Heathkit H9 User manual

n$ffiuAt
for the
VIDEO
TERMINAL
Model
H9
oPERATION 595-2017-03
,l
I
HEATH
COMPANY
. BENTONHARBOR,
MICHIGAN

HEATH
COMPANYPHONEDIRECTORY
.
Thefollowingtelephone
numbers
aredirect
lines
tothedepartmentslisted:
Kitordersanddeliveryinformation ......[phone]
Credit. .. ... .(616)
982-3561
ReplacementParts
". .. (616)
982-3571
Technical
AssrstancePhoneNumbers
8:00A.M.to 12P.M.
and 1:00P.M.to 4:30P.M., EST,Weekdays
Only
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andElectronicOrgans ..... (616)
982-3310
AmateurRadio. ... .. . (616)
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TestEquipment,
WeatherInstruments
and
HomeClocks ....... (616)
982-3315
Television .... (616)
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Aircraft,Marine,
Security.
Scanners,
Automotive,
Appliancesand
General
Products ."... (616)
982-3496
Computers ... (616)
982-3309
YOURHEATHKIT 90 DAY LIMITED WARRANTY
If you are not satisfied with our seroice - warranty or otherwise - or with our products, mite directly to our Director of Customer
Services,Heath Company, Benton Hubor, Michigan 49022. He will make certain your problems receive immediate, personal
attention.
Our attorney, who happens to be quite akitbuilder himself, insists that we desctibe our warranty using all the necessary legal €
phrases in order to comply with the new wananty regulations. Fine. Here they are: :iC)
For aperiod of ninety (90) days after purchase, Heath Company will replace or repair free of chage any parts that are defective F
eitheiinmaterialsoiworkminship.ioucanobtainpartsdirectlyfromHeathCompanybywritingusattheaddressbeloworby 3F
telephoning us at (6161 982-3571. And we'll pay shipping charges to get those parts to you - anywhere in the world. t?
We wurant that during the first ninety [90) days after purchase, our products, when correctly assembled,calibrated, adiusted 3=
and used in accordance with our printed instructions, will meet published specifications. ==
If a defective part or error in design has caused your Heathkit product to malfunction during the warranty period through no ?=
fault of yours, we will service it fiee upon proof of purchase and delivery at your expense to the Heath factory, any Heathkit *<=>
Electronic Center (units of Schlumberger Products Corporation), or any of our authorized overseas distributors. 5:
rc
You will receive free consultation on any problem you might encounter in the assembly or use of your Heathkit product. ]ust !€=)
drop us a line or give us a call. Sorry, we cannot accept collect calls. =
Our wananty does not cover and we ile not responsible for damage caused by the use of corrosive solder, defective tools, *€
incorrect assembly, misuse, fire, or by unauthorized modifications to or uses of our products for purposes other than "t 3=
advertised. Our warranty does not include reimbursement for customer assembly or set-up time. ?=
This wananty covers only Heathkit products and is not extended to allied equipment or components used in conjunction with {--
ourproducts.Wearenotresponsib|eforincidentalorconsequentia|damages.Somestatesdonotallowtheexclusion
limiiation of incidental or consequential damages, so the abovi limitation or-exclusion may not apply to you. fhl, *'a".atiy =
gives you specific legal rights, and you may also have other rights which vary from state to state. 1i;
lF-
Prices
andspecificationssubject
to changewithout
notice

Heathkit@
Manual
forthe
VIDEO
TERMINAL
Model
H9
oPERATION 595-2017-03
HEATH COMPANY
tsENTON HARBOR, MICHIGAN 49022
Copyrlght
@1977
HeathCompany
Ail RightsReserved
Printed in tho United Stat€8 of Amorica

Pase2 @
TABLE OF CONTENTS
INTRODUCTION.
OPERATION
Local Function Keys
Special
FunctionKeys.
ControlCharacters
HoIdScreen.. ..
SYSTEM
CONSIDERATIONS
HeathkitComputerSystemInterface
Standards
General
Interfacing
READIUSTMENT
Brightness
Focus
Centering
Height
width
RepeatRate .
Cleaning
SPECIFICATIONS
TROUBLESHOOTING
Troubleshooting
Charts.
.. ..
Troubleshooting
Waveforms.
ShippingInformation
4
5
8
B
10
L2
26
26
26
27
28
30
30
32
CIRCUITDESCRIPTION
BasicOverview.. ....47
PowerSupply .......48
Video
Circuits ....... 48
CharacterGenerator .....,..50
KeyboardCircuitBoard ....54
RAMandCounter ... 55
Timing andProcessing
Unit (TPU) .. .... 57
Input/Output
(I/O) ... 66
SEMICONDUCTORIDENTIFICATION
ComponentNumberlndex ........68
PartNumberlndex ...71
ROM
andPLAPrograms
.. ....... 85
X-RAYViews ... (Illustration
Booklet,Page
74-23)
SCHEMATIC.... Fold-in
WARRANTY.... .. Insidefrontcover
CUSTOMER
SERVICE .... Insiderear
cover
33
35
43
46

