<s>
The	O
Z8000	O
(	O
"	O
zee	O
-	O
or	O
zed-eight-thousand	O
"	O
)	O
is	O
a	O
16-bit	B-Device
microprocessor	B-Architecture
introduced	O
by	O
Zilog	O
in	O
early	O
1979	O
.	O
</s>
<s>
In	O
contrast	O
to	O
most	O
designs	O
of	O
the	O
era	O
,	O
the	O
Z8000	O
did	O
not	O
use	O
microcode	B-Device
which	O
allowed	O
it	O
to	O
be	O
implemented	O
in	O
only	O
17,500	O
transistors	O
.	O
</s>
<s>
The	O
Z8000	O
was	O
not	O
Z80-compatible	O
,	O
although	O
it	O
featured	O
many	O
of	O
the	O
well-received	O
design	O
notes	O
that	O
made	O
the	O
Z80	B-General_Concept
popular	O
.	O
</s>
<s>
Among	O
these	O
was	O
the	O
ability	O
for	O
its	O
registers	B-General_Concept
to	O
be	O
combined	O
and	O
used	O
as	O
a	O
single	O
larger	O
register	O
-	O
while	O
the	O
Z80	B-General_Concept
allowed	O
two	O
8-bit	O
registers	B-General_Concept
to	O
be	O
used	O
as	O
a	O
single	O
16-bit	B-Device
register	O
,	O
the	O
Z8000	O
expanded	O
this	O
by	O
allowing	O
two	O
16-bit	B-Device
registers	B-General_Concept
to	O
operate	O
as	O
a	O
32-bit	O
register	O
,	O
or	O
four	O
to	O
operate	O
as	O
a	O
64-bit	O
register	O
.	O
</s>
<s>
These	O
combined	O
registers	B-General_Concept
were	O
particularly	O
useful	O
for	O
mathematical	O
operations	O
.	O
</s>
<s>
Although	O
it	O
was	O
an	O
attractive	O
design	O
for	O
its	O
era	O
,	O
and	O
saw	O
some	O
use	O
in	O
the	O
early	O
1980s	O
,	O
it	O
was	O
never	O
as	O
popular	O
as	O
the	O
Z80	B-General_Concept
.	O
</s>
<s>
It	O
was	O
released	O
after	O
the	O
16-bit	B-Device
Intel	B-General_Concept
8086	I-General_Concept
(	O
April	O
1978	O
)	O
and	O
the	O
same	O
time	O
as	O
the	O
less-expensive	O
Intel	B-Device
8088	I-Device
,	O
and	O
only	O
months	O
before	O
the	O
Motorola	B-Device
68000	I-Device
(	O
September	O
1979	O
)	O
,	O
which	O
had	O
a	O
32-bit	O
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
and	O
was	O
roughly	O
twice	O
as	O
fast	O
.	O
</s>
<s>
The	O
Zilog	B-Device
Z80000	I-Device
was	O
a	O
32-bit	O
follow-on	O
design	O
,	O
launched	O
in	O
1986	O
.	O
</s>
<s>
The	O
Z8000	O
initially	O
shipped	O
in	O
two	O
versions	O
;	O
the	O
Z8001	O
with	O
a	O
full	O
23-bit	O
external	O
address	B-Architecture
bus	I-Architecture
to	O
allow	O
it	O
to	O
access	O
up	O
to	O
8	O
megabytes	O
of	O
memory	O
,	O
and	O
the	O
Z8002	O
,	O
which	O
supported	O
only	O
16-bit	B-Device
addressing	O
to	O
allow	O
64	O
kilobytes	O
of	O
memory	O
.	O
</s>
<s>
This	O
allowed	O
the	O
Z8002	O
to	O
have	O
eight	O
fewer	O
pins	O
,	O
shipping	O
in	O
a	O
smaller	O
40-pin	O
DIP	B-Algorithm
format	O
that	O
made	O
it	O
less	O
expensive	O
to	O
implement	O
.	O
</s>
<s>
These	O
versions	O
were	O
designed	O
to	O
provide	O
improved	O
support	O
for	O
virtual	B-Architecture
memory	I-Architecture
,	O
adding	O
new	O
status	O
registers	B-General_Concept
to	O
indicate	O
