MITS altair 680b User manual

altair 68Ob
II.
MAIN PC
BOARD
ASSEMBLY
ICSocketandIC Installation
Capac'i
tor Instal
Iation
ResistorInstallation
Transi
stor Instal
Iation
Diode
andCrystal
Installation
Voltage
Regulator
Installation
BridgeRect
j
fier Instal
I
at'ion
ConnectorInstal
I
ation
Input/0utput
Confi
gurations
Jumper
Wire
Connections
Paper
TapeReader
Control
M0S
IC Installation

IC SocketInstal
I
ation
Thereare 15
onthe 6B0b
Instal
I the
instructi
ons
The
s'ize
for
IC
sockets
to beinstalled
t,lai
n PC
Board.
ICsockets
according
to the
qjven
on
page
7, sectionB.
each
socketis listed below.
The
ICs
that areto be'installed'into
these
sockets
arealI stati
c-sens'it'ive
I40S
ICs. (see
page
6
)
Install onl.v
thesockets
at this t'ime.
D0NOTinstall the ICsin the
sockets
unt'il theMain PC
Board
hasbeen
com-
pletely
assembled.
15
IC Desi
qnat'ion
( ) c,
D,
Eo
F,
G,
H,
J, K,
and
Z
O T, U,
V, l^J,
and
JJ
( ) ilN
16
pin
24 pin
40
pin

iC Installation
There
are3l ICs
to be
jnstalled
(with-
out sockets)
ontotire
6B0b
Majn
PC
Board.
Instal
I these
ICs
accordi
ng
to the 'in-
structionson
page
7, section
A. The
correct part numbersfor the ICs are
listedbelow.
Part I'lumber
il A, B,
X,HH,MM,VV,
()
()
()
()
()
()
()
()
()
()
()
and 7Z
L (Baudot only)*
M
ll and P
R,S, CC,
and
PP
Y
AA,KK,LL,andUU
BB
DD,
EE,and
FF
GGandSS
TT
RR,I,l'',l,
XX,
and
YY
741S04
74L574
74LSl
0
74LS0l
4050**
741S00
741S30
4449**
74L520
74L502
741S73
74367
(or BT97)
*i'l0TE:Install ICL 0iiLYif a
Baudottermi
naFs to be
i
nterfaced
to the 680b.
**Stat'i
c-Sensi
ti ve MOSICs.
See
page
6 beforeinstalling.
l6

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11

Capaci
tor Instal Iation
There
are 6 electrolvtic capacitors
(cl,
c2,
c3,c4,
c5,andclb),I
tantalum
capacitor
(C6),
and43cer-
amic
disk
capacitors
(C7
through
C14
and
C50
throuqhCB4)
to beinstalled
onthe MainPC
Board. Install the
electrolytic capacitorsand
the tan-
talum
capacitoraccording
to the
instructions
given
on
page
9, Sec-
tion A. Install theceramicdisk
capacitors
accordinq
to the instruc-
tions
on
page
9, Section
B.
The
valuesfor all 50capacitorsare
Iisted
below.
i
tor Val ues
()ct,c2,
()c4,c5
( ) co
()c7,cB
( ) cg,cto
()cil
LJ 35uf
.l00
uf
luf
56
pf
430
.001
50
pf
.0.|
uf
.l uf
3300
uf
pf
uf
( ) ct2
( ) cr3
*( ) Cl4,C50
throuqh
CB4
( )
crs
*NOTE:Save
the
Ieads
cl
through
extra capaci
tor
ippedfrom
C50
CB4for later use.
t8

