O
reduction	O
.	O
</s>
<s>
Expansion	O
capabilities	O
include	O
two	O
3.5	B-Device
"	I-Device
drive	B-Device
bays	I-Device
(	O
one	O
of	O
which	O
is	O
used	O
by	O
the	O
included	O
floppy	B-Device
drive	I-Device
)	O
and	O
one	O
5.25	B-Device
"	I-Device
bay	O
that	O
could	O
be	O
used	O
by	O
a	O
5.25	B-Device
"	I-Device
floppy	B-Device
drive	I-Device
(	O
for	O
IBM	B-Device
PC	I-Device
compatibility	O
)	O
,	O
a	O
hard	B-Device
drive	I-Device
,	O
or	O
CD-ROM	B-Device
once	O
they	O
became	O
available	O
.	O
</s>
<s>
SCSI	B-Architecture
host	O
adapters	O
,	O
memory	B-Device
cards	I-Device
,	O
CPU	B-General_Concept
cards	I-General_Concept
,	O
network	B-Protocol
cards	I-Protocol
,	O
graphics	B-Device
cards	I-Device
,	O
serial	B-Protocol
port	I-Protocol
cards	O
,	O
and	O
PC	O
compatibility	O
cards	O
were	O
available	O
,	O
and	O
multiple	O
expansions	O
can	O
be	O
used	O
simultaneously	O
without	O
requiring	O
an	O
expansion	O
cage	O
like	O
the	O
Amiga	B-Device
1000	I-Device
does	O
.	O
</s>
<s>
Not	O
only	O
does	O
the	O
Amiga	O
2000	O
include	O
five	O
Zorro	B-Device
II	I-Device
card	O
slots	O
,	O
the	O
motherboard	O
also	O
has	O
four	O
PC	B-Architecture
ISA	I-Architecture
slots	O
,	O
two	O
of	O
which	O
are	O
inline	O
with	O
Zorro	B-Device
II	I-Device
slots	O
for	O
use	O
with	O
the	O
A2088	O
bridgeboard	O
,	O
which	O
adds	O
IBM	B-Device
PC	I-Device
XT	I-Device
compatibility	O
to	O
the	O
A2000	O
.	O
</s>
<s>
The	O
Amiga	O
2000	O
was	O
the	O
most	O
versatile	O
and	O
expandable	O
Amiga	O
computer	O
until	O
the	O
Amiga	B-Device
3000	I-Device
was	O
introduced	O
three	O
years	O
later	O
.	O
</s>
<s>
Aimed	O
at	O
the	O
high-end	O
market	O
,	O
the	O
original	O
Europe-only	O
model	O
adds	O
a	O
Zorro	B-Device
II	I-Device
backplane	O
,	O
implemented	O
in	O
programmable	O
logic	O
,	O
to	O
the	O
custom	O
Amiga	O
chipset	O
used	O
in	O
the	O
Amiga	B-Device
1000	I-Device
.	O
</s>
<s>
Later	O
improved	O
models	O
have	O
redesigned	O
hardware	O
using	O
the	O
more	O
highly	O
integrated	O
A500	B-Device
chipset	O
,	O
with	O
the	O
addition	O
of	O
a	O
gate-array	O
called	O
"	O
Buster	O
"	O
,	O
which	O
integrates	O
the	O
Zorro	O
subsystem	O
.	O
</s>
<s>
Like	O
the	O
earlier	O
model	O
,	O
the	O
Amiga	B-Device
1000	I-Device
,	O
and	O
most	O
IBM	B-Device
PC	I-Device
compatibles	O
of	O
the	O
era	O
,	O
but	O
unlike	O
the	O
Amiga	B-Device
500	I-Device
,	O
the	O
A2000	O
comes	O
in	O
a	O
desktop	B-General_Concept
case	I-General_Concept
with	O
a	O
separate	O
keyboard	O
.	O
</s>
<s>
The	O
case	O
is	O
taller	O
than	O
the	O
A1000	O
to	O
accommodate	O
expansion	O
cards	O
,	O
two	O
3.5	B-Device
"	I-Device
and	O
one	O
5.25	B-Device
"	I-Device
drive	B-Device
bays	I-Device
.	O
</s>
<s>
The	O
A2000	O
's	O
case	O
lacks	O
the	O
"	O
keyboard	O