segmentation	B-Error_Name
faults	I-Error_Name
(	O
test	O
and	O
set	O
)	O
and	O
provide	O
an	O
abort	O
capability	O
.	O
</s>
<s>
The	O
register	B-General_Concept
set	I-General_Concept
consisted	O
of	O
sixteen	O
16-bit	B-Device
general	O
purpose	O
registers	B-General_Concept
,	O
labeled	O
R0	O
through	O
R15	O
.	O
</s>
<s>
The	O
registers	B-General_Concept
can	O
be	O
concatenated	O
into	O
eight	O
32-bit	O
registers	B-General_Concept
,	O
labeled	O
RR0/RR2/../RR14	O
,	O
or	O
into	O
four	O
64-bit	O
registers	B-General_Concept
,	O
labeled	O
RQ0/RQ4/RQ8/RQ12	O
.	O
</s>
<s>
The	O
first	O
eight	O
registers	B-General_Concept
can	O
be	O
also	O
subdivided	O
into	O
sixteen	O
8-bit	O
registers	B-General_Concept
,	O
labeled	O
RL0	O
though	O
RL7	O
for	O
the	O
lower	O
byte	O
and	O
RH0	O
through	O
RH7	O
for	O
the	O
upper	O
(	O
high	O
)	O
byte	O
.	O
</s>
<s>
Register	O
R15	O
is	O
designated	O
as	O
stack	B-Application
pointer	O
.	O
</s>
<s>
On	O
the	O
Z8001	O
,	O
register	O
R14	O
is	O
used	O
to	O
add	O
a	O
fixed	O
offset	O
to	O
the	O
stack	B-Application
pointer	O
,	O
and	O
the	O
program	B-General_Concept
counter	I-General_Concept
is	O
expanded	O
to	O
32-bits	O
to	O
include	O
a	O
similar	O
offset	O
.	O
</s>
<s>
There	O
was	O
both	O
a	O
user	B-Operating_System
mode	I-Operating_System
(	O
"	O
normal	O
"	O
)	O
and	O
a	O
supervisor	O
mode	O
,	O
selected	O
by	O
bit	O
14	O
in	O
the	O
flag	O
register	O
.	O
</s>
<s>
In	O
supervisor	O
mode	O
,	O
the	O
stack	B-Application
registers	B-General_Concept
point	O
to	O
the	O
system	O
stack	B-Application
and	O
all	O
privileged	O
instructions	O
are	O
available	O
.	O
</s>
<s>
In	O
user	B-Operating_System
mode	I-Operating_System
,	O
the	O
stack	B-Application
registers	B-General_Concept
point	O
to	O
the	O
normal	O
stack	B-Application
and	O
all	O
privileged	O
instructions	O
will	O
generate	O
a	O
fault	O
.	O
</s>
<s>
Having	O
separate	O
modes	O
and	O
stacks	B-Application
greatly	O
adds	O
to	O
the	O
performance	O
of	O
context	B-Operating_System
switches	I-Operating_System
between	O
user	O
programs	O
and	O
an	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Like	O
the	O
Z80	B-General_Concept
before	O
it	O
,	O
the	O
Z8000	O
included	O
a	O
system	O
to	O
automatically	O
refresh	O
dynamic	O
RAM	O
.	O
</s>
<s>
In	O
most	O
systems	O
this	O
is	O
normally	O
handled	O
by	O
the	O
video	B-General_Concept
display	I-General_Concept
controller	I-General_Concept
or	O
external	O
logic	O
.	O
</s>
<s>
The	O
Z8000	O
used	O
a	O
segmented	B-General_Concept
memory	I-General_Concept
map	O
,	O
with	O
a	O
7-bit	O
"	O
segment	O
number	O
"	O
and	O
a	O
16-bit	B-Device
offset	O
.	O
</s>
<s>
Instructions	O
could	O
only	O
directly	O
access	O
a	O
16-bit	B-Device
offset	O
.	O
</s>
<s>
This	O
allowed	O
the	O
instruction	O
format	O
to	O
be	O
smaller	O
