Curtis Computer kb4900 User manual

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ASCII, BAUDOT AND MORSE
KEYBOARD
ONNER’S MANUAL
TABLE OF CONTENTS:
Description . ....................... 3
Commands ... ........ ........... ..... 5
Specifications..................... 7
Dperation....... ................... 9
General Operation.................. 12
Operation on 12v. ..... ............. 15
Circuit Functions ..... ............. 15
Ca1ibration..... ....... ............ 15
In Case of Difficulty .............. 16
Limited Warranty....... .. .......... 16
Program Changes and Revisions...... 16
Assembly Drawings and Schematics... 17
Code Practice Lists...... ..... ..... Appendix A
CIRCUITS AND EPROM CONTENTS COPYRIGHTED 1980, ALL RIGHTS RESERVED
CURTIS ELECTRO DEVICES, INC., BOX 4090, MOUNTAIN VIEW, CA 94040

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Your KB—490O is aproduct of the computer age. Unlike its predecessors
the KB—42OO AND KB-4800, this unit does not use discrete dedicated parts to
perform its function. Instead, it employs an "all purpose" IC called an
integrated microprocessor. This device does nothing itself, however, when
provided with alist of instructions, it will carry them out and in so doing,
accomplish the objectives of the programmer who devised the set of instruct‘
ions. The KB—4900 uses amicroprocessor called the 5035 (developed by the
Intel Corporation). The 9035 contains an 8-bit central processor unit (CPU),
512 bits of random access memory (RAM), 27 input—output lines (1/0) and
an B~bit timer/event counter.
For instructions, we use the 2732 (Ultra-Violet) Eraseable Programmable
Read—Dn1y Memory (EPRDH). It can contain as many as 4,096 individual
instructions composed of 32,768 individual bits. The sending buffer and
message storage are implemented in another powerful IC, the 2114. This
Random—Access Memory (RAM) will store 512 Esbit bytes in its 4,096 read‘
write storage cells, and last, but not least, the venerable 9044 single
chip keyer IC provides the Morse code generation in order to free the
processor for more complicated tasks. For those of you interested in
statistics, the circuitry in the KB—4900 contains approximately
100,000 individual transistors.
The program for the KB—4900 uses most of the 4,096 instructions possible
from the 2732. From alibrary of 90 individual instructions recognized by
the microprocessor, the program is built-up into asequence that provides
the function of the KB—4900. The microprocessor winds its way through the
program at the rate of 400,000 instructions per second. And, while it looks
as though things are being done all at once, in reality they are being done
one—by—one. The processor does everything serially except that it handles
all data in groups of eight binary digits called bytes. The processor is
unbelievably busy while the unit is operation, executing the prescribed
program at the 400 KHZ rate. It is not unlike ajuggler keeping many plates
spinning at one time. Though we have only one juggler, there is awhole
lot of activity going on. In the case of the KB«4900, it may be sending DU,
accepting new key inputs, assigning spaces in the sending buffer, unloading
the sending buffer at some other point, running the buffer meter, running the
speed meter, holding the PTT line down, watching for buffer overflow, keeping
track of the time. incrementing the serial number, and scanning the keyboard
for new commands....400,000 times asecond without mistakes!
The program for the KB—4900 consists of 78 pages of single spaced text. It
took nearly six months of writing, testing and debugging to get
the program ready. we hope you enjoy using the system as much as we enjoyed
designing it, If you have suggestions on how we might improve the unit,
don’t hesitate to call or drop aline.
(D

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ISENDS
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KSENDS
MORSE FROH KEYBOARD
HORSE FROM PADDLE KEY, MANUAL KEY
BAUDOT CODE FROM KEYBOARD
ASCII CODE FROM KEYBOARD
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OR BUG
TRUE RANDOM HORSE FDR CODE PRACTICE
PSUEDO RANDOM MORSE IN 8~l5OO CHAR. LISTS OF 5-LETTER GROUPS N/ANSWERS
Sends Morse code from the keyboard or from an external paddle key at
any speed selected by the speed control.
Analog controls (potentiometers)
sidetone pitch and sidetone volume.
An analog meter readout of buffer status
the fullness of the sending buffer which
(overflow lamp and pitch change on Horse
A "BUFFER HOLD" function allows break—in
key is operational during the hold.