garage	O
"	O
of	O
the	O
Amiga	B-Device
1000	I-Device
but	O
has	O
space	O
for	O
five	O
Zorro	B-Device
II	I-Device
expansion	O
slots	O
,	O
two	O
16-bit	O
and	O
two	O
8-bit	O
ISA	B-Architecture
slots	I-Architecture
,	O
a	O
CPU	B-General_Concept
upgrade	O
slot	O
and	O
a	O
video	O
slot	O
.	O
</s>
<s>
The	O
Amiga	O
2000	O
offers	O
graphics	O
capabilities	O
exceeded	O
among	O
its	O
contemporaries	O
only	O
by	O
the	O
Macintosh	B-Device
II	I-Device
,	O
which	O
sold	O
for	O
about	O
twice	O
the	O
price	O
of	O
a	O
comparably-outfitted	O
Amiga	O
2000	O
additionally	O
equipped	O
with	O
the	O
IBM	B-Device
PC	I-Device
Compatible	O
bridgeboard	O
and	O
5.25	B-Device
"	I-Device
floppy	B-Device
disk	I-Device
drive	I-Device
(	O
which	O
was	O
important	O
for	O
real-world	O
interoperability	O
at	O
this	O
time	O
)	O
.	O
</s>
<s>
The	O
Amiga	O
2000	O
was	O
designed	O
with	O
an	O
open	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
The	O
final	O
design	O
was	O
the	O
result	O
of	O
an	O
internal	O
battle	O
within	O
Commodore	O
,	O
which	O
pitted	O
the	O
USA	O
division	O
,	O
who	O
wanted	O
to	O
build	O
a	O
system	O
more	O
like	O
the	O
Amiga	B-Device
3000	I-Device
(	O
and	O
1000	O
)	O
,	O
against	O
the	O
German	O
division	O
,	O
which	O
was	O
fresh	O
from	O
the	O
successful	O
introduction	O
of	O
the	O
first	O
Commodore	B-Device
PC-compatible	I-Device
systems	I-Device
and	O
planned	O
to	O
include	O
this	O
capability	O
in	O
the	O
Amiga	O
2000	O
from	O
the	O
start	O
.	O
</s>
<s>
The	O
bottom-line	O
practicality	O
of	O
the	O
German	O
design	O
won	O
out	O
,	O
and	O
the	O
final	O
A2000	O
shipped	O
with	O
not	O
only	O
Zorro	B-Device
II	I-Device
slots	O
,	O
but	O
a	O
complement	O
of	O
PC	O
standard	O
(	O
for	O
the	O
day	O
)	O
ISA	B-Architecture
slots	I-Architecture
.	O
</s>
<s>
The	O
original	O
motherboard	O
was	O
based	O
on	O
the	O
previous	O
Amiga	B-Device
1000	I-Device
with	O
the	O
addition	O
of	O
expansion	O
slots	O
,	O
and	O
so	O
suffered	O
all	O
the	O
same	O
limitations	O
.	O
</s>
<s>
This	O
was	O
soon	O
replaced	O
by	O
the	O
"	O
B2000-CR	O
"	O
version	O
designed	O
by	O
Dave	O
Haynie	O
and	O
Terry	O
Fisher	O
(	O
whose	O
names	O
are	O
printed	O
on	O
the	O
board	O
)	O
,	O
which	O
was	O
instead	O
based	O
on	O
the	O
Amiga	B-Device
500	I-Device
's	O
improved	O
design	O
.	O
</s>
<s>
The	O
practical	O
differences	O
are	O
that	O
the	O
early	O
2000	O
motherboard	O
only	O
has	O
512	O
kilobytes	O
of	O
ram	B-Architecture
installed	O
,	O
cannot	O
be	O
upgraded	O
with	O
newer	O
versions	O
of	O
the	O
chipset	O
,	O
requires	O
the	O
original	O
processor	B-General_Concept
to	O
be	O
removed	O
when	O
installing	O
a	O
processor	B-General_Concept
card	O
,	O
and	O
cannot	O
use	O
a	O
video	O
slot	O
mounted	O
flickerfixer	O
.	O
</s>
<s>
