<s>
N8VEM	B-Device
was	O
a	O
homebrew	O
computing	O
project	O
.	O
</s>
<s>
N8VEM	B-Device
builders	O
made	O
their	O
own	O
homebrew	O
computer	O
systems	O
for	O
themselves	O
and	O
shared	O
their	O
experiences	O
with	O
other	O
homebrew	O
computer	O
hobbyists	O
.	O
</s>
<s>
N8VEM	B-Device
homebrew	O
computer	O
components	O
are	O
made	O
in	O
the	O
style	O
of	O
vintage	O
computers	O
of	O
the	O
mid	O
to	O
late	O
1970s	O
and	O
early	O
1980s	O
using	O
a	O
mix	O
of	O
classic	O
and	O
modern	O
technologies	O
.	O
</s>
<s>
In	O
November	O
2015	O
the	O
N8VEM	B-Device
project	O
was	O
ended	O
by	O
its	O
creator	O
Andrew	O
Lynch	O
and	O
the	O
community	O
reconvened	O
under	O
the	O
new	O
name	O
of	O
Retrobrew	O
Computers	O
.	O
</s>
<s>
There	O
are	O
several	O
N8VEM	B-Device
designs	O
starting	O
with	O
a	O
single-board	B-Device
computer	I-Device
carrying	O
a	O
Z80	B-General_Concept
microprocessor	I-General_Concept
designed	O
to	O
run	O
CP/M	B-Application
and	O
similar	O
operating	O
systems	O
.	O
</s>
<s>
Contrasted	O
with	O
the	O
P112	B-Device
,	O
which	O
has	O
some	O
surface-mount	O
components	O
,	O
the	O
N8VEM	B-Device
SBC	O
uses	O
only	O
through-hole	O
components	O
,	O
consistent	O
with	O
the	O
design	O
philosophy	O
that	O
building	O
should	O
be	O
within	O
the	O
skills	O
and	O
resources	O
of	O
non-professional	O
hobbyists	O
.	O
</s>
<s>
The	O
project	O
has	O
also	O
developed	O
boards	O
for	O
other	O
processors	O
including	O
Z180	B-Device
,	O
Intel	B-Device
80188	I-Device
,	O
MOS	B-General_Concept
6502	I-General_Concept
,	O
Motorola	B-Device
6809	I-Device
,	O
68000	B-Device
and	O
68030	B-Device
.	O
</s>
<s>
The	O
N8VEM	B-Device
boards	O
are	O
designed	O
with	O
the	O
free	O
KiCad	B-Language
Electronic	O
design	O
automation	O
(	O
EDA	O
)	O
toolset	O
.	O
</s>
<s>
Software	O
is	O
developed	O
in	O
Z80/8085	O
assembly	B-Language
language	I-Language
using	O
the	O
MS-DOS	B-Application
Telemark	O
Cross	O
Assembler	B-Language
program	I-Language
(	O
TASM	O
)	O
,	O
as	O
well	O
as	O
the	O
open	O
source	O
Small	B-Application
Device	I-Application
C	I-Application
Compiler	I-Application
.	O
</s>
<s>
The	O
printed	O
circuit	O
board	O
design	O
is	O
supplemented	O
using	O
component	O
libraries	O
available	O
at	O
KiCad	B-Language
Libraries	O
,	O
specifically	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
CPU	B-Device
and	O
Intel	B-Device
8255	I-Device
PPI	O
chips	O
.	O
</s>
<s>
There	O
are	O
numerous	O
N8VEM	B-Device
components	O
available	O
including	O
ECB	B-Architecture
and	O
S-100	B-Architecture
backplane	O
boards	O
,	O
allow	O
processor	O
and	O
expansion	O
boards	O
to	O
be	O
connected	O
.	O
</s>
<s>
In	O
response	O
to	O
interest	O
from	O
members	O
,	O
the	O
N8VEM	B-Device
homebrew	O
computing	O
project	O
has	O
collaborated	O
in	O
developing	O
a	O
range	O
of	O
boards	O
for	O
the	O
S-100	B-Architecture
bus	I-Architecture
.	O
</s>
<s>
These	O
can	O
be	O
used	O
to	O
build	O
new	O