An analog meter readout is also provided
readout. This is calibrated from 5 to B0
either keyboard, paddle initiated keying
are also provided for weight,
continuously indicates
can contain as many as 256 characters.
signals nearly full buf#er)
operation. The paddle
for Morse code speed
upm and is effective for
or random code practice.
Push—to—talk control is provided for transmitter switching
in all modes. PTT release is delayed 0.5
Special prosigns AS,SK,BT,AA,KN, KA plus
commercial.
Four programmable message memories (A,B,E &D)
seconds {or convenience.
most European and
are provided. These
can consist of one to four messages whose total is 256 characters.
Messages are called via the sending buffer.
partitioned, meaning that “B”
imum use of the memory storage.
The memories may be "chained"
Memories
always starts wherever
The {our memories are soft
"A" ends to make max-
"C. and "D"
via the buffer.
(Warning lamp for overflow during load is provided)
(3)
follow in the same manner.

Automatic bu11t'in messages are provided as follows:
CG CG DE (message A) (i.o. "KbKU")
CD TEST DE (message A)
DE (message A) (This is the "ID" key)
QRZ (message A)
(Note that these are appended by programmable message “A“)
Two key lockout operation of keyboard prevents lost characters
during "burst" typing.
A"DELETE" key allows correction of errors prior to transmission.
An automatic incrementing serial number from 0to 9999 is available
for insertion into the sending buffer or the message memories for contests
which require sequential numbering. Leading zeros are not transmitted.
Arepeat Function allows repetition of any o¥ the Four message memories
a5ter apresettable period of from 1 to 99 seconds.
9real—time clock option allows generation of atime transmission
(24-hour Format, 1.e. 21:42) in Morse, Baudot or ASCII. Time can be
inserted in the sending buffer or any message memory. Time is sent
as 21R24 in Morse, 21:24 in ASCII and Baudot.
BAUDOT CODE:
Baudot (S—level) TTY code is transmitted ¥rom the keyboard at
50 wpm standard speed. (45.45 baud)
Both RTTV and Cw ID are provided ("ID“ key)
High voltage &OmA. loop keying transistors are built into the unit.
Provisions are made for mixing receiver audio and keyer
sidetone For convenient monitoring.
Carriage return, line feed and "LTRS" are sent automatically
after 63 characters and aspace have occurred on a line. After 70
characters, the Function is initiated without any space being present.
This makes nice looking copy at the receiving end, with the carriage
return not breaking words. Also this frees the operator 4rom worrying
about the carriage return.
All up and down shift is handled automatically. In addition,
adounshift occurs on every space to quickly clear any garbles in recept-
ion.
As with Horse transmission, included are the sending buf§er,
the programmable message memories, the automatic message sequences plus
the "DELETE" function and KUS (Key-DperatedASwitch) control.
ASCII:
Same as Baudot above except that Functions involving up and down
shift (FIGS and LTRS) are not required.
Transmission speed is 110 baud.
Both upper and lower case are generated (upper case by shifting)
G"CAPS LOCK“ function allows transmission of capital letters only.
(4)

NURSE PRACTICE:
Mode 1: Random length groups of random characters are sent in anever
repeating sequence at the speed selected by the speed control. Extra
spacing between characters can be selected for easier study when trying
to make large speed increases.
Mode 2: Psuedo random five character groups are sent, however, unlike the
above true random generation, this second mode sequence is always the same
and answer lists can be provided. There are eight lists available and are
called by placing the number "1" through “E” in message memory "A". If
any other character is placed in message memory "A", the mode 1 random Horse
will be sent. The sending stops at the end of each list. To restart, use a
system reset and restart the program.
with both modes, you can insert extra space between letters by pressing
the "CTRL" key followed by the "5" key.
Also, with both modes, you can eliminate numbers and punctuation by placing
an "N" after the “R” or number "i" thru "8" in message memory "A".
C3C3P1P1F§FJI)S3- -_--------------------- - - -
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1 (NOTE: "CTRL-X“ MEANS PRESS THE "CONTROL" KEY, RELEASE, THEN PRESS "X") X
I(SHIFT/X MEANS HOLD THE SHIFT KEY WHILE DEPRESSING THE "X") 3
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NURSE HDDE: CTRL-1 (Automatic after system reset)
Unmarked prasigns:
:SH/A
SH/Q
:SH/E
N: SH/N
D: SH/D
U: SH/U
CH: SH/C
ATTENTION: SH/T
HYPHEN: SH/H
UNDERLINE: SH/L
UNDERSTDDD: SH/K
SEPARATION: SH/S
BAUDDT NUDE: CTRL—2
CR: SHIFT/.
