<s>
Pascal	B-Device
MicroEngine	I-Device
is	O
a	O
series	O
of	O
microcomputer	B-Architecture
products	O
manufactured	O
by	O
Western	O
Digital	O
from	O
1979	O
through	O
the	O
mid-1980s	O
,	O
designed	O
specifically	O
to	O
run	O
the	O
UCSD	B-Language
p-System	I-Language
efficiently	O
.	O
</s>
<s>
Compared	O
to	O
other	O
microcomputers	B-Architecture
,	O
which	O
use	O
a	O
machine	B-Language
language	I-Language
p-code	B-Language
interpreter	B-Application
,	O
the	O
Pascal	B-Device
MicroEngine	I-Device
has	O
its	O
interpreter	B-Application
implemented	O
in	O
microcode	B-Device
;	O
p-code	B-Language
is	O
its	O
machine	B-Language
language	I-Language
.	O
</s>
<s>
The	O
most	O
common	O
programming	O
language	O
used	O
on	O
the	O
p-System	B-Language
is	O
Pascal	B-Application
.	O
</s>
<s>
The	O
MicroEngine	O
runs	O
a	O
special	O
release	O
III	O
p-System	B-Language
.	O
</s>
<s>
The	O
MicroEngine	O
chipset	O
was	O
based	O
on	O
the	O
MCP-1600	B-General_Concept
chipset	O
,	O
which	O
formed	O
the	O
basis	O
of	O
the	O
DEC	O
LSI-11	O
low-end	O
minicomputer	B-Architecture
and	O
the	O
WD16	B-General_Concept
processor	O
used	O
by	O
Alpha	O
Microsystems	O
(	O
each	O
using	O
different	O
microcode	B-Device
)	O
.	O
</s>
<s>
One	O
of	O
the	O
well	O
regarded	O
systems	O
was	O
the	O
S-100	B-Architecture
bus	I-Architecture
based	O
dual	B-General_Concept
processor	I-General_Concept
cards	O
developed	O
by	O
Digicomp	O
Research	O
of	O
Ithaca	O
,	O
NY	O
.	O
</s>
<s>
A	O
typical	O
configuration	O
was	O
a	O
Digicomp	O
dual	B-General_Concept
processor	I-General_Concept
board	O
set	O
,	O
containing	O
a	O
Zilog	B-General_Concept
Z80	I-General_Concept
and	O
a	O
bipolar	O
memory	O
mapper	O
harnessed	O
to	O
a	O
microengine	O
chipset	O
on	O
the	O
second	O
board	O
,	O
linked	O
by	O
a	O
direct	O
cable	O
.	O
</s>
<s>
The	O
sole	O
configuration	O
known	O
to	O
be	O
still	O
running	O
in	O
2018	O
and	O
documented	O
on	O
the	O
web	O
is	O
described	O
by	O
Marcus	O
Wigan	O
and	O
contains	O
312	O
kB	O
of	O
memory	O
,	O
RAM	O
disc	O
support	O
through	O
a	O
modified	O
Z80	B-General_Concept
BIOS	B-Operating_System
(	O
written	O
by	O
Tom	O
Evans	O
)	O
taking	O
advantage	O
of	O
the	O
memory	O
mapping	O
chip	O
on	O
the	O
Z80	B-General_Concept
board	O
,	O
and	O
using	O
the	O
UCSD	B-Language
Pascal	I-Language
III	O
version	O
of	O
the	O
operating	O
system	O
tuned	O
specifically	O
for	O
the	O
WD	O
chipset	O
-	O
once	O
the	O
Microengine	O
had	O
booted	O
the	O
ram-disc	O
was	O
available	O
.	O
</s>
<s>
A	O
software	O
facility	O
within	O
UCSD	B-Language
Pascal	I-Language
allowed	O
the	O
system	O
to	O
copy	O
the	O
entire	O
operating	O
system	O
to	O
the	O
ram	O
disc	O
and	O
transfer	O
control	O
to	O
it	O
.	O
</s>
<s>
This	O
use	O
of	O
a	O
Z80	B-General_Concept
BIOS	B-Operating_System
to	O
handle	O
all	O
the	O
devices	O
,	O
allowed	O
the	O
use	O
of	O
a	O
range	O
of	O
floppy	O
discs	O
,	O
I/O	O
boards	O
and	O
hard	B-General_Concept
disk	I-General_Concept
controllers	I-General_Concept
.	O
</s>
<s>
The	O
performance	O
of	O
this	O
Microengine	O
on	O
a	O
series	O
of	O
simply	O
Interface	O
Age	O
benchmarks	O
(	O
originally	O
designed	O
for	O
BASIC	O
programs	O
)	O
is	O
documented	O
in	O
an	O
Australian	O
Computer	O
Society	O
,	O
MICSIG	O
,	O
paper	O
presented	O
at	O
the	O
National	O
Conference	O
on	O
Microcomputer	B-Architecture
Software	O
,	O
Canberra	O
,	O
ACT	O
presented	O
in	O
June	O
1982	O
,	O
along	O
with	O
a	O
wide	O
range	O
of	O
other	O
contemporary	O
machines	O
and	O
compilers	B-Language
,	O
including	O
Z80	B-General_Concept
systems	O
supported	O
by	O
the	O
9511	O
APU	O
chip	O
hosted	O
in	O
the	O
Digicomp	O
S-100	O
Microengine	O
system	O
that	O
he	O
used	O
.	O
</s>
<s>
At	O
the	O
time	O
of	O
introduction	O
,	O
the	O
only	O
competitors	O
were	O
8-bit	O
processors	O
(	O
mainly	O
Intel	B-General_Concept
8080	I-General_Concept
,	O
Z80	B-General_Concept