INTRODUCTION
The Heathkit Model H9 Video Terminal candisplay
information coming from a digital computer or in-
formation typed in from the keyboard.This informa-
tion isdisplayedortaL2"
(diagonal)
cathode
raytube
(CRT)
that is capableof displaying 960charactersat
onetime (12rows with 80 characters
perrow).
A 67-keyASCIIkeyboard,
which permitsyoutocom-
pose
andedit directly ontheCRT, has
acapabilityof
64 different characters and zq different functions.
This messageorprogram canbetransmittedthrough
the standard
serial
I/O interface
(EIA,
TTL, or 20
mA
current loop) to a digital computer or through the
parallelI/O interfaceto a paper
tapereader/punch.
The Video Terminal can be used with any digital
computerin adedicatedformat,in astand-aloneap-
plication, or in a time-sharing system.It lets you
communicate
with adigital computer in higher-level
language (Basic,Assembler,etc,) rather than just
using toggle switches.
The Video Terminal is also
much faster(up to 9600 baud) than the standard
electro-mechanicalteletypewritersystems.You can
selectany data
ratebetween
110and g0OO
baud.
Otherimportant features
include:
. Automatic scrolling
. Cursorcontrols
. Eraseto end of line
o Erase
page
o Short form (four 12-line columns of zO
characters)
o Automatic line carryover
. Plotmode
o Built-in speaker
(audiblebell)
o Transmit page
These features,along with the attractively-styled
cabinet, make the Video Terminal a versatile
peripheral
for your computersystem.

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OPERATION
The Video Terminal will generate
and display 64
ASCII codedcharacters.
They include the alphabet
(uppercase
only),numbers,
punctuation,andmany
symbols.
Thirty-two standard
controlcharacters
and
twenty-four special
functionscanalso
begenerated.
Pictorial
1-1
(Illustration
Booklet,
page
1)
shows
the
location
ofthekeys
described
in thefollowing parag-
raphs.
LOCAL FUNCTION KEYS
Thelocal
functionkeys
donottransmit
ASCII
charac-
ters;
they only affect
the display.
CURSOR CONTROL KEYS
These
keysareon the far right of the keyboard
and
they arelabeled
with arrows.
These
keysmove
the cursorone
character
position
or one character
line asindicated
by the arrow.
HOME
This keymoves
thecursor
to thefirst character
loca-
tion on the first line.
ERASE EOL (End Of Line)
Thiskey erases
thetextfrom the currentcursor
loca-
tion to the end of that line.
ERASE PAGE
Thiskeyerases
alltext
and
fills thepage(screen)
with
spaces.It also places
thecursor
in thehome position.
uP
cuRSoR(f)
DO\
lrri
CURSOR
(+) I
RIGHT CURSOR
(---,)
|
LEFT CURSOR
(<-)