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r9

Res
is
tor Ins ta
IIation
Instal
I the fol I
owinq
on the l'lainPCBoard.
structions listed on
37
resistors
Use
thein-
N0TE:
Al'l of the resistors
onthe
Main
PC
Board
are either 1/4
watt or 1/2watt, except
R21,
which
is a 2-watt
res.istor.
page
B.
Resistor
Values
and
Color
Codes
I
) Rl throughR9,Rl5,R30
) Rl0,
Rll, Rl3,Rl7,
RIB
) Rr2
) Rt4
) Rt6
) Rl9,R20
) R2r
) R22
) R23,
R2B
) R24,
R25,R26,R27,
R3l,R32
) Rze
yel
Iow,
violet
, red
brown,
black,
orange
orange,
orange,orange
orange,
oranqe,brown
brown,black,
blue
orange,
orange,
red
(2
watt), brown,
gFeer,
black
brown,
b1ack,
red
ye'l
1ow,
violet, b1 ack
yel
Iow,
v'io1et,
brown
brown,b1
ack, brown
4.7K
ohm,
l0K
ohm,
33Kohm,
330
ohm,
10M
ohm,
3.3K
ohm,
15ohm
1K
ohm,
47
ohm,
470ohm,
100
ohm,
Res'istorPack
Instal
I
ation
After
installing
a1l
37resistors,
the 4 resistor packs
(RPl
through
RP4)
mustbe
installed. There-
sistors within these
packs
eachhave
a value
of 4.7Kohms.Each
pack
has
a smalldot printed
at one
end.
Thisdot must
correspondwith the
dot printeE-on
the PCBoard. Use
thefollowing
instructions
to in-
stall each
resistor
pack.
l. Install theresistor
pack
at
a perpendicular
angle
to the
silk-screened
side
of the
board. Make
surethe dot on
the resi stor pack i
s a1i
gned
with the dot printed
onthe
PC
Board.
Tape
the resistor pack
in place
andturn the boardover. Be-
fore solderinq,
check
that the
resistor
pack
is still perpen-
dicular to the board. Carefully
solder
each
pin of theresistor
pack
to the foil patternon the
backof the board.+
Turn
the boardoveraqainand
remove
the tape.
( ) RPI
through
RP4are 4.7Kohm
resistor packs
2.
?
*N0TE:
The
foil pattern
onthe
solder
mask.
Thesoldermasks
back
of the boardis
helps
prevent
solderpartially covered
by a
bri
dgesacross
I
ands.

Special lnsert Page
RESISTOR
PACK
SUBSTITUTIOi'IS
ALTAIR
6BObI'IAIN
PCBOARD
Due
to supplyshortages,
your
6B0b
kit hasbeen
shipped
to you
wjthout
thefour4.7K
ohm
Resistor
Packs
(npt-np+)
calledfor on page
20
of theAssemblyManual.
Nine
4.7K
ohm,
1/4
wattres'istors
have
been
substituted
for each
pack. These
substitute
resistors
mustbe
installed
according
to thedjrections
outljned
below.
Substi
tute Resi stors
, RPI
-RP4
Instal
IationProcedure
i"lote
that each res'istor
pack
designation
on
the
silk screenhas
l0 holes. The
left-mostholeis marked
on
thesilk
screenwith a dot.
Beginning
with
the
box
labeled
RP1,
in-
sert one4.7K
ohm,1/4watt (ye1'low-
violet-red
) resi
stor vertica1
'ly into the
right-most
hole
in the box. Bend
the
top lead at two
rjght angles,asshown
jn the diagram,
sothat the endof the
free lead
maybe
insertedinto the hole
markedwith a dot. Solder
the two
in-
sertedleads to the foil patternonthe
back
of the board.
Insert the remai
n'ingei
ght 4.7Kohm,
l/4 watt resistors
vertically into the
remainingeight
ho1es.Soldereach
of
the top'leads
to the common horizontal
leadof the fjrst resistor. It may be
helpful to bend
the top leads
against
the horizontal
leadfor better contact
beforeso1dering.
Solderthe inserted leads
of the
eight
resistors
to the foil pattern on
the
back
of the board. Clin all excess
leadsfromthe torr
and
bottomof the
res'istors.
Repeatthis procedure
for RPZ,RP3 and
RP4.
J.
t.
2
A
q
Resistor Instal
I
ati
on Completed
Resistor
Assembly