;	O
a	O
system	O
with	O
direct	O
access	O
to	O
a	O
23-bit	O
address	O
would	O
need	O
to	O
read	O
three	O
bytes	O
(	O
24-bits	O
)	O
from	O
memory	O
for	O
every	O
address	O
referred	O
to	O
in	O
the	O
code	O
,	O
thus	O
requiring	O
two	O
reads	O
on	O
a	O
16-bit	B-Device
bus	O
.	O
</s>
<s>
With	O
segments	O
,	O
the	O
addresses	O
needed	O
only	O
a	O
single	O
16-bit	B-Device
read	O
which	O
is	O
then	O
added	O
to	O
a	O
segment	O
number	O
to	O
produce	O
the	O
complete	O
address	O
.	O
</s>
<s>
The	O
segment	O
number	O
only	O
needed	O
to	O
be	O
updated	O
when	O
the	O
data	O
crossed	O
the	O
16-bit/64KB	O
boundaries	O
.	O
</s>
<s>
This	O
consisted	O
of	O
an	O
upper	O
16-bit	B-Device
word	O
with	O
a	O
leading	O
0	O
in	O
bit	O
15	O
,	O
the	O
7-bit	O
segment	O
number	O
,	O
and	O
then	O
8	O
zeros	O
.	O
</s>
<s>
This	O
required	O
more	O
memory	O
to	O
store	O
,	O
as	O
each	O
23-bit	O
address	O
used	O
up	O
32	O
bits	O
of	O
register	O
space	O
,	O
but	O
allowed	O
the	O
addresses	O
to	O
be	O
cleanly	O
stored	O
in	O
the	O
16-bit	B-Device
registers	B-General_Concept
and	O
can	O
be	O
more	O
easily	O
pushed	O
and	O
popped	O
from	O
the	O
stack	B-Application
,	O
which	O
occurred	O
in	O
16-bit	B-Device
words	O
.	O
</s>
<s>
The	O
optional	O
48-pin	O
Z8010	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
(	O
MMU	O
)	O
expanded	O
the	O
memory	O
map	O
to	O
16MB	O
by	O
translating	O
the	O
23-bit	O
address	O
from	O
the	O
CPU	O
to	O
a	O
24-bit	O
one	O
.	O
</s>
<s>
When	O
the	O
CPU	O
attempted	O
to	O
access	O
a	O
particular	O
segment	O
,	O
the	O
Z8010	O
would	O
translate	O
that	O
into	O
an	O
8-bit	O
address	O
on	O
the	O
address	B-Architecture
bus	I-Architecture
,	O
and	O
then	O
pass	O
the	O
16-bit	B-Device
offset	O
on	O
unchanged	O
.	O
</s>
<s>
With	O
the	O
release	O
of	O
the	O
Z8003/Z8004	O
,	O
the	O
Z8015	O
was	O
added	O
to	O
the	O
lineup	O
,	O
adding	O
paged	B-Architecture
memory	I-Architecture
support	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
Z8015	O
expands	O
the	O
segment	O
number	O
from	O
7	O
to	O
12	O
bits	O
,	O
and	O
then	O
using	O
those	O
as	O
the	O
most	O
significant	O
bits	O
of	O
the	O
23-bit	O
overall	O
address	O
,	O
overriding	O
the	O
upper	O
bits	O
of	O
the	O
original	O
16-bit	B-Device
offset	O
.	O
</s>
<s>
The	O
advantage	O
to	O
this	O
access	O
scheme	O
is	O
that	O
it	O
is	O
easy	O
to	O
read	O
or	O
write	O
2KB	O
blocks	O
to	O
a	O
hard	B-Device
drive	I-Device
,	O
so	O
this	O
pattern	O
more	O
closely	O
matches	O
what	O
will	O
ultimately	O
happen	O
on	O
a	O
segfault	B-Error_Name
.	O
</s>
<s>
One	O
uncommon	O
feature	O
found	O
on	O
the	O
Z8000	O
,	O
more	O
commonly	O
associated	O
with	O
minicomputers	B-Architecture
,	O
was	O
direct	O
support	O
for	O
vectored	B-Architecture
interrupts	I-Architecture
.	O
</s>
<s>
Interrupts	B-Application