The	O
original	O
Amiga	O
2000	O
shipped	O
with	O
just	O
a	O
single	O
floppy	B-Device
drive	I-Device
for	O
storage	B-General_Concept
.	O
</s>
<s>
This	O
was	O
followed	O
up	O
fairly	O
early	O
by	O
the	O
Amiga	O
2000/HD	O
,	O
which	O
bundled	O
an	O
Amiga	O
2090	O
hard	B-Device
drive	I-Device
controller	O
and	O
a	O
SCSI-based	O
hard	B-Device
drive	I-Device
.	O
</s>
<s>
In	O
1988	O
,	O
Commodore	O
shipped	O
the	O
Amiga	O
2500/20	O
,	O
which	O
added	O
the	O
Amiga	O
2620	O
CPU	B-General_Concept
card	I-General_Concept
to	O
the	O
CPU	B-General_Concept
slot	O
,	O
a	O
14.3MHz	O
68020	B-Device
,	O
a	O
68881	B-General_Concept
FPU	B-General_Concept
,	O
and	O
a	O
68851	B-General_Concept
MMU	B-General_Concept
to	O
the	O
A2000	O
,	O
along	O
with	O
2MB	O
of	O
32-bit-wide	O
memory	O
.	O
</s>
<s>
The	O
A2000	O
's	O
original	O
68000	B-Device
CPU	B-General_Concept
remained	O
installed	O
on	O
the	O
motherboard	O
of	O
these	O
machines	O
,	O
but	O
is	O
not	O
used	O
.	O
</s>
<s>
In	O
1989	O
this	O
model	O
was	O
replaced	O
by	O
the	O
Amiga	O
2500/30	O
,	O
which	O
added	O
an	O
Amiga	O
2630	O
CPU	B-General_Concept
card	I-General_Concept
:	O
25MHz	O
68030	B-Device
and	O
the	O
68882	B-General_Concept
FPU	B-General_Concept
with	O
up	O
to	O
4MB	O
of	O
32-bit	O
memory	O
.	O
</s>
<s>
The	O
A1500	O
shipped	O
with	O
dual	O
floppy	B-Device
drives	I-Device
,	O
and	O
1MB	O
of	O
ChipRAM	O
as	O
standard	O
.	O
</s>
<s>
Initial	O
units	O
came	O
with	O
Kickstart	B-Device
1.3	O
(	O
and	O
thus	O
AmigaOS	B-Application
1.3	O
)	O
,	O
though	O
the	O
Original	B-Device
Chipset	I-Device
onboard	O
includes	O
a	O
later	O
Agnus	B-Device
revision	O
allowing	O
the	O
1MB	O
of	O
ChipRAM	O
.	O
</s>
<s>
Later	O
machines	O
came	O
with	O
the	O
ECS	B-Device
chipset	O
and	O
AmigaOS	B-Application
2.04	O
.	O
</s>
<s>
The	O
second	O
floppy	B-Device
drive	I-Device
replaces	O
the	O
hard	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
The	O
A1500	O
has	O
no	O
hard	B-Device
disk	I-Device
drive	I-Device
as	O
standard	O
.	O
</s>
<s>
As	O
the	O
only	O
significant	O
difference	O
A1500s	O
could	O
be	O
upgraded	O
into	O
A2000/HDs	O
by	O
addition	O
of	O
a	O
hard	B-Device
disk	I-Device
controller	O
(	O
and	O
associated	O
drive	O
)	O
.	O
</s>
<s>
There	O
was	O
also	O
a	O
replacement	O
case	O
kit	O
for	O
the	O
Amiga	B-Device
500	I-Device
made	O
by	O
Checkmate	O
Digital	O
and	O
also	O
called	O
A1500	O
.	O
</s>
<s>
The	O
Amiga	B-Device
2500	I-Device
,	O
also	O
known	O
as	O
the	O
A2500	O
,	O
similar	O
to	O
the	O
A1500	O
is	O
not	O
a	O
distinct	O
model	O
,	O
but	O
simply	O
a	O
marketing	O
name	O
for	O
an	O
Amiga	O
2000	O
with	O
a	O
different	O
base	O
configuration	O
.	O
</s>
<s>
The	O
configuration	O
of	O
an	O
A2500	O
included	O
a	O
14.3	O
MHz	O
Motorola	B-Device