systems	O
from	O
scratch	O
on	O
that	O
historic	O
industry	O
standard	O
platform	O
,	O
or	O
to	O
restore	O
and	O
enhance	O
vintage	O
S-100	B-Architecture
systems	O
preserved	O
from	O
the	O
1970s	O
and	O
1980s	O
.	O
</s>
<s>
Most	O
of	O
the	O
S-100	B-Architecture
board	O
initial	O
design	O
work	O
has	O
been	O
contributed	O
by	O
John	O
Monahan	O
of	O
s100computers.com,	O
with	O
board	O
layout	O
,	O
prototyping	O
and	O
testing	O
contributed	O
by	O
Andrew	O
Lynch	O
and	O
other	O
N8VEM	B-Device
supporters	O
.	O
</s>
<s>
Some	O
of	O
these	O
S-100	B-Architecture
boards	O
provide	O
enhanced	O
capabilities	O
beyond	O
what	O
was	O
available	O
on	O
original	O
S-100	B-Architecture
machines	O
,	O
some	O
are	O
replacements	O
for	O
historic	O
S-100	B-Architecture
boards	O
,	O
and	O
other	O
board	O
projects	O
aim	O
to	O
apply	O
the	O
convenient	O
bus	O
architecture	O
to	O
processor	O
families	O
beyond	O
the	O
8080/Z80	O
CPUs	B-Device
for	O
which	O
the	O
bus	O
standard	O
was	O
originally	O
designed	O
:	O
notably	O
6502	B-General_Concept
,	O
68000	B-Device
,	O
and	O
later	O
Intel	O
processor	O
types	O
.	O
</s>
<s>
N8VEM	B-Device
is	O
notable	O
for	O
being	O
the	O
largest	O
and	O
most	O
active	O
homebrew	O
computing	O
community	O
in	O
existence	O
today	O
.	O
</s>
<s>
Support	O
is	O
purely	O
on	O
a	O
volunteer	O
basis	O
through	O
a	O
Google	B-Application
Group	I-Application
and	O
Wiki	B-Protocol
.	O
</s>
<s>
Software	O
is	O
open	O
source	O
and	O
freely	O
available	O
for	O
download	O
from	O
the	O
Wiki	B-Protocol
.	O
</s>
<s>
In	O
addition	O
,	O
notable	O
freeware	O
system	O
emulator	O
SIMH	B-Application
simulates	O
the	O
N8VEM	B-Device
SBC	O
(	O
along	O
with	O
many	O
other	O
architectures	O
)	O
,	O
providing	O
a	O
virtualised	O
development	O
environment	O
that	O
has	O
the	O
speed	O
and	O
flexibility	O
of	O
modern	O
hardware	O
.	O
</s>
<s>
Completed	O
N8VEM	B-Device
hardware	O
and	O
software	O
has	O
frequently	O
been	O
displayed	O
at	O
Vintage	O
Computer	O
Festivals	O
.	O
</s>
<s>
ECB	B-Architecture
Bus	O
:	O
</s>
<s>
S-100	B-Architecture
bus	I-Architecture
:	O
</s>
<s>
6502/6809	O
ECB	B-Architecture
+	O
carrier	O
boards	O
for	O
other	O
cpu	B-Device
's	O
(	O
?	O
)	O
</s>
<s>
SBC6120-RBC	O
:	O
A	O
new	O
edition	O
of	O
the	O
Spare	O
Time	O
Gizmos	O
updated	O
to	O
use	O
easily	O
available	O
RAM	O
and	O
EEPROM	O
components	O
,	O
only	O
two	O
PCB	O
layers	O
,	O
and	O
KiCAD	B-Language
.	O
</s>
<s>
There	O
is	O
an	O
active	O
community	O
development	O
forum	O
(	O
N8VEM	B-Device
Google	O
Discussion	O
Group	O
)	O
from	O
which	O
additional	O
board	O
designs	O
have	O
been	O
developed	O
.	O
</s>
<s>
RomWBW	O
is	O
a	O
popular	O
system	O
software	O
distribution	O
written	O
to	O
execute	O
on	O
N8VEM	B-Device
hardware	O
.	O
</s>
<s>
The	O
N8VEM	B-Device
family	O
of	O
hardware	O
are	O
primarily	O
Z80	B-General_Concept
based	O
microprocessor	O
single	B-Device
board	I-Device
computers	I-Device