are	O
used	O
by	O
external	O
devices	O
to	O
notify	O
the	O
processor	O
that	O
some	O
condition	O
has	O
been	O
met	O
;	O
a	O
common	O
use	O
is	O
to	O
indicate	O
that	O
data	O
from	O
a	O
slow	O
process	O
like	O
reading	O
a	O
floppy	B-Device
disk	I-Device
is	O
now	O
available	O
and	O
the	O
CPU	O
can	O
read	O
the	O
data	O
into	O
memory	O
.	O
</s>
<s>
Normally	O
on	O
small	O
machines	O
,	O
an	O
interrupt	B-Application
causes	O
special	O
code	O
to	O
run	O
that	O
examines	O
various	O
status	O
bits	O
and	O
memory	O
locations	O
to	O
decide	O
what	O
device	O
actually	O
called	O
the	O
interrupt	B-Application
and	O
why	O
.	O
</s>
<s>
In	O
some	O
designs	O
,	O
especially	O
those	O
intended	O
for	O
realtime	B-General_Concept
computing	I-General_Concept
,	O
a	O
bit	O
of	O
memory	O
is	O
set	O
aside	O
as	O
a	O
set	O
of	O
pointers	O
,	O
or	O
vectors	O
,	O
to	O
the	O
code	O
handling	O
a	O
particular	O
device	O
.	O
</s>
<s>
The	O
devices	O
causing	O
the	O
interrupt	B-Application
then	O
set	O
some	O
state	O
,	O
typically	O
via	O
pins	O
on	O
the	O
CPU	O
,	O
to	O
indicate	O
a	O
particular	O
interrupt	B-Application
number	O
,	O
N	O
.	O
When	O
the	O
interrupt	B-Application
is	O
called	O
,	O
the	O
CPU	O
immediately	O
jumps	O
through	O
Nth	O
entry	O
in	O
the	O
table	O
,	O
avoiding	O
any	O
need	O
to	O
decode	O
the	O
interrupt	B-Application
.	O
</s>
<s>
This	O
can	O
greatly	O
speed	O
up	O
the	O
interrupt	B-Application
servicing	O
by	O
avoiding	O
having	O
to	O
run	O
additional	O
operations	O
,	O
while	O
also	O
simplifying	O
the	O
interrupt	B-Application
handling	I-Application
code	O
.	O
</s>
<s>
This	O
was	O
similar	O
to	O
a	O
memory	O
address	O
in	O
a	O
register	O
,	O
consisting	O
of	O
two	O
16-bit	B-Device
values	O
with	O
the	O
upper	O
16-bits	B-Device
holding	O
the	O
segment	O
number	O
.	O
</s>
<s>
The	O
lower	O
16-bits	B-Device
were	O
then	O
divided	O
in	O
half	O
,	O
the	O
upper	O
8-bit	O
containing	O
an	O
offset	O
and	O
the	O
lower	O
8-bits	O
empty	O
.	O
</s>
<s>
To	O
call	O
a	O
particular	O
vector	O
,	O
the	O
external	O
device	O
presented	O
the	O
lower	O
8-bits	O
(	O
or	O
9	O
in	O
some	O
cases	O
)	O
on	O
the	O
address	B-Architecture
bus	I-Architecture
,	O
and	O
the	O
complete	O
vector	O
address	O
was	O
then	O
constructed	O
from	O
the	O
three	O
values	O
.	O
</s>
<s>
In	O
the	O
early	O
1980s	O
,	O
the	O
Zilog	O
Z8000	O
CPU	O
was	O
popular	O
for	O
desktop-sized	O
Unix	B-Application
machines	O
.	O
</s>
<s>
These	O
low-cost	O
Unix	B-Application
systems	I-Application
allowed	O
small	O
businesses	O
to	O
run	O
a	O
true	O
multi-user	O
system	O
and	O
share	O
resources	O
(	O
disk	O
,	O
printers	O
)	O
before	O
networking	O
was	O
common	O
.	O
</s>
<s>
They	O
usually	O
had	O
only	O
RS-232	O
serial	B-Protocol
ports	I-Protocol
(	O
4	O
–	O
16	O
)	O
and	O