LF: SHIFT/,
LTRS: SHIFT/;
BELL: SHIFT/AS
RTTY ID: "ID"
CH ID: CTRL-"ID"
(S)

ASCII MDDE:
CR:
LF:
BELL:
RTTV ID;
CH ID:
RANDOM CODE:
SLOW NUDE:
NUDE l:
MODE
PAUSE:
ALL MODES:
LOAD MESSAGES:
READ SERIAL NR:
PRESET SER. NR:
TRANSHIT TIME:
PRESET TIME:
REPEAT MODE:
PRELOAD
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MODE:
"A":
"Bu:
"C":
"D":
CTRL—3
SHIFT/.
saxrr/,
SHIFT/AS
"X9.
CTRL-"ID"
CTRL—4 (standard
CTRL-5 (extended
Place any letter other than 'thru "8" in message "A"
Place letter "1" through "E" in message memory "A"
Press SHIFT and hold one second; to release, press SHIFT again
spacing)
spacing)
CTRL-At,
(Note:
send message,
Message
then ETRL again (for message "A”)
"A" normally will consist of your call letters)
ETRL—Bt, send message, then CTRL again (for message "B")
As above for "C" and "D"
(Lamp lights two characters before full. In addition,
the buffer meter indicates the amount of message memory
storage space used)
(Message "A" must be programmed be+ore message "B",
any change [of length] in "A" will affect message "B").
The same is true of "C" and "D", i.e. program "A" first,
next, "C" next and "D" last. Any later change of length
in apreceding message will disrupt the following messages.
also
nsu
SHIFT/6 (This does not increment the number) SHIFT/5
can be inserted in message memories "A" through "D" where
each use will increment the number.
CTRL—b followed by four digits (most significant first).
Use CTRL—I to increment, CTRL-D to decrement
SHIFT/At
CTRL-7 followed by four numbers (NSD first).
started at zero seconds as last number
Clock is
(LSD) is entered.
Preset delay interval in number oi seconds by pressing
CTRL—-(dash) {allowed by two digits (NSD first). Messages
A! through D! will then repeat automatically until the
SHIFT key is pressed (during delay) to release and reset
delay to zero. The overflow lamp lights during the delay
interval for monitoring.
Type SHIFT/SPACE, then CTRL to release
(Lamp warning for overflow). Can also use SHIFT/SPACE bar.
"Au!
nan‘
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(6)

CR MESSAGE (CG CG DE [message A]); type SH/"C"!
CD TEST MSG (CG TEST DE [message AJ); type SH/"D”t
“ID” "ID" key
QRZ MESSAGE: SH/"B"!
PRELUAD BUFFER: SHIFT/SPACE bar (CTRL to release)
HOLD BUFFER: SHIFT/SPACE bar (CTRL to release)
DELETE LAST KEY: "DELETE" key
DELETE LAST WORD: "DELETE" key (from sending buffer only)
MESSAGE RESET: RESET!
BUFFER RESET: RESET!
SET SPEED: Press ETRL—B and adjust speed pot, any key releases
TUNE: Press CTRL~9, SHIFT to release (gives continuous dots)
(3 Note: Keys followed by an "3" are the NHITE keys.)
E3F’EZ(3 IIF7 I C3¢§"T'I CJBJSS -- -- - ____--------- - -
SPEED:
MORSE RANGE: S TU BO NPM (Upper end user adjustable higher or lower)
BAUDDT: 45.45 baud (60 upm). 8unit code: 1 START, 5DATA, 2 STOP
ASCII: 110 baud. 11 unit code: 1 START, BDATA, 2STOP
SENDING BUFFER:
256 keys
MESSAGE MEMORIES:
256 keys total, soft partitioned into Four sections
FIXED MESSAGES:
CD CG DE (msg "A")
EQ TEST DE (msg "A")
DE (msg "A")
DRZ (msg "A")
Incrementing serial number
24vhour tine
MONITOR:
Internal sidetone generator and speaker, volume and pitch adjustable
KEYBOARD:
54 key alphanumeric plus space bar, punctuation and prosigns
(AA,KN,BT,AR,AS,SK,KA plus European A,A,E’,D,U,CH AND N. also
commercial "ATTENTION", hyphen, underline, "UNDERSTDOD" and
"SEPARATIDN“).