68020	I-Device
or	O
25	O
MHz	O
68030-based	O
accelerator	O
card	O
.	O
</s>
<s>
68020	B-Device
versions	O
were	O
referred	O
to	O
as	O
A2500/20	O
,	O
and	O
68030	B-Device
versions	O
as	O
A2500/30	O
.	O
</s>
<s>
The	O
A2620	O
included	O
a	O
Motorola	B-General_Concept
68881	I-General_Concept
FPU	B-General_Concept
and	O
Motorola	B-General_Concept
68851	I-General_Concept
MMU	B-General_Concept
,	O
whereas	O
the	O
A2630	O
included	O
a	O
Motorola	B-General_Concept
68882	I-General_Concept
FPU	B-General_Concept
(	O
and	O
MMU	B-General_Concept
built	O
into	O
the	O
68030	B-Device
)	O
.	O
</s>
<s>
Because	O
the	O
A2500	O
has	O
a	O
Motorola	B-Device
68000	I-Device
on	O
the	O
motherboard	O
that	O
goes	O
unused	O
,	O
the	O
design	O
is	O
not	O
very	O
cost-effective	O
.	O
</s>
<s>
A	O
project	O
to	O
replace	O
it	O
with	O
a	O
68020	B-Device
on-board	O
began	O
,	O
intending	O
to	O
be	O
a	O
Zorro-II-based	O
68020	B-Device
machine	O
,	O
but	O
the	O
project	O
eventually	O
became	O
the	O
Amiga	B-Device
3000	I-Device
when	O
Dave	O
Haynie	O
sought	O
to	O
include	O
his	O
new	O
Zorro-III	O
bus	O
.	O
</s>
<s>
The	O
A2500	O
remained	O
in	O
production	O
after	O
the	O
release	O
of	O
the	O
A3000	O
,	O
primarily	O
because	O
the	O
original	O
Video	B-Device
Toaster	I-Device
will	O
not	O
fit	O
in	O
an	O
unmodified	O
A3000	O
case	O
.	O
</s>
<s>
Until	O
the	O
release	O
of	O
the	O
Video	B-Device
Toaster	I-Device
4000	I-Device
,	O
the	O
A2500	O
was	O
the	O
fastest	O
computer	O
available	O
for	O
use	O
with	O
the	O
Toaster	O
.	O
</s>
<s>
A	O
further	O
variant	O
called	O
the	O
A2500UX	O
was	O
also	O
available	O
which	O
was	O
supplied	O
with	O
Amiga	B-Operating_System
Unix	I-Operating_System
and	O
a	O
tape	O
drive	O
.	O
</s>
<s>
The	O
majority	O
of	O
A2000	O
systems	O
shipped	O
with	O
Commodore	O
's	O
Original	B-Device
Chip	I-Device
Set	I-Device
and	O
1MB	O
of	O
RAM	B-Architecture
(	O
512KB	O
of	O
"	B-Device
chip	I-Device
"	I-Device
RAM	I-Device
and	O
512KB	O
additional	O
RAM	B-Architecture
)	O
and	O
either	O
AmigaOS	B-Application
1.2	O
or	O
1.3	O
.	O
</s>
<s>
Later	O
revisions	O
shipped	O
with	O
the	O
improved	O
Enhanced	B-Device
Chip	I-Device
Set	I-Device
,	O
1MB	O
"	B-Device
chip	I-Device
"	I-Device
RAM	I-Device
and	O
AmigaOS	B-Application
2.0	O
.	O
</s>
<s>
The	O
A2000	O
shipped	O
with	O
a	O
Motorola	B-Device
68000	I-Device
CPU	B-General_Concept
,	O
running	O
at	O
7.16MHz	O
(	O
NTSC	O
)	O
or	O
7.09MHz	O
(	O
PAL	B-Language
)	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
can	O
be	O
upgraded	O
to	O
a	O
68010	B-Device
by	O
direct	O
replacement	O
.	O
</s>
<s>
Official	O
and	O
third-party	O
expansion	O
boards	O
,	O
which	O
fit	O
in	O
the	O
CPU	B-General_Concept
expansion	O
slot	O
,	O
feature	O
68020	B-Device
,	O
68030	B-Device