parallel	B-Device
printer	I-Device
ports	I-Device
instead	O
of	O
built-in	O
graphics	O
,	O
as	O
was	O
typical	O
for	O
servers	O
of	O
the	O
time	O
.	O
</s>
<s>
Z8000-based	O
computer	O
systems	O
included	O
Zilog	O
's	O
own	O
System	O
8000	O
series	O
,	O
as	O
well	O
as	O
other	O
manufacturers	O
:	O
</s>
<s>
1980	O
:	O
C8002	O
made	O
by	O
Onyx	O
Systems	O
used	O
the	O
Z8002	O
,	O
ran	O
Version	B-Operating_System
7	I-Operating_System
Unix	I-Operating_System
,	O
had	O
C	B-Algorithm
,	O
FORTRAN	O
77	O
and	O
COBOL	B-Application
compilers	O
available	O
.	O
</s>
<s>
It	O
had	O
eight	O
serial	B-Protocol
ports	I-Protocol
for	O
terminal	O
connections	O
,	O
1	O
QIC	O
tape	O
drive	O
and	O
cost	O
~	O
$25k	O
.	O
</s>
<s>
The	O
main	O
processor	O
offloaded	O
the	O
disk	O
,	O
tape	O
,	O
and	O
serial	O
I/O	O
operations	O
to	O
a	O
Z80	B-General_Concept
processor	O
on	O
a	O
second	O
board	O
.	O
</s>
<s>
1981	O
:	O
Zilog	O
Systems	O
Z-Lab	O
8000	O
Programmer	O
's	O
Development	O
System	O
,	O
available	O
as	O
a	O
Model	O
20	O
system	O
with	O
256KB	O
of	O
RAM	O
and	O
single	O
24MB	O
hard	B-Device
drive	I-Device
,	O
priced	O
at	O
$27	O
,	O
000	O
,	O
or	O
a	O
Model	O
30	O
system	O
with	O
512KB	O
of	O
RAM	O
and	O
dual	O
hard	B-Device
drives	I-Device
,	O
priced	O
at	O
$33	O
,	O
950	O
,	O
ran	O
the	O
Zeus	O
enhanced	O
version	O
of	O
Unix	B-Application
from	O
Zilog	O
.	O
</s>
<s>
Zilog	O
followed	O
up	O
with	O
the	O
Series	O
8000	O
,	O
a	O
multi-user	O
business	O
system	O
that	O
,	O
like	O
the	O
Z-Lab	O
8000	O
,	O
was	O
based	O
on	O
the	O
6MHz	O
Z8001A	O
with	O
three	O
Z8010A	O
memory	B-General_Concept
management	I-General_Concept
units	I-General_Concept
.	O
</s>
<s>
1981-1982	O
:	O
Plexus	O
Industries	O
 '	O
P/40	O
employed	O
an	O
Z8000-based	O
processor	O
along	O
with	O
a	O
number	O
of	O
peripheral	O
controllers	O
designed	O
to	O
maximise	O
data	O
transfer	O
performance	O
,	O
claiming	O
direct	O
memory	O
access	O
throughput	O
of	O
up	O
to	O
3MB	O
per	O
second	O
.	O
</s>
<s>
A	O
"	O
typical	O
eight-user	O
P/40	O
configuration	O
"	O
with	O
512KB	O
of	O
RAM	O
and	O
72MB	O
hard	B-Device
drive	I-Device
cost	O
$49	O
,	O
500	O
,	O
with	O
a	O
Unix	B-Application
licence	O
costing	O
$	O
5,000	O
extra	O
.	O
</s>
<s>
Plexus	O
followed	O
up	O
with	O
the	O
P/25	O
in	O
1982	O
,	O
claiming	O
similar	O
performance	O
to	O
a	O
PDP-11/70	O
system	O
.	O
</s>
<s>
A	O
later	O
Plexus	O
model	O
,	O
the	O
P/60	O
,	O
employed	O
the	O
Z8000	O
as	O
an	O
input/output	O
controller	O
but	O
introduced	O
the	O
Motorola	B-Device
68000	I-Device
as	O
the	O
main	O
CPU	O
.	O
</s>
<s>
The	O
Plexus	O
P/35	O
retained	O
this	O
general	O
architecture	O
.	O
</s>
<s>
1982	O
:	O
Olivetti	B-Device
M20	I-Device
,	O
a	O
non-IBM-compatible	O
PC	O
that	O
ran	O
Olivetti	O
PCOS	O
,	O
a	O
derivative	O