,	O
as	O
well	O
as	O
miscellaneous	O
boards	O
which	O
may	O
be	O
combined	O
and	O
placed	O
in	O
an	O
ECB-like	O
bus	O
,	O
enabling	O
the	O
builder	O
to	O
create	O
a	O
custom	O
computer	O
system	O
.	O
</s>
<s>
The	O
majority	O
of	O
the	O
systems	O
are	O
Z80	B-General_Concept
based	O
and	O
use	O
the	O
CP/M	B-Application
-80	I-Application
operating	O
system	O
that	O
was	O
developed	O
in	O
the	O
late	O
1970s	O
by	O
Digital	O
Research	O
,	O
Inc	O
.	O
</s>
<s>
The	O
RomWBW	O
system	O
software	O
is	O
highly	O
configurable	O
and	O
supports	O
all	O
of	O
the	O
Z80	B-General_Concept
based	O
systems	O
constructed	O
with	O
N8VEM	B-Device
components	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
fully	O
implemented	O
operating	O
system	O
with	O
its	O
BIOS	O
(	O
customized	O
for	O
the	O
N8VEM	B-Device
hardware	O
)	O
,	O
there	O
are	O
several	O
dozen	O
utility	O
programs	O
that	O
configure	O
and	O
verify	O
the	O
proper	O
operation	O
of	O
system	O
components	O
such	O
as	O
persistent	O
storage	O
in	O
the	O
form	O
of	O
IDE	B-Protocol
Hard	I-Protocol
Drives	I-Protocol
,	O
Compact	O
Flash	O
,	O
and	O
Secure	B-Device
Digital	I-Device
chips	O
.	O
</s>
<s>
The	O
CP/M	B-Application
-80	I-Application
BIOS	O
is	O
written	O
in	O
assembly	B-Language
language	I-Language
and	O
is	O
built	O
using	O
the	O
TASM	O
assembler	B-Language
.	O
</s>
<s>
Utility	O
programs	O
are	O
written	O
in	O
a	O
variety	O
of	O
languages	O
including	O
assembler	B-Language
,	O
Digital	O
Research	O
RMAC	O
,	O
Aztec	O
C	O
,	O
and	O
Digital	O
Research	O
PLI	O
.	O
</s>
<s>
These	O
natively	O
hosted	O
programming	O
languages	O
,	O
and	O
tools	O
such	O
as	O
WordStar	O
(	O
a	O
popular	O
editor	O
of	O
the	O
time	O
)	O
,	O
execute	O
under	O
the	O
CP/M	B-Application
operating	I-Application
system	I-Application
and	O
read	O
source	O
files	O
stored	O
on	O
memory	O
disk	O
or	O
persistent	O
media	O
such	O
as	O
IDE	O
devices	O
or	O
Compact	O
Flash	O
and	O
Secure	B-Device
Digital	I-Device
devices	O
through	O
the	O
use	O
of	O
an	O
external	O
adapter	O
.	O
</s>
<s>
The	O
version	O
1.x	O
distributions	O
of	O
the	O
system	O
software	O
have	O
been	O
written	O
in	O
a	O
very	O
standard	O
CP/M	B-Application
-80	I-Application
way	O
and	O
over	O
the	O
course	O
of	O
a	O
half	O
dozen	O
releases	O
has	O
reached	O
a	O
highly	O
stable	O
state	O
supporting	O
the	O
most	O
commonly	O
built	O
configurations	O
in	O
use	O
.	O
</s>
<s>
in	O
many	O
ways	O
similar	O
to	O
the	O
CP/M	B-Application
-80	I-Application
Plus	O
family	O
of	O
operating	O
systems	O
which	O
also	O
took	O
advantage	O
of	O
memory	O
paging	O
.	O
</s>
<s>
It	O
has	O
the	O
advantage	O
that	O
a	O
single	O
ROM	O
image	O
can	O
run	O
on	O
all	O
Z80	B-General_Concept
and	O
Z180	B-Device
systems	O
.	O
</s>
<s>
An	O
alternative	O
CP/M	B-Application
implementation	O
,	O
UNA	O
CP/M	B-Application
,	O
takes	O
advantage	O
of	O
UNA	O
BIOS	O
disk	O
and	O
device	O
drivers	O
.	O
</s>