,	O
68040	B-Device
or	O
68060	B-General_Concept
microprocessors	O
.	O
</s>
<s>
Such	O
upgrades	O
may	O
also	O
accommodate	O
additional	O
RAM	B-Architecture
,	O
FPUs	O
,	O
MMUs	O
and	O
even	O
SCSI	B-Architecture
controllers	O
.	O
</s>
<s>
Certain	O
revisions	O
of	O
the	O
A2000	O
can	O
be	O
upgraded	O
to	O
accommodate	O
1MB	O
of	O
chip	B-Device
RAM	I-Device
by	O
installing	O
an	O
8372A	O
Agnus	B-Device
chip	O
.	O
</s>
<s>
Likewise	O
,	O
2MB	O
can	O
be	O
accommodated	O
by	O
fitting	O
an	O
8372B	O
Agnus	B-Device
chip	O
and	O
adding	O
extra	O
memory	O
.	O
</s>
<s>
There	O
is	O
a	O
practical	O
limit	O
of	O
8MB	O
of	O
additional	O
RAM	B-Architecture
without	O
the	O
use	O
of	O
a	O
CPU	B-General_Concept
expansion	O
card	O
,	O
due	O
to	O
the	O
68000	B-Device
's	O
24-bit	O
address	O
bus	O
.	O
</s>
<s>
The	O
A2000	O
brought	O
a	O
new	O
capability	O
to	O
the	O
Amiga	O
line	O
,	O
the	O
Zorro	B-Device
II	I-Device
bus	O
.	O
</s>
<s>
This	O
expansion	O
bus	O
allows	O
installation	O
of	O
compatible	O
hardware	O
through	O
the	O
AutoConfig	B-Device
standard	O
,	O
such	O
as	O
,	O
graphic	O
,	O
sound	O
,	O
and	O
network	B-Protocol
cards	I-Protocol
and	O
Parallel	B-Protocol
ATA	I-Protocol
,	O
SCSI	B-Architecture
and	O
USB	B-Protocol
controllers	O
.	O
</s>
<s>
The	O
ISA	B-Architecture
slots	I-Architecture
can	O
be	O
activated	O
by	O
use	O
of	O
a	O
bridgeboard	O
,	O
which	O
connects	O
the	O
Zorro	B-Device
II	I-Device
and	O
ISA	B-Architecture
buses	O
.	O
</s>
<s>
Such	O
bridgeboards	O
typically	O
feature	O
on-board	O
IBM	B-Device
PC	I-Device
Compatible	O
hardware	O
,	O
including	O
Intel	B-General_Concept
80286	I-General_Concept
,	O
80386	B-General_Concept
or	O
80486	B-General_Concept
microprocessors	O
allowing	O
emulation	O
of	O
an	O
entire	O
IBM-PC	B-Device
system	O
in	O
hardware	O
.	O
</s>
<s>
The	O
remaining	O
ISA	B-Architecture
slots	I-Architecture
can	O
then	O
be	O
used	O
with	O
industry	O
standard	O
hardware	O
of	O
the	O
era	O
,	O
such	O
as	O
,	O
network	B-Protocol
cards	I-Protocol
,	O
graphics	B-Device
cards	I-Device
and	O
hard	B-Device
drive	I-Device
controllers	O
.	O
</s>
<s>
In	O
some	O
A2000	O
models	O
,	O
the	O
two	O
8-bit	O
ISA	B-Architecture
slots	I-Architecture
can	O
also	O
be	O
upgraded	O
to	O
16-bit	O
by	O
fitting	O
extension	O
edge	O
connectors	O
.	O
</s>
<s>
This	O
allows	O
use	O
of	O
dedicated	O
genlocks	O
,	O
display	O
deinterlacers	O
,	O
and	O
video-switching	O
and	O
effects	O
systems	O
such	O
as	O
NewTek	O
's	O
Video	B-Device
Toaster	I-Device
.	O
</s>
<s>
Attribute	O
SpecificationProcessorMotorola	O
68000	B-Device
at	O
7.16	O
MHz	O
(	O
NTSC	O
)	O
or	O
7.09	O
MHz	O
(	O
PAL	B-Language
)	O
RAM1	O
MB	O
consisting	O
of	O
either	O
:	O
</s>
<s>
ECS	B-Device
only	O
graphic	O
modes	O
:	O
</s>
