<s>
MacWorks	B-Device
Plus	I-Device
was	O
a	O
complete	O
implementation	O
(	O
port	O
)	O
of	O
the	O
Macintosh	B-Device
Plus	I-Device
128K	O
ROM	O
on	O
the	O
Apple	B-Device
Lisa	I-Device
and	O
Macintosh	B-Device
XL	I-Device
computer	O
systems	O
,	O
and	O
introduced	O
in	O
August	O
1988	O
.	O
</s>
<s>
It	O
was	O
developed	O
for	O
Sun	O
Remarketing	O
of	O
Cache	O
Valley	O
,	O
Utah	O
,	O
under	O
license	O
from	O
Apple	O
Inc.	O
,	O
by	O
a	O
contract	O
developer	O
named	O
Chuck	O
Lukaszewski	O
,	O
who	O
was	O
responsible	O
for	O
versions	O
up	O
through	O
1.1(h )	O
,	O
which	O
supported	O
up	O
to	O
Macintosh	B-Application
System	I-Application
6.0.3	O
.	O
</s>
<s>
Dafax	O
Processing	O
Corp	O
.	O
with	O
the	O
assistance	O
of	O
Query	O
Engineering	O
,	O
Inc	O
.	O
then	O
further	O
developed	O
the	O
environment	O
to	O
MacWorks	B-Device
Plus	I-Device
II	O
,	O
which	O
continued	O
Macintosh	B-Application
system	I-Application
support	O
up	O
to	O
System	B-Protocol
6.0.8	I-Protocol
with	O
the	O
Basic	O
version	O
,	O
and	O
introduced	O
a	O
Pro	O
version	O
to	O
extend	O
support	O
to	O
the	O
maximum	O
possible	O
for	O
any	O
68000	B-Device
processor	O
:	O
System	B-Operating_System
7.5.5	I-Operating_System
.	O
</s>
<s>
Prior	O
to	O
MacWorks	B-Device
Plus	I-Device
,	O
the	O
maximum	O
system	O
supported	O
by	O
its	O
predecessor	O
MacWorks	B-Application
XL	I-Application
was	O
System	O
3.2	O
.	O
</s>
<s>
The	O
design	O
objective	O
for	O
MacWorks	B-Device
Plus	I-Device
was	O
100%	O
compatibility	O
with	O
software	O
that	O
ran	O
on	O
the	O
Macintosh	B-Device
Plus	I-Device
,	O
which	O
at	O
the	O
time	O
was	O
Apple	O
's	O
flagship	O
product	O
.	O
</s>
<s>
This	O
was	O
a	O
technically	O
challenging	O
goal	O
because	O
other	O
than	O
sharing	O
the	O
same	O
Motorola	B-Device
68000	I-Device
processor	I-Device
,	O
the	O
underlying	O
hardware	O
architectures	O
of	O
the	O
two	O
systems	O
were	O
radically	O
different	O
.	O
</s>
<s>
In	O
order	O
to	O
understand	O
how	O
MacWorks	B-Device
Plus	I-Device
worked	O
,	O
it	O
is	O
easiest	O
to	O
divide	O
the	O
discussion	O
into	O
three	O
areas	O
:	O
hardware	O
interface	O
,	O
memory	O
model	O
and	O
bootstrap	O
protocol	O
.	O
</s>
<s>
These	O
were	O
the	O
hardware-dependent	O
aspects	O
of	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
at	O
the	O
time	O
.	O
</s>
<s>
The	O
simplest	O
method	O
of	O
transporting	O
the	O
Mac	B-Application
OS	I-Application
to	O
another	O
machine	O
was	O
to	O
emulate	O
them	O
completely	O
.	O
</s>
<s>
This	O
is	O
what	O
was	O
done	O
with	O
MacWorks	B-Device
Plus	I-Device
.	O
</s>
<s>
The	O
goal	O
was	O
made	O
possible	O
by	O
the	O
existence	O
of	O
a	O
hardware	O
abstraction	O
layer	O
in	O
the	O
Macintosh	B-Device
Toolbox	I-Device
in	O
the	O
original	O
Macintosh	O
ROM	O
,	O
and	O
a	O
hardware	O
Memory	B-General_Concept
Management	I-General_Concept
Unit	I-General_Concept
(	O
MMU	O
)	O
in	O
the	O
Lisa	B-Device
.	O
</s>
<s>
Through	O
a	O
complete	O
package	O
of	O
device	O
drivers	O
that	O
fully	O
implemented	O
the	O
Macintosh	B-Device
Toolbox	I-Device
Application	O
Programming	O
Interface	O
(	O
APIs	O
)	O
,	O
MacWorks	B-Device
Plus	I-Device
essentially	O
tricked	O
the	O
128K	O
ROM	O
code	O
into	O
thinking	O
it	O
was	O
running	O
on	O
an	O
actual	O
Macintosh	O
.	O
</s>
<s>
It	O
was	O
also	O
necessary	O
to	O
completely	O
simulate	O
the	O
memory	O
address	O
space	O
of	O
a	O
Macintosh	B-Device
Plus	I-Device
,	O
including	O
the	O
behavior	O
of	O
certain	O
illegal	O
addresses	O
that	O
were	O
deliberately	O
exploited	O
by	O
certain	O
applications	O
(	O
primarily	O
games	O
)	O
.	O
</s>
<s>
Fortunately	O
,	O
while	O
the	O
Macintosh	O
memory	O
manager	O
circuitry	O
was	O
not	O
programmable	O
,	O
the	O
Lisa	B-Device
featured	O
a	O
fully	O
programmable	O
hardware	O
MMU	O
which	O
was	O
a	O
legacy	O
of	O
the	O
minicomputer	O
roots	O
of	O
its	O
designers	O
.	O
</s>
<s>
Finally	O
,	O
bootloaders	O
were	O
written	O
for	O
all	O
available	O
floppy	O
disk	O
and	O
hard	O
disk	O
models	O
that	O
were	O
compatible	O
with	O
the	O
Lisa	B-Device
.	O
</s>
<s>
MacWorks	B-Device
Plus	I-Device
consisted	O
of	O
some	O
23,000	O
lines	O
of	O
source	O
code	O
for	O
the	O
Lisa-dependent	O
hardware	O
interface	O
and	O
bootstrap	O
code	O
,	O
plus	O
an	O
image	O
of	O
the	O
128K	O
ROM	O
that	O
was	O
licensed	O
from	O
Apple	O
.	O
</s>
<s>
It	O
also	O
included	O
a	O
standalone	O
installer	O
and	O
a	O
Control	O
Panel	O
that	O
enabled	O
a	O
user	O
to	O
adjust	O
certain	O
Lisa	B-Device
specific	O
features	O
from	O
inside	O
the	O
Mac	B-Application
OS	I-Application
user	O
interface	O
.	O
</s>