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TransistorInstal
Iation
Therc
arefive transistorsto be
instal
I
ed
onthe l4ai n PCBoard.
Q2,
03,
Q4,
and
Q5
should
be
in-
staliedfirst. ToinstalI these
4 trans'istors
, fo1I
owthe 'i
nstruc-
t'ions
given
on
page
'10.
MAKE
SURE
YOUIi'ISTALLTHE
EMITTERLEADINTO
THEIIOLE
LABELLED
''E"
ONTHE
B0ARD"
SeetheTransistorIden-
ti fi cati
onChart onpage
11 for
'i
denti
f i
cat'ionof the emitter
Iead.
install transistor
Q1
next. Ql is
a TIP-30
power
transistor
that will
beinstalI
ed
wi
th a smalI heat
s'ink.
Use
the instructionsand
diagram
below
to install 0.|.
WARNING:
TheTiP-30is verysimilar
in appearanceto theMC7B05
voltage
regulator
(VRl). When
installing
Ql, make
sure
you
have
selected
the
part labeledTIP-30.
t" Set
theTIP-30
'in
place
onthe
board
andalign the
mount'ing
holes. Use
a pencil
to mark the
point oneach
of the threeleads
where
they'lineup
with the'ir
nespective
holesonthe board.
Useneedle-nose
pliers to bend
eachof the threeleads
at a
right anqleonthe points
where
you
madethe pencil
marks.
NOTE:
Use
heat-sink
grease
when
in-
stal
I
ing this component.
App1.y
the
grease
to all surfaces
which
come
in
contact
with each
other.
3. Referring
to the drawing,set
thetransistor
andheatsink in
place
on
thesilk-screened
side
of the board. Securethem
to
the board
using
a #6-32 nut.
Hold
the
transistorin place
as
youtighten the nut to keepfrom
twistinq
the leads. Zz
4. Turn the board
overand
solder
the three Ieadsto the fo'il Pat-
tern onthe back
sideof the
board. Besure
not to leave
anY
solder
bridges.
5. Clipoff any
excess
leadlengths.
Part
numbers
for the five transis-
tors are given
below.
TransistorPart
Numbers
()at
( ) Q2,
( ) Q4,
Q3
Q5
TIP-30
ccs-4438
2N-2907
T- *6-32
rl+"
TIP-30
2. SMALL
HEAT
SINK
*e-SZ -e)

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D_rsdg_U5lg
l_l_q!io1
There
arefive diodes
(Dl, D2,
D3,
D4,
and
D5)
to be
installed
on
the
Main
PC
Board.
Toinstall these
diodes,
follow
the instructions
qi-
ven
on
page
10.
Part numbers
for the five diodes
are
Ii
sted
bel
ow.
Diode
Part Numbers
Qry:_td*Ipl q
t
_]g!ip-l
There
are two
crystalsto bein-
stalled onthe 680
Main
PC
Board.
XTAL
I is a 2.4576
MHz
crysta'l
and
XTAL
2 is a 2.000
MHz
crystal.
Follow
the instructions
below
for
installation
of each
crystal.
l. Use
needle
nose
pliers to
straighten
the leads
on
the
crysta'l
.
2. Insertthe leads
into the cor-
rect holes
unt'il the crystal
case
stands
1/8" off the sur-
face
of the board. (Do
not
allow
themetal
crystal case
to comeinto contact
with
anyof the
lands
on
the
board.)
Holdfng
the
crystal
in place,
turn the board
over
and
bend
the leads
slightly outward.
Sol
der the I
eads
to the foi
I
pattern
and
clip off any
ex-
cess
lead
lengths.
Ir
) Dl, D2,
D3,
D5
)D4
I
N4004
,l0.0
volt 3.
4
( ) xrAL
1 2.4516
vHz
( ) xrnl z ?.
oooMHz
24