Gold inlaid key contacts individually replaceable. Sculptured
and tilted two-shot molded keycaps. One character produced
per key depression. Debounced and "TNU—KEY LOCKOUT”.
MANUAL KEYINB:
with external straight key.
PADDLE KEYING:
with external paddle key, iambic with dot and dash memories.
(7)
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5”/7’ =/F7? =/477$/I/7'iaxV

INTEGRATED CIRCUIT CDHPLEHENT:
B035, 2732. 2114, 74LS75 (2), 74LS1b4,
lLD74(3), B044, 741-LS175, 7805
Euxth real-time clack option HC14518B (3)1
INPUTS:
RECEIVER AUDID...B Ohm!
PADDLE KEY.......Single or twin lever (optically xsolated)
MANUAL KEY ....Telegraph key (optically isolated)
12 Vdc.... .....10 T0 14 Vdc 3 500 mA.
OUTPUTS:
KEYLINE... .300V, 500mA max. mercury relay
PTT...... ....300V, 500mA max. mercury relay
LDDP...... .....30OV, l00mA max. (optically isolated)
TTL TTY... .....TTL level, sink or source 5 MA
SPEAKER... .....8 Ohms or headphones
POWER REQUIREMENTS:
1l7Vac S0—60 HZ,10VA OR 12Vdc 9 500 mA.
234Vac 50-50 HZ by special order
SIZE:
12" wide xB-1/2" deep x4-1/2" high.(30.4B X21.95 x11.43 cm)
WEIGHT:
5.5 lbs. (2.49kg)
FINISH:
Panel is light grey, bottom and side panels are textured black.
(lettering in white, yellow and red)
PANEL CUNTRDLSI
Speed, weight, pitch and volume controls; tune/self—test
switch, power switch, system reset switch, overflow warn-
ing lamp, illuminated speed and bu+{er status meters.
REAR PANEL:
Jacks For l2Vdc, TTY loop, TTY TTL level output, paddle key,
manual key, transmitter keyline, transmitter PTT,
receiver audio, and external speaker Dr headphones.
117 Vac receptacle and ¥use.
(SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.)
(8)

C3F°EZF?é§1']iC3FJ- --------- - - - - - - - - - - - - -
Note: Use shielded cable {or all interconnections between the KB—4900
and other units including the keys.
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Always connect all the transmitter cables before connecting the ac
line to the KB~4900. This prevents problems from minute ac leakage
from the ac line bypass capacitors in the KB—4900
Also, make sure the unit is equipped for the line voltage you are using,
i.e. either 117 DR 234 Vac.
Place the "TUNE/DP/SELF—TEST" switch in "SELF-TEST" until you are ready
to go on the air. "SELF—TEST" disables the keyline and PTT relays.
CW KEYBOARD:
Connect the keyline of your transmitter to the jack marked "XMTR“ on
the rear of the KB—4900. Connect the PTT line of your transmitter to
the jack marked "PTT" on the rear of the KB—4?00 (or you may use
aseparate hand or foot switch for PTT as some operators prefer).
Connect apaddle key and amanual key to the respective jacks on the
rear o4 the unit if you plan to use them.
Set the SPEED control at midrange. the WEIGHT control at full CCN, the
pitch and volume controls at midrange {or start-up unless you have
already set them where you like. Use the HEIGHT control very sparingly
ii at all. It is normally used only at speeds up to about 20 Hpm except
to compensate for slow acting transmitter keying. Use of more than avery
slight weight addition is not amark of excellent operating practice and
Mr. Horse didn’t intend it. But it will smooth—up slow speed transmission
abit.
Connect acable from the 8 ohm audio output of the receiver to the
jack marked “RCVR” on the rear of the KB—4?O0 if you intend to use
the "SPKR” jack of the KB—49OO to listen to mixed sidetone and receiver
audio. Note that the RCVR and SPKR jacks are simply connected in parallel.
The KB—4900 comes on in the cw mode. To go to the Cu mode from
either the Baudot or ASCII mode, thpe CTRL-1. If in the random
practice modes, press the SYSTEM RESET switch.
Set the desired speed by either sending characters and adjusting
as you listen or type CTRL-B and adjust the SPEED pot until the
desired speed is read on the speed meter. Press the SPACE key to
release from this mode.
