<s>
1541	B-Device
Ultimate	I-Device
(	O
often	O
abbreviated	O
1541U	O
)	O
is	O
a	O
peripheral	O
,	O
primarily	O
an	O
emulated	B-Application
floppy	B-Device
disk	I-Device
and	O
cartridge	B-Protocol
emulator	B-Application
based	O
on	O
the	O
FPGA	B-Architecture
Xilinx	O
XC3S250E	O
,	O
for	O
the	O
Commodore	O
64	O
home	O
computer	O
.	O
</s>
<s>
The	O
unit	O
is	O
developed	O
by	O
Gideon	O
Zweijtzer	O
and	O
is	O
a	O
cartridge	B-Protocol
that	O
can	O
emulate	O
other	O
cartridges	B-Protocol
such	O
as	O
the	O
Commodore	B-General_Concept
REU	I-General_Concept
,	O
Action	B-Device
Replay	I-Device
,	O
The	B-Device
Final	I-Device
Cartridge	I-Device
III	I-Device
,	O
Super	O
Snapshot	O
V5	O
,	O
Retro	O
Replay	O
or	O
TurboAss	O
with	O
Codenet-support	O
,	O
and	O
an	O
almost	O
fully	O
compatible	O
(	O
including	O
JiffyDOS	O
support	O
FPGA-cloned	O
Commodore	B-Device
1541	I-Device
(	O
including	O
1541	O
,	O
1541C	O
,	O
and	O
1541	O
II	O
models	O
)	O
floppy	B-Device
disk	I-Device
unit	O
that	O
can	O
use	O
Commodore	O
64-compatible	O
files	O
like	O
.D64/.G64	O
disc	O
images	O
or	O
.PRG	O
files	O
via	O
a	O
SD	B-Device
card	I-Device
reader	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
1541	B-Device
Ultimate	I-Device
is	O
suitable	O
for	O
making	O
archives	O
of	O
floppy	B-Device
disks	I-Device
.	O
</s>
<s>
All	O
units	O
after	O
the	O
initial	O
production	O
have	O
32	O
megabytes	O
of	O
RAM	B-Architecture
,	O
while	O
the	O
original	O
production	O
run	O
only	O
had	O
16	O
megabytes	O
.	O
</s>
<s>
The	O
1541	B-Device
Ultimate	I-Device
is	O
capable	O
of	O
running	O
both	O
CP/M	B-Application
and	O
GEOS	B-Device
.	O
</s>
<s>
In	O
2010	O
,	O
the	O
1541	B-Device
Ultimate	I-Device
II	O
was	O
developed	O
.	O
</s>
<s>
The	O
Ultimate	O
II	O
is	O
about	O
30%	O
smaller	O
than	O
the	O
1541	B-Device
Ultimate	I-Device
,	O
comes	O
in	O
a	O
plastic	O
case	O
,	O
and	O
adds	O
support	O
for	O
dual	O
SIDs	O
(	O
plus	O
a	O
SID/MOD	O
player	O
)	O
,	O
a	O
USB	B-Protocol
host	O
controller	O
,	O
tape	B-Application
emulation	I-Application
via	O
a	O
tape	O
adapter	O
(	O
though	O
use	O
with	O
a	O
Commodore	O
128D	O
requires	O
modification	O
)	O
,	O
a	O
real-time	O
clock	O
(	O
for	O
accurate	O
file	O
date	O
and	O
time	O
)	O
,	O
and	O
the	O
SD	B-Device
card	I-Device
slot	O
is	O
replaced	O
by	O
a	O
microSD	O
card	O
slot	O
.	O
</s>
<s>
In	O
addition	O
,	O
all	O
firmware	O
and	O
VHDL	B-Language
code	O
for	O
the	O
Ultimate	O
II	O
is	O
available	O
under	O
an	O
open	B-Application
source	I-Application
GPLv3	O
license	B-License
,	O
allowing	O
hobbyists	O
and	O
others	O
to	O
freely	O
modify	O
all	O
aspects	O
of	O
its	O
functionality	O
,	O
including	O
the	O
FPGA-emulated	O
hardware	O
.	O
</s>
<s>
The	O
1541	B-Device
Ultimate	I-Device
has	O
an	O
option	O
for	O
on-board	O
Ethernet	O
,	O
while	O
the	O
1541	B-Device
Ultimate	I-Device
II	O
supports	O
Ethernet	O
via	O
a	O
compatible	O
USB	B-Protocol
to	O
Ethernet	O
adapter	O
.	O
</s>
<s>
Removal	O
of	O
the	O
MicroSD	O
slot	O
,	O
More	O
USB	B-Protocol
ports	O
,	O
Integrated	O
Ethernet	O
,	O
Dual	O
Flash	O
,	O
Integrated	O
Speaker	O
,	O
External	O
power	O
supply	O
connector	O
with	O
auto-switch	O
over	O
circuit	O
,	O
Improved	O
power	O
supply	O
circuits	O
,	O
and	O
a	O
slightly	O
bigger	O
and	O
faster	O
FPGA	B-Architecture
,	O
as	O
to	O
control	O
the	O
new	O
features	O
.	O
</s>