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25

Voltaqe
Requlator
Installation
Thereis one
7805
5-volt regulator
(VRl)
to be installed
onthe
6B0b
MainPCBoard.
Usethe followjng
instructjonsand
the
d
jagram
bel
ow
to 'instal
I the voltage
regulator.
'1. Set
the 7805
in place
on
the board
and
al"ign
themountjng
ho1es.
Use
a pencilto markthe point on
each
of the three Ieadswhere
they 1ine
upwith their respectjve
holeson
the board.
2. Useneedle-nose
pliers to bend
each
of the threeleadsat a right angle
onthe pointswhere
you
madethe
penci
I marks.
fl
I UOf
r: Use heat-s
j
nkgrease when
'instal
- |
I Tlnct
this comJronent.
Applythe grease I
I to a1l surfaces
wh'ichcome
in contact I
I with eachother. I
r.l
HEAT
SINK
Referri
nq to the drawinq, set the
requlator andheat s'ink
'in pl
ace
on
the silk-screenedside of the board.
Securethemto the board
usi
nq a
#6-32 nut. llol
d the requlator in
place as you tighten the nut ls koon
fromtwisti ng the Ieads.
Turnthe board over andsolder the
three leads to the foil pattern on
the back side of the board. Besure
not to leaveanysolder
bridges.
Clip off any
excesslead lengths.
( ) VRI
is part number
7805.
?
A.
6
f-s6-32r l+"
MC7805
'll
tl
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tl
tl
ll
26 *e-sZ-----.-..*@
tr

Bridge
Rectjfjsr Installation
Thereis one
VJ04B
bridge
rectifier
(BRl)
to beinstalled
onthe
680Main
PC
Board.
It will be
installed
with
oneof thelarge
heat
sinksover
it.
Examjnethe diagrams
shown
belowanduse
the
followinginstructions
to install BRl.
l'lOTE:Useheat
sink grease
wheninstal-
ffig this component.
Applythe grease
to the bridgerectifier andthe heatsink
where
they are in contact
with each
other.
l. 0rientthe
bridgerectifier andthe
heatsinkas
shown
in theillustra-
tion below. Note
that themounting
holein the
heat
sink is not center-
edbut is closer
to one
end. Make
sure
you
orient the "+" leadof the
rectifier under
thewider
endof
theheat
sink, as
shown.
Orientthe
heatsink
andrectifier
assemblycorrectlyoverthe board,
asshownin thenextillustration.
When
you
havethe proper alignment,
thewiderend
of the heatsinkwill
be
pointing
towardsthe right side
of the PCboard,and the "+" lead
wiII be
goinq
jnto the
"+"
hole.
Putthe four leadsfrom the bridge
rectifier throughthe proper
holes
onthe PC
board
untjI the prongs
of
the heat
sink rest onthe board.
If necessary,
bend
the prongs of
theheat
sinkoutwardsliqhtly so
that theydonot contactany
1
ands
when
mounted
to the board.
Holding
the
heat
sink
jn p1ace,
turn the boardover
and
bend
the
four leads
s1ightly outward.
Solder
the leads
to the foil pattern onthe
backof the board
andcl'ipoff any
excess
lead
lengths.
?
A,
E
?. Attachthe
recti
fi er,
screwand
a
.l{. .,
- 6-32 Xt/2
SCREW
HEAT
SINK
BRIDGE
RECTIFIER
heat
sink
to the
bridge
usinq
a #6-32
x l/2 inch
#6
hexnut.
27
WARNING!
It is absolutely
essential
that-ttre
bridgerectifier beoriented
correctly, so that the "+" leadcorre-
spondswith the "+" holeonthe PCboard.
Failure
to orient
the
bridge
rectifier
properlywill result in permanent
dam-
ageto your unit.
*e nExNUT