Preset the time and serial number if desired by referring to the
GENERAL DPERATIDN section. Similarly, preload the message memories
as described in the GENERAL DPERATIDN section.
(9)

Move the "TUNE/DP/SELF—TEST" switch to “UP” and the transmitter will
key in the CM mode. Vou may tune the transmitter either by typing
CTRL-9 or by placing the "TUNE/OP/SELF-TEST" switch in "TUNE". CTRL-9
will give you astring o4 dots to avoid overheating the transmitter
final stage during protracted tuning. The "TUNE" switch holds down
both the keyline and the PTT line.
By sending either from the keyboard or the paddle, both the keyline and PTT
circuits will be activated, the PTT line will wait about 0.5 seconds before
opening for convenience. The PTT line is not activated by the manual
key.
BAUDOT KEYBOARD:
Connect acable from the loop circuit of your printer and TU (Terminal Unit or
modulator/demodulator) to the jack marked "LOOP" on the KB—4900. This
jack is isolated From the chassis and the internal circuitry of the
KB—4900. It will work with either polarity o{ dc and is rated to key
up to 300 Vdc at l00 mA max. Host amateur loops are approximately l9O
Vdc at 60 mA. Make sure the TU loop is deactivated during hook-up,
otherwise the 190 Vdc will appear at the exposed end of the loop
plug causing apotential electrical shock.
Also, connect acable from the PTT line and keyline of your transmitter
to the respective jacks on the rear of the KB-4900 (PTT to "PTT", KEYLINE to
"XHTR”.
To go to the Baudot mode, type ETRL-2. Now, typing on the keyboard will
key the loop circuit. To go on the air, place the “TUNE/DP/SELF~TEST"
switch in TUNE before starting transmission. This will close both the
keyline and PTT circuits placing your transmitter in the RTTY mode
where the characters are transmitted by FSK (Frequency Shift Keying).
Type just as on anormal typewriter, all LTRS and FIGS shifts are done
For you automatically in addition to all end~of-line carriage returns
and line feeds. At the end of your transmission, return the "TUNEIOPI
SELF—TEST" to "UP".
Note that at the beginning and end of your transmission and at ten
minute intervals during the transmission, you are required to send
your call letter identification. Pressing the "ID" key will send
the ID in RTTY, pressing "SHIFT/ID“ will send your CH ID over the
loop circuit. This assumes you have loaded your call letters into
message "A" as described in the GENERAL OPERATION section.
If you experiment with the code speed, you will find aspeed
(around 13 wpn for Baudot) where the printer will print all O’s during the
ID.
I¥ you want KDS (Keyboard Operated Switch) carrier control, connect
the KB-4900 PTT output to control your transmitter keyline and/or
PTT line, a0.5 second delay on PTT dropout will allow momentary
pauses. You will need to "diddle" with the "LTRS" key to prevent
dropout otherwise.
(10)

TTL TTY Output: If you want to drive your external RTTY equipment
with aTTL level instead of the current loop, open the unit by removing
the four screws on the bottom and remove the jumper plug from
P3 on the keyboard PCB. This puts agood TTL level on the rear
jack marked "TTL TTY". This signal will also satisfactorily drive
some EIA level receivers. If you don’t remove the jumper, the high level
at the rear jack will be invalid
ASCII KEYBOARD:
Same as above for Baudot operation except that you can send both
upper and lower case after pressing SHIFT/CTRL. The unit comes up
in the CAP LUCK node where all alphabetic characters are transmitted
as capital letters. when not in the CAPS LOCK node, use the SHIFT key
for upper case the same as on atypewriter.
DUDE PRACTICE:
You have achoice of two general modes of random code practice. The first
is true random where the sequence is in groups of random length which never
repeat exactly the same way. Call up this mode by placing an "R" in message
memory "A" and typing CTRL—4 or CTRL—5 (see below).
The second mode is PSUEDU RANDOM code where the groups are always five
characters in length and will repeat exactly every time they are played.
There are eight different lists called by placing anumber from 1 to B in
message memory "A" and typing CTRL—4 or CTRL-5 (see below). The eight
code lists are available for checking. They run about 1500 characters each.
To halt the code practice (for chow call etc.), press the SHIFT key
for one second. To restart where you left off, press the SHIFT key for
one second again. (Incidentally, halting code practice stops the real~time
clock also.
Practice will stop at the end of each list. For the true random
mode, practice will continue indefinitely until you hit the SYSTEM ESET.