,	O
and	O
MOS	B-General_Concept
Technology	I-General_Concept
6502	I-General_Concept
based	O
systems	O
)	O
.	O
</s>
<s>
The	O
MicroEngine	O
could	O
compile	B-Language
Pascal	B-Application
source	O
code	O
in	O
a	O
fraction	O
of	O
the	O
time	O
(	O
typically	O
about	O
1/10	O
)	O
required	O
by	O
contemporaries	O
.	O
</s>
<s>
Fast	O
compilation	B-Language
made	O
the	O
MicroEngine	O
especially	O
nice	O
as	O
a	O
developer	O
's	O
machine	O
,	O
and	O
the	O
inclusion	O
of	O
a	O
semaphore	B-Operating_System
primitive	O
in	O
the	O
microcode	B-Device
was	O
particularly	O
useful	O
for	O
multi	O
user	O
enhancements	O
,	O
which	O
were	O
developed	O
in	O
Melbourne	O
for	O
the	O
Canberra	O
Australia-based	O
Ortex	O
Company	O
,	O
extended	O
to	O
be	O
a	O
multiuser	O
system	O
and	O
often	O
sold	O
with	O
a	O
bundled	O
pharmacy	O
management	O
system	O
,	O
also	O
delivered	O
on	O
the	O
Sage	O
IV	O
computers	O
under	O
UCSD	B-Language
Pascal	I-Language
IV	O
and	O
enabled	O
as	O
a	O
multiuser	O
system	O
using	O
the	O
Sage	O
multiuser	O
bios	B-Operating_System
rather	O
than	O
by	O
extending	O
UCSD	B-Language
Pascal	I-Language
IV	O
to	O
add	O
a	O
semaphore	B-Operating_System
.	O
</s>
<s>
This	O
performance	O
advantage	O
was	O
eroded	O
by	O
the	O
later	O
availability	O
of	O
p-code	B-Language
to	O
native	O
machine	B-Language
code	I-Language
translators	O
,	O
and	O
mainstream	O
16-bit	O
microprocessors	O
such	O
as	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
and	O
Motorola	B-Device
68000	I-Device
.	O
</s>
<s>
Between	O
a	O
damaged	O
reputation	O
and	O
the	O
introduction	O
of	O
the	O
IBM	B-Device
PC	I-Device
,	O
in	O
the	O
end	O
the	O
MicroEngine	O
was	O
only	O
modestly	O
successful	O
.	O
</s>
<s>
A	O
group	O
led	O
by	O
David	O
A	O
.	O
Fisher	O
developed	O
the	O
third	O
validated	O
Ada	B-Language
compiler	B-Language
using	O
the	O
Modular	O
MicroEngine	O
.	O
</s>
<s>
for	O
version	O
17.1	O
of	O
the	O
Ada	B-Language
verification	O
system	O
then	O
in	O
use	O
.	O
</s>
<s>
This	O
compiler	B-Language
was	O
later	O
transferred	O
to	O
mainframe/minicomputers	O
under	O
the	O
name	O
of	O
GenSoft	O
Ada	B-Language
,	O
and	O
ran	O
in	O
an	O
emulator	O
of	O
the	O
Microengine	O
under	O
the	O
MicroEngine-specific	O
UCSD	O
3	O
operating	O
system	O
.	O
</s>
<s>
Copies	O
of	O
the	O
Prime	O
computer	O
version	O
are	O
known	O
to	O
be	O
held	O
by	O
M	O
R	O
Wigan	O
,	O
who	O
also	O
holds	O
a	O
zero	O
price	O
licence	O
for	O
the	O
full	O
MicroEngine	O
Ada	B-Language
system	O
and	O
UCSD	O
3	O
Operating	O
system	O
used	O
for	O
the	O
Modular	O
Microengine	O
,	O
as	O
well	O
as	O
the	O
three	O
Modular	O
MicroEngines	O
used	O
to	O
create	O
the	O
17.1	O
Ada	B-Language
,	O
and	O
all	O
the	O
development	O
8	O
"	O
floppy	O
discs	O
.	O
</s>
<s>
Ada	B-Language
was	O
the	O
only	O
other	O
full	O
programming	O
language	O
available	O
.	O
</s>
<s>
John	O
Lloyd	O
of	O
the	O
University	O
of	O
Melbourne	O
created	O
an	O
early	O
version	O
of	O
his	O
Prolog	O
for	O
this	O
system	O
and	O
both	O
Basic	O
and	O
Fortran	O
77	O
compilers	B-Language
were	O
ported	O
from	O
other	O
UCSD	B-Language
P-system	I-Language
implementations	O
at	O
various	O
times	O
,	O
but	O
not	O
widely	O
distributed	O
.	O
</s>
<s>
Due	O
to	O
limited	O
memory	O
(	O
62K	O
16-bit	O
words	O
,	O
the	O
last	O
2K	O
words	O
being	O
reserved	O
for	O
memory-mapped	B-Architecture
I/O	I-Architecture
and	O
PROM	B-General_Concept
for	O
the	O
hard	O
disk	O
bootstrap	O
code	O
)	O
only	O
very	O
small	O
Ada	B-Language
programs	O
could	O
be	O
compiled	B-Language
.	O
</s>
<s>
At	O
one	O
point	O
in	O
the	O
compilation	B-Language
the	O
compiler	B-Language
swapped	O
the	O
operating	O
system	O
out	O
to	O
disk	O
,	O
to	O
gain	O
just	O
a	O
little	O
more	O
room	O
.	O
</s>
<s>
This	O
UCSD-based	O
Ada	B-Language
was	O
later	O
redeveloped	O
for	O
the	O
Sage	O
4	O
by	O
TeleSoft	O
in	O
San	O
Diego	O
.	O
</s>