-
Page5
@
AUTOCARRY
Whenthis keyispushed
in, thecursor
automatically
goes
tothe
beginningof
thenext
lineafter
a
full line of
textistyped.
At theendofthebottomline oftext,the
cursorwill startoveratthebeginningofthefirstline
fhome position),
providing the Terminal is not in
scrollmode (SCROLL key released).Also, referto
"Hold Screen"
onPage8.
SHORT FORM
When this key is pushed in, the display format is
changedfrom twelve lines of 80 characters
fkey re-
leased)to four columns - eachcolumnconsistingof
twelve lines of 20characters.Short form isusefulfor
writing programs in machinelanguage
where
entries
areshort.
SCROtt
Whenthiskeyispushed
in, andafterthefirst twelve
linesoftextaretyped,thefirstline iserased
(scrolled
upwardJ and lost. Each remaining character line
movesup one line position andthecursormovesto
thebottomline.In short
form,the left column of 24o
characters
[12 lines of 20 characters)
is erased and
lost.The remaining three columns move to the left
onecolumn position,
and the cursormovesto the
right column.
When
theSCROLLkeyis released
(in
the non-scroll
position),
and afterthe first twelve
lines of text are typed, the cursorreturns to and
flashesat the start
of pageposition.Furthertyped
entrieswill write over the existing text on the first
line.Also,refer
to "Hold Screen" onPage
8,
SPECIAL
FUNCTIONKEYS
RETURN (Carriage Return)
Thiskeymovesthecursor tothefirstcharacter
posi-
tion of the line it is currently in and it transmitsthe
ReturnASCIIcode
(control
M).Return canbewritten
into aRAM locationonly if thatlocation
contains
a
space.Thatis,acarriage
returnwill notwrite overany
other character.
Returnis a non-displayablecharac-
ter,except in theplot mode.
LINE FEED
This key moves the cursor down one line and it
transmitsthe line feedASCII code(control )). Line
feeddoesnot write into RAM andit is not a display-
ablecharacter,except
in the plot mode.
RUB OUT
Thiskeytransmits
anASCIIruboutcode
(delete).
Rub
out does not write into RAM and it is a non-
displayable
character,
exceptin the plot mode.
ESC(Escape)
This
key
transmits
anASCII
escape
code.
Escapedoes
not
writeintoRAMand
itis
anon-displayablecharac-
ter,exceptin theplot mode.
REPT (Repeat)
When this key is held in, along with another key, it
will repeatthefunction oftheotherkeyata
preset
rate
aslong asboth keys are held down. The presettable
repeatrates
are 3.7-,7.5-,L5-, or 30-characters
per
second.If the baud ratethat hasbeen selected
is less
thanthe
repeatrate,
therepeatfunction will operate
at
the slower rate.

PLOT
Whenthiskeyispushed in,thetextisblankedexcept
forthe firstline of thepage. Thisfirstline,however,is
displayed on each of the four bottom lines of the
screen.Thescreenareaabovethebottomfour linesis
dividedinto128scan
lines.
See
Pictorialr-2.A dash,
one character
wide, will appearaboveeachof the
charactersdisplayed
in the bottomfour lines.The
position
ofthedashabove
thebottomline (line 0)is
proportional
to the binaryvalue of the z-bit ASCII
code
for that character.For example,aCTRL/SHIFT
P,
orASCII null, isall zeros,
so
itsbinaryvalue
iszero,
and it appears
at the bottomof the 128line space
directly abovethe ASCIInull. Pictorial r-g fllustra-
tion Booklet,Page2)gives
theline numberandthe
ASCII
codefor eachkeyentry. A RUB
OUT (delete)
or
all ASCIIL's
hasa binaryvalue
of 727, sothe dash
appearsatthetop line (line128)in thespaceabove
therub out character.
In theplot mode,
all charactersare
written intoRAM,
but their special cursor movements are not im-
plemented.That is, a RETURN(carriage return) is
written into RAM,butthecursordoesnotmove.Any
control characterthat appears
in the text will flash.
Even though the lower-casealphabetic
characters
cannotbegeneratedfrom thekeyboard,
theycanbe
LINE
(B
INARY
VALUEI27)
LIN
(B
INARY
VALUEO)
entered into RAM from the digital computer, Like all
other characters, the binary value of the lower case
charactersis stored in RAM and the dash is d.isplayed
on the appropriate line in the 128-line space. Lower
case characters stored in RAM are displayed as the
characters represented by the ASCII words 010 0000
through o17 71,'17.
BAUD RATE
Whenthis key is released
(out),
the Terminal will
operateat 110baud.Whenthiskeyispushed
in, the
rate is set by the BAUD RATE switch on the rear
panel.
Therear
panel
switchselectseither
300baud
orthe
preset
baud.
Thepreset
baud
isdetermined bya
jumper
wire ontheI/O circuit board.
OFF LINE
When
this
key
is
pushed
in,the Terminalisinhibited
from transmitting or receiving data from the serial
I/O,
but it doesnot interrupt
transmission
or recep-
tion through
the
parallel
I/Oport.
Thislets
you punch
or
read
tape
on
the
paper
tapereader/punch
whilethe
Terminal
is offline from the digital computer.
NON-
',iil,
r^rc
3iililfijfi
PICTORIAL \-2