5-Prr{
UALE,
COIINECTOR
{*e
))<:;""
5-pi
n
male
connector
(lz1
ConnectorInstalI
ati
on
Therearethree
sjlk-screendesignations
for connectors onthe 6B0b
MainPC
Board:
Jl, J2andJ3.
JI
Jl is not 'included
with
your
kit and
is
not to beinstalled a'L
this time" The
desi
gnat'ion
Jl j s for a 100-pin edge
connector
that wiII be used
for future
memory
and
I/0 expansion.The
connec-
tor itse'lf i s incl uded
with the purchase
of anexpander card.
J2
J2 js a 5-pinmalemolexconnector.
In-
stall J2 ontothe Ma'inPCBoardaccord'inq
to the following
instructions.
l. Cutthe
bent
pins
off l/8" from
tfre
Uody
of tEe
Tonnector,
as
shown.
This
modification'is
necessary
before
the connector
will fit proper'ly
onthe PCboard.
N0TE:Disregard
this step
jf the
bent
pins
have
been
pre-cut
at the factory.
2. Orient the connector
J2 as shown
below,
with the closed
side
facinq the le_ft E!@Ti&-of the
6oeFa:
Tnsert tE-VE"Tins lnto
TFETive holeson the silk screened
s'ideof the board.
3. Hold'inq the connector i
n place,
turn the board over andsolder
the f ive p"ins to the fojl pattern
on the back s'ide
of the board.
'l?
UJ
J3 'isa 5-pin mini
ature
mal
e molex con-
nector. Instal I J3 ontothe Ma'in
PC
Board
accordingto thefollowing
'instruc-
t"ions
.
l. Insert
theshort
pins
into the five
holes on thilTlk-ffieened side of
the
MainPC
Board,
asshown
below.
2. Holdjngthe connector
in p1ace,
turn theboard overandsolder
the fi ve pi
ns to the foi
1 pattern
onthe
back
side
of the
board.
5-pin mj
n'iature
male
connector
(J3)
and
J3 Installati
onl
_l

ttu111][lrt
u
!Er-L-
_qu-t-j1s1g!gr:-
Irrt,he
upper
Ieft-handcorncr
of tlte
Mai
n [)C
[Joard
, a ltort
ionof
thefoil pattern
has
beenboxedoff andlabeled
"l/0."
Thecomponents
in this boxmay
be configured in one of three
different ways,depending
onthe interfacelevel desired.
A. ASR33/KSR33
Teletype
Interface
(20
macurrent
loop)
B. Standard
RS-232Interface
C. Baudot
Interface
The
component
configurat'ion
for eachof the three 'interface
levels
is diagrammed
below. The correct part numbers
and
values
appear
onthe
d'iagrams.
Install thesecomponents
ontothe "I/0" section
of theMain
PC
Boardaccord'ing
to the jnterface
level you
are
planning
to use.
A. ASR33/l(SR33
Teletype
Interface
(20
macurrent
loop) R20|
35O
-'lczoo
Itf -
0200
rN9ta
' Dzo
l'to''
R2O3 rNet.
R204
470 rt
TTY
-:-
I
R202
IK
Q
200
2N?
9A7
220 ^

B. Standard
RS-232
Interface
RS232
_:-
o300
?N29oz
C. Baudot
Interface*
*,Th'is
component
confiquration
alone
does
not provide
a Biudot level
interface
for the 680b. It is
also
necessary
to include
a level
converting
andisolation
circuit
(either
a read
relay
or anoptical
'isolation
circujt
wjll suffice).
A suggested
j
sol
ationci
rcui
t 'is
shown
in the Altair 6B0b
0perator's
Manual.
IAUDOT
R
401
?20JL
.,UMPER
Q
400
2r{2907 D402
R
405
l8 o .rr

Jumper
inlj
re Co!.llecti
ons
0n the 6B0b
MainPC
Board,the followjnq three areas
require jumper
wire connect'ions
:
A. Baud
RateGenerator
(pads
0-3, to the left of IC 7)
B. RAM Starting Acldress
(pads
l-6 and l0-T5, between
ICsAA& BB)
C. Hardware
Programmable
Bits (pads 1-5, to the left of IC WW)
Usethe capacjtor
leadssaved
earlier to make
the jumper
connections.
Cut the leads to s'izeand
jnsert the ends
into the proper
holes fromthe
sjlk screened
side of the board. Solderthe endsto the fojl pattern.
lvlake
sure the wire'is raised f
/4" or so above the boardso that none of
the lands underneath
are shorted.
A. BAUDRATE
GENERATOR
l4ovjnqto the left front
IC Z there is: l) a column
of four
holeslabeied
0 throuqh
3; 2) a columnof four holes (not labeled)
representi
ng the qround
(L0l^J)
pl
ane; 3) a col
umn
of four holes
(not labeled)representing
the +5 volt (HIGH)plane.
The
baudrate for the 6B0b
computeris user selectable
accord-
ing to the jumper
connect'ions
p1aced
acrossthese
holes. The con-
figurations of the jumper
wires for the variousbaudrates are
I
'i
sted in the chart on the next paqe
.
31