of	O
COSMOS	O
or	O
CP/M	O
8000	O
.	O
</s>
<s>
1982-1983	O
:	O
C5002A	O
,	O
C8002A	O
and	O
Sundance-16	O
from	O
Onyx	O
Systems	O
used	O
the	O
Z8001	O
and	O
ran	O
Unix	B-Operating_System
System	I-Operating_System
III	I-Operating_System
.	O
</s>
<s>
These	O
systems	O
ran	O
Unix	B-Operating_System
System	I-Operating_System
III	I-Operating_System
.	O
</s>
<s>
These	O
minicomputers	B-Architecture
from	O
Olivetti	O
all	O
ran	O
BCOS/COSMOS	O
.	O
</s>
<s>
1987	O
–	O
1989	O
:	O
the	O
East	O
German	O
EAW	O
(	O
Elektro-Apparate-Werke	O
)	O
produced	O
the	O
Workstation/Multiuser	O
System	O
P8000	O
based	O
on	O
the	O
East	O
German	O
U8000	B-Device
clone	O
of	O
the	O
Z8000	O
.	O
</s>
<s>
The	O
Zilog	O
S8000	O
computer	O
came	O
out	O
with	O
a	O
version	O
of	O
Unix	B-Application
called	O
ZEUS	O
(	O
Zilog	O
Enhanced	O
Unix	B-Application
System	I-Application
)	O
.	O
</s>
<s>
ZEUS	O
was	O
a	O
port	O
of	O
Unix	B-Operating_System
Version	I-Operating_System
7	I-Operating_System
and	O
included	O
what	O
were	O
referred	O
to	O
as	O
'	O
the	O
Berkeley	O
Enhancements	O
 '	O
.	O
</s>
<s>
ZEUS	O
included	O
a	O
version	O
of	O
COBOL	B-Application
called	O
RM/COBOL	B-Application
(	O
Ryan	O
McFarland	O
COBOL	B-Application
)	O
.	O
</s>
<s>
The	O
availability	O
of	O
RM/COBOL	B-Application
allowed	O
many	O
commercial	O
applications	O
to	O
be	O
quickly	O
ported	O
to	O
the	O
S8000	O
computer	O
although	O
this	O
did	O
not	O
help	O
its	O
long-term	O
success	O
.	O
</s>
<s>
The	O
Z8000	O
featured	O
in	O
Steve	O
Ciarcia	O
's	O
Trump	O
Card	O
project	O
for	O
his	O
Circuit	O
Cellar	O
column	O
in	O
Byte	O
magazine	O
,	O
providing	O
an	O
expansion	O
card	O
with	O
the	O
Z8001	O
processor	O
and	O
512KB	O
of	O
RAM	O
suitable	O
for	O
use	O
with	O
an	O
IBM-compatible	O
PC	O
.	O
</s>
<s>
Compilers	O
for	O
BASIC	O
and	O
C	B-Algorithm
were	O
supplied	O
with	O
the	O
board	O
,	O
along	O
with	O
an	O
assembler	B-Language
and	O
a	O
Z80	B-General_Concept
emulator	O
that	O
could	O
run	O
programs	O
written	O
for	O
CP/M	O
-80	O
.	O
</s>
<s>
It	O
was	O
envisaged	O
that	O
Unix	B-Application
would	O
also	O
be	O
made	O
available	O
for	O
the	O
Trump	O
Card	O
.	O
</s>
<s>
Despite	O
a	O
somewhat	O
positive	O
reception	O
as	O
"	O
a	O
reasonably	O
fast	O
supermicro	O
with	O
generally	O
good	O
performance	O
for	O
the	O
price	O
"	O
,	O
the	O
16-bit	B-Device
architectural	O
limitations	O
of	O
the	O
Z8000	O
,	O
with	O
segment	O
handling	O
required	O
to	O
access	O
more	O
than	O
64KB	O
in	O
a	O
process	O
,	O
led	O
to	O
questions	O
about	O
the	O
longevity	O
of	O
the	O
Series	O
8000	O
products	O
as	O
32-bit	O
processor	O
architectures	O
from	O
Motorola	O
and	O
National	O
Semiconductor	O
became	O
more	O
widely	O
adopted	O
.	O
</s>
<s>
Zilog	O
Systems	O
eventually	O
adopted	O
T	O
's	O
32-bit	O