For normally spaced practice, use CTRL-4 to commence the code, for code
with extended spacing between letters (quasi-"Farnsworth Hethod"),
type CTRL-5 to commence the practice.
If you desire only the alphabetic characters (no numbers or punctuation),
load an "N" in message "A" after the "R" or number loaded for true random
or psuedo random practice.
The speed of code practice is set by the "SPEED" control and the speed
meter indicates the speed of character generation. Note that ypu’re
cheating in the extended practice mode so the wpm indication isn’t
correct though the speed of individual letters is correct.
Use SYSTEM RESET to exit from the practice nodes.
(11)

C3EEDJEEF?£§l_ CJF>EEF?£)‘r.IC3fQ- -----_---- - _ - - - - -
Usually the first step when you begin operation is to load at least
message memory "A" since you will use it constantly. Preloading messages
"B“,"C" AND "D" is at your option. For contest use, the messages to load
here will be obvious except perhaps for the serial number which will be
inserted in some fashion in memories "A“,“B" UR "C" such as "UR NR --—-,
QSL?" or something equivalent. The serial number will increment by one
each time it is used in message “A",“B“,”C" DR "'. You may also imbed
the time in one o¥ the messages if you like. For example, you might
prepare the message "TIHE HR l5 -—R—— GMT 12/24/30". For the other messages,
you can load in sequences like "TNX FER RPT —UR SNN IN NEST PDDUNK, TX “
NAME HR IS TEX ~TEX —RIG IS 50 AND SO RUNNING FIVE WATTS TO A FUURTEEN
ELEMENT YAGI ‘SD HW? ". You are limited only by your imagination and
the 256 characters total you can load in the {our memories.
PRELDADINE THE ESSABE MEMORIES:
The procedures for loading each of the message memories "A" through "D"
are the same except that you must proceed From "A" to "B" to "C" to "D".
The reason For this is that "B" starts at the end of “A”, "E" starts
at the end of "B" and "D" at the end of "C". This method is used to
get maximum utilization of the available memory. If you change "A","B"
or "C" (unless the length stays the same), you must redo the following
messages also.
Note that you may have one long message, {our shorter ones, one short and
one long or any combination of one to four messages the total of which
may not exceed 255 characters (keys).
Normally, message "A" will consist only of your call letters. To prepare,
type CTRL—Al (the white "A“), type your call letters and then hit the
"CTRL" key again to release from the load mode and end the message.
You can include any key or shitt combination in the message including
the time or incrementing serial number. But not including the fixed
messages (CD,CD TEST. QRZ AND THE ID’S)
Prepare the other message memories "B" through "D" the same way using
white keys B,C AND D.
when you have space for only three characters (keys) left in the
TOTAL memory, the OVERFLDN lamp will light and you will have to
stop accordingly. You may have to redo message "D" if you’ve stopped
at an awkward place. Abort from the load by terminating with a"CTRL"
key stroke.
Note that the serial is called by typing SHIFT/6 and the time is called
by typing SHIFT/At (white key). Put aspace after the serial and before
and after the time.
PRESETTING THE SERIAL NUMBER:
Type ETRL-6 and type four number digits starting with the most
significant number, for example type the 3 first if presetting
the number 3456 or type the 0 first if presetting 0135. or type three
0’s first if presetting 0003 etc. Normally, you will start acontest
by presetting 0000. Always type in four numbers. The load terminates
on the fourth number. Vou can check the preset number withour in-
crementing by typing SHIFT/b. This combination also loads the serial
number into any of the message memories.
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when the serial number is accessed via amessage memory, it increments
before transmitting. i.e., if you preset to 0000, the first number sent
via the message memory will be 1 (OOOX). If you have aproblem during the
contest with the numbers getting out of line, you can increment the
serial by typing CTRL—l or decrement by typing CTRL-D.
If the serial number gets too far out of line, use the preset
to get back on track. Note that the decrement command takes
afinite part of asecond to finish, the OVERFLUU lamp will iight during
the decrement as a reminder.
SETTING THE TIME:
If you have the real-time clock option, you will want to set the time
after you have turned on the unit. (The clock only runs when the unit
is powered, either by ac or 12 Vdc. Because this clock is not as
stable as a normal timepiece, it may gain or lose time even if
left powered.