Page 7
@
%
BREAK
Whenthis keyispushed
in, it generates
acontinuous
space
at the serialoutput, It is generally
used
to tell
the
computer
that
youwishtointerruptexecution.
Do
not confuse
this spacewith an ASCIIspace.It is de-
fined as
zero
currentin a20mA current
loop,anEIA
positive
voltage,
oraTTL logic 0.TheBREAK
keycan
bepressed
anytime you want to terminate
thetrans-
mit page
function.
FULL DUPLEX
Whenthis keyisreleased
(out),
theTerminaloperates
in the half duplex mode. That is, data from the
keyboard or parallel input is written directly into
RAM and,at
thesametime,ASCIIcharactersare
sent
out the serialand parallel outputs.When the FULL
DUPLEX
key is pushedin, the Terminal operatesin
thefull duplex mode.Data
from theparallelinput or
fromthekeyboard
issenttothecomputerand
echoed
backtotheTerminalbeforeit iswritten into RAM and
displayedon the screen.
XMIT PAGE (Transmit Page)
Whenyou momentarily press
this key,data is trans-
mitted from the RAM (screen),
startingfrom the cur-
rentcursorlocationandproceeding
to theendofthe
page.When it has completed the page,
the cursor
returns
homeandthetransmitpage
modestops.The
dataistransmitted
simultaneously
outboth theparal-
lel andserialports
atarate
determined
by theslower
ofthe
two ports.
Press
theBREAK
keytointerrupt the
transmit page
function.
CTRL (Control)
When
thiskeyisused
in conjunction
with some
of
the
otherkeys,
it changes
those
keys
to special
function
keys.
Forinstance,
CTRLM is equivalent
to areturn
(carriage
return).The control key combinationsare
shown
in Pictorial
1-3.
SHIFT
When this key is usedin conjunction with another
key,
thecharacter printedontheupperportion ofthat
key will bedisplayed.
Since
theTerminaldoes
not
generate
lower-case
alphabeticcharacters,
it is not
necessary
topush
theshiftkey
togenerate
upper-case
alphabeticcharacters
- they are shifted automati-
cally in the keyboard
encoder.
CTRL/SHIFT
These
two keysareused in conjunction with other
keys
toprovideadditional specialfunction keys.For
instance,CTRL/SHIFTP (which means, press the
CTRL,
the SHIFT,and the P keysat the sametime)
putsanASCII
null fall zeros)
on thebus.

t"n"t @
CONTROTCHARACTERS
The Terminal generates
all 32ASCIIcontrolcharac-
tersfrom thekeyboard.
Normally these
charactersdo
not write into RAM, nor arethey displayed on the
screen.Exceptionsareoutlined in the description of
the plot mode.TheTerminal recognizes
only four of
thecontrolcharacters.It will recognize
thesefromthe
keyboardor from the parallel or serial input ports.
The four characters
are:
Line Feed
(LF or CTRL
]) - This characterdu-
plicates
the LINE FEEDkey.
CarriageReturn(CR
or CTRLM) - This charac-
ter duplicates
the RETURN
key.
Back Space
(BSor CTRLH) - This character
movesthe cursorto the left onecharacter
posi-
tion without disturbingthe characterbeingdis-
played.
Bell(Bel
or
CTRL
G)
- Thischaractercausesthe
Terminalto soundashortaudibletonethrough
aninternalspeaker.Pictorial 1-3
showsthecon-
trol andnormalcharactersthattheTerminal can
generate.
HOLD SCREEN
If the screenhasbeenfilled, and a scroll function
should occur,but can't becausethe SCROLLkey is
notpushed in,theTerminalgoes
intothehold screen
mode.Thecursor returnstothe startofpage location
andblinks.All external
inputsare
disabledwhenthis
occurs.Datacanonly be
transmitted outoftheTermi-
nal by the keyboard.The Terminal stays
in the hold
screenmode until the SCROLL
key is pushedin or
until the ERASE
PAGEkey is pressed.
Youcanusethisfeature
in conjunction
with thepaper
tapereader/punch
for reviewing programtapes.
The
reader/punch
canread
thetape
atitsmaximum speed
tofill upthescreen
quickly,thenafterthelastline has
been written, the hold screen mode disables the
handshake
signal coming from the Terminal. This
stops
thetape
fromrunning. You can
thenreviewthe
contents
of the screen.
When you arefinished, just
press the ERASEPAGE key and receive another
screenfull of programinformation automatically.