WE32100	B-General_Concept
processor	O
,	O
introducing	O
it	O
in	O
a	O
new	O
product	O
,	O
the	O
System	O
8000/32	O
,	O
alongside	O
32-bit	O
upgrades	O
to	O
its	O
existing	O
System	O
8000	O
Series	O
2	O
models	O
.	O
</s>
<s>
This	O
enabled	O
the	O
introduction	O
of	O
Unix	B-Application
System	I-Application
V	O
on	O
Zilog	O
Systems	O
 '	O
products	O
.	O
</s>
<s>
The	O
adoption	O
by	O
Zilog	O
's	O
Systems	O
Division	O
of	O
the	O
WE32100	B-General_Concept
,	O
in	O
preference	O
to	O
the	O
continued	O
use	O
of	O
products	O
from	O
Zilog	O
's	O
Component	O
Division	O
,	O
was	O
driven	O
by	O
diverging	O
requirements	O
.	O
</s>
<s>
Zilog	O
sought	O
to	O
introduce	O
its	O
32-bit	O
successor	O
to	O
the	O
Z8000	O
,	O
the	O
Z80000	B-Device
,	O
to	O
build	O
on	O
successful	O
adoption	O
of	O
the	O
16-bit	B-Device
product	O
in	O
military	O
and	O
graphical	O
applications	O
,	O
whereas	O
its	O
Systems	O
Division	O
prioritised	O
Unix	B-Application
support	O
and	O
commercial	O
applications	O
.	O
</s>
<s>
The	O
conclusion	O
was	O
reached	O
to	O
adopt	O
the	O
WE32100	B-General_Concept
as	O
"	O
the	O
premier	O
UNIX	B-Application
chip	O
"	O
.	O
</s>
<s>
Zilog	O
subsequently	O
announced	O
an	O
agreement	O
to	O
manufacture	O
the	O
WE32100	B-General_Concept
chipset	O
for	O
a	O
five	O
year	O
period	O
,	O
being	O
the	O
first	O
alternative	O
source	O
of	O
these	O
products	O
.	O
</s>
<s>
There	O
was	O
a	O
Z8000	O
version	O
of	O
the	O
Xenix	B-Application
Operating	I-Application
System	I-Application
.	O
</s>
<s>
Namco	O
used	O
the	O
Z8000	O
series	O
in	O
its	O
Pole	B-Application
Position	I-Application
and	O
Pole	B-Application
Position	I-Application
II	I-Application
arcade	O
games	O
.	O
</s>
<s>
The	O
machines	O
used	O
two	O
Z8002	O
's	O
,	O
the	O
64KB	O
versions	O
of	O
the	O
Z8000	O
.	O
</s>
<s>
Federico	O
Faggin	O
,	O
then	O
CEO	O
of	O
Zilog	O
,	O
later	O
suggested	O
this	O
was	O
due	O
to	O
Zilog	O
's	O
financing	O
arrangement	O
with	O
Exxon	O
's	O
venture	O
capital	O
arm	O
,	O
Exxon	O
Enterprises	O
.	O
</s>
<s>
Comparing	O
assembly	B-Language
language	I-Language
versions	O
of	O
the	O
Byte	B-Language
Sieve	I-Language
,	O
one	O
sees	O
that	O
the	O
5.5MHzZ8000	O
'	O
s	B-Algorithm
1.1	O
seconds	O
is	O
impressive	O
when	O
compared	O
to	O
the	O
8-bit	O
designs	O
it	O
replaced	O
,	O
including	O
Zilog	O
's	O
4MHz	O
Z80	B-General_Concept
at	O
6.8	O
seconds	O
,	O
and	O
the	O
popular	O
1MHz	O
MOS	B-General_Concept
6502	I-General_Concept
at	O
13.9	O
.	O
</s>
<s>
Even	O
the	O
newer	O
1MHz	O
Motorola	B-Device
6809	I-Device
was	O
much	O
slower	O
,	O
at	O
5.1	O
seconds	O
.	O
</s>
<s>
It	O
also	O
fares	O
well	O
against	O
the	O
8MHz	O
Intel	B-General_Concept
8086	I-General_Concept
which	O
turned	O
in	O
a	O
time	O
of	O
1.9	O
seconds	O
,	O
or	O
the	O
less	O
expensive	O
5MHz	O