To set the clock, type CTRL—7 and type in the time in 24 hour format
i.e. 7:00 PM is 19:00. Type the first three numbers starting with
the most significant ("1” in the case of 17:00, "O" in the case of
06:15, etc.) Type the fourth number at the 0 seconds time and the
clock will be exactly set. This means you will normally wait for the
next minute to come up before hitting the last number, Vou must always
type four numbers and the preset terminates automatically on the last
number.
To send the time over the air, type SHIFT/At(white ’'A"). You may prefix
and suffix aspace as if it were a single letter in the text, or a more
elegant way is to imbed it in amessage memory with the PST,EDT,EHT or
what have you plus the date. (TIME HR IS 12:45 PST -12/24/80) You embed
the time during the message load by simply typing SHIFT/A! (white “A").
USING THE FIXED MESSAGES:
There are four fixed messages in the KB-4900 which are coupled with
message memory "A". These are:
1. CH CD DE (message "A") Note that message "A" must be CALL LETTERS in these
messages. This message is called by typing SHIFT/Ct (white "C")
2. CD TEST DE (message "A"). Type SHIFT/D3
3. DE (message "A"). Type "ID" (Use SHIFT/XD for CH ID during RTTY operation.
4. DRZ (message "A") Type SHIFT/Bl (There is no "DE" in this message for
brevity.
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PRESETTING THE MESSAGE REPEAT DELAY:
You can repeat the message memories simply by striking the white message
key repeatedly or you can use the delay mode for delayed repeats of from
1 to 99 seconds. To load the delay figure in seconds, type CTRL-- (dash)
and then type two numbers representing the delay desired (in seconds). Type
the most significant number First (the TENS digit). If the number is less
than 10 you must type the leading zero. Now when one of the four message
memories are called up, it will repeat continuously at the interval preset
until aborted by hitting the SHIFT key while the delay is underway. The
DVERFLDN lamp lights during the delay period as a convenience.
DELETE FUNCTION:
Vou can delete the last WORD typed, assuming it hasn’t started transmission, by
hitting the "DELETE" key. SHIFT/RESETl(WHlTE KEY) has the same effect if you
prefer. Each time you hit the "DELETE" key, the last word (back to a"space"
will be deleted.
If you are loading the message memories, or setting the time or the serial; the
"DELETE" key will delete one CHARACTER per depression.
ABORT MESSAGE MEMDRV DR BUFFER TRANSMISSION:
Hit the white reset key and the message memory and buffer will be
reset. The message memory is saved but buffer contents are lost.
SVSTEH RESET would do the same thing but the mode would default to CM.
HDLD TRANSMISSION:
Transmission may be temporarily halted by typing SHIFT/SPACE. This allows
the receiving station to break for arepeat etc. You can use the paddle
during the hold if you like. The transmission will be continued when
you hit the "CTRL" key. This feature can be extremely useful in traffic
handling. The "HOLD" is effective in all modes using the sending buffer.
SYSTEH RESET:
when you turn on your KB—4900, the circuits are automatically reset
and the unit comes up in the Horse keyboard mode. The time and serial
registers plus the message memories will have garbage in them as their
contents ,by design, are not affected by areset. When power goes off,
their contents are of course lost.
Normally, the only time you have to operate the systee reset (except
For exit trom the code practice modes) is, if for some reason,
such as a power transient or severe r.f. interference,
the processor goes bananas. If this happens, the keyboard may
be locked, or sending the wrong keys or there may be astring of unwanted
characters transmitting. In any event, you will Feel you have lost control
of things. If this happens, hitting the SYSTEH RESET will make every-
thing right again. The time and serial may be scrambled depending how
the processor program self destructed during the crash. The program is
permanently locked in the EPROH so no permanent change will occur.
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OPERATION UN +12 VDC:
Your KBv48OO can be operated from +10 TD +14 Vdc batteries or from
amobile power system. You can also use a +12 Vdc battery continuously
connected for battery backup in case of ac power failure. With the
battery voltage at or below about 12 Vthere should be little drain
as long as the unit is powered by ac. Connect the battery cable to the
KB-4900 before applying power to the other end or you may get a
spectacular short if the center pin of the RCA plug hits the (grounded)
chassis! In any event, place an inline 1 Ampere fuse in the battery
supply line for safety.
You can reduce the battery current drain by half by removing the
meter illumination lamps.
CIRCUIT FUNCTIONS:
The KB—4900 consists of an 8035 microprocessor. a2732 32K bit EPRDH
for program storage and a2114 4K bit RAM for sending bufier and
message memory storage. An B044 is used for the keyer section.
A 74LSlb4 is used for the keyboard "X" matrix scan. Two 74LS75’s
are used to latch the EPRDM and RAM addresses. A74LS175 serves
to latch the lower four hits of port 2. Three lLD—74 dual optical
isolators isolate the paddle key, manual key and RTTY loop.
A 74LS3O B-input NAND gate is used to detect ahexadecimal OFFH on
the latched address lines. This is NORed with the write signal from
the processor to develop astrobe for writing to an external parallel
ASCII monitor.
If you have the real-time clock option. three HC1451B dual BCD counters
divide the 4OOkH2 ALE frequency to 0.4Hz. This signal, {ed to the B035
port 17, provides the clock reference.
CALIBRATION:
Normally, your KE—49OO will not need calibration over the life of the
unit however you may touch up the settings if you desire.
1. Haximum speed limit: This parameter is set by adjusting
atrimmer labled "R1" and located on the small PCB located
on the rear panel of the unit. It is the only trimmer on the
board and is accessable by simply removing the four screws
holding the bottom wrap-around. You can adjust the maximum
speed (when the speed pot is full clockwise) by rotating the
trimmer until the speed meter reads your desired maximum.
2. Speed meter calibration: A trimmer on the keyboard PCB controls the
calibration o! the metering circuit. Connect an oscilloscope or
pulse measuring counter to pin 14 of the 8044 IC. Set the speed
pot to give areading of 48 ms. for cycle length when the dot key (or
CTRL—8) is depressed (dot is 24 ms., space is 24 ms.). Then adjust
the trimmer marked “s” on the keyboard PCB. This trimmer is
accessible from the top or bottom of the board. hen the speed
meter reads 50 upm, the adjustment is correct. (You will NOT HEAR
dots during this test if you use CTRL-E. They are muted.)
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3. Buffer meter calibration: Another trimmer on the keyboard PCB controls
the buffer meter calibration. Press SHIFT/SPACE(bar) to place the
unit in apreload position. Then type keys at random until the buffer
fills and the DVERFLDN NARNING lamp lights. Hit three more
keys to completely fill the buffer, then adjust the trimmer marked
"b" on the keyboard PCB until the buffer meter indicates "I00". Press
the SYSTEM RESET to reset the unit. Note that this trimmer is also
accessible from the top or bottom of the PCB.
I bl CIKXESEE EJF7 I I F7F='I CZLJL_1'\’- -- - - - - - - _ - - _ _
Field trouble shooting is best accomplished by substitution of
IC‘s based on an educated guess of possibility. Or just blind
substitution if no localization can be made. The only component
not available in the field is the EPRDH which must be ordered from
the factory. The B044 may also be obtained from the Factory. D4 course,
any component may be ordered from us if desired.
If you can’t locate the problem, call or write us for help. we'll
suggest the best way to proceed, possibly requiring the return of the
unit.
L. IP4 I'TEEI) UJ€§F?F?£§hJ1'\(_ --------_ - - - - - - - - --
He will repair any defect caused by components or workmanship without
charge for labor or materials for aperiod of 90 days after you receive
the unit. You will be responsible for shipping both ways from our factory.
After 90 days, we can quote the estimated repair cost after examining the unit
according to prevailing wage and material costs. Although complicated in
Function, the KB—4900 is quite simple in execution so repairs should not
be too difficult. In addition, all lC’s are socketed for ease of servicing.
The one event which ruins alot of amateur equipment is the electrical storm.
This sometimes turns part of the circuitry into soot and invariably burns out
every semiconductor. If not too severe, we can sometimes repair the unit
at an acceptable cost. In any event, see if your homeowner’s insurance
covers such things so you can easier decide what you can bear. The best
insurance against electrical damage is to disconnect the ac power from the
station completely (Pull the main plug, don’t depend on the switch) and ground
and disconnect your antennae from your equipment.
F’F?(3(3F?¢§r4 C:F1£\PJC5EEE3 FNPJI) F?EE\J I 53 I CJPJES ------
The program in your KB-4900 is contained in an EPRGH. This device can
be erased with ultraeviolet light and reprogrammed quite easily. If we
make product updates of the program, we will correspond with you to ascertain
if you desire the update. If the update is acorrection o6 aproblem, the
only cost would normally be asmall mailing charge. If the