Intel	B-Device
8088	I-Device
at	O
4	O
seconds	O
.	O
</s>
<s>
While	O
the	O
Intel	O
processors	O
were	O
easily	O
outperformed	O
by	O
the	O
Z8001	O
,	O
they	O
were	O
packaged	O
in	O
40-pin	O
DIPs	B-Algorithm
,	O
which	O
made	O
them	O
less	O
expensive	O
to	O
implement	O
than	O
the	O
48-pin	O
Z8001	O
.	O
</s>
<s>
The	O
Z8002	O
also	O
used	O
a	O
40-pin	O
package	O
,	O
but	O
had	O
a	O
16-bit	B-Device
address	B-Architecture
bus	I-Architecture
that	O
could	O
only	O
access	O
64KB	O
of	O
RAM	O
,	O
whereas	O
the	O
Intel	O
processors	O
had	O
a	O
20-bit	O
bus	O
that	O
could	O
access	O
1	O
MB	O
of	O
RAM	O
.	O
</s>
<s>
Internally	O
,	O
the	O
23-bit	O
addresses	O
of	O
the	O
Z8000	O
were	O
also	O
more	O
complex	O
to	O
process	O
than	O
Intel	O
's	O
simpler	O
system	O
using	O
16-bit	B-Device
base	O
addresses	O
and	O
separate	O
segment	B-General_Concept
registers	I-General_Concept
.	O
</s>
<s>
The	O
16/32	O
-bit	O
8MHz	O
Motorola	B-Device
68000	I-Device
came	O
to	O
market	O
later	O
the	O
same	O
year	O
and	O
turns	O
in	O
a	O
time	O
of	O
0.49	O
seconds	O
on	O
the	O
same	O
Sieve	O
test	O
,	O
over	O
twice	O
as	O
fast	O
as	O
the	O
Z8000	O
.	O
</s>
<s>
Although	O
it	O
used	O
an	O
even	O
larger	O
64-pin	O
DIP	B-Algorithm
layout	O
,	O
for	O
those	O
willing	O
to	O
move	O
to	O
more	O
than	O
40-pins	O
this	O
was	O
a	O
small	O
price	O
to	O
pay	O
for	O
what	O
was	O
by	O
far	O
the	O
fastest	O
processor	O
of	O
its	O
era	O
.	O
</s>
<s>
Its	O
32-bit	O
instructions	O
and	O
registers	B-General_Concept
,	O
combined	O
with	O
a	O
24-bit	O
address	B-Architecture
bus	I-Architecture
with	O
flat	O
16MB	O
addressing	O
,	O
also	O
made	O
it	O
much	O
more	O
attractive	O
to	O
designers	O
,	O
something	O
Faggin	O
admits	O
to	O
.	O
</s>
<s>
This	O
was	O
due	O
to	O
its	O
complex	O
instruction	O
decoder	O
,	O
which	O
,	O
unlike	O
most	O
processors	O
of	O
the	O
era	O
,	O
did	O
not	O
use	O
microcode	B-Device
and	O
was	O
dependent	O
on	O
logic	O
implemented	O
directly	O
in	O
the	O
CPU	O
.	O
</s>
<s>
This	O
allowed	O
the	O
design	O
to	O
eliminate	O
the	O
microcode	B-Device
storage	O
and	O
the	O
associated	O
decoding	O
logic	O
,	O
which	O
reduced	O
the	O
transistor	O
count	O
to	O
17,500	O
.	O
</s>
<s>
In	O
contrast	O
,	O
the	O
contemporary	O
Intel	B-Device
8088	I-Device
used	O
29,000	O
transistors	O
,	O
while	O
the	O
Motorola	B-Device
68000	I-Device
of	O
a	O
few	O
months	O
later	O
used	O
68,000	O
.	O
</s>
<s>
Such	O
virtual	O
processors	O
were	O
provided	O
through	O
the	O
augmentation	O
of	O
the	O
Z8001	O
with	O
an	O
"	O
intelligent	O
memory	O
device	O
"	O
,	O
this	O
providing	O
memory	O
management	O
and	O
context	B-Operating_System
switching	I-Operating_System
facilities	O
,	O
with	O
additional	O
capability-related	O
instructions	O
being	O
supported	O
through	O
emulation	O
.	O
</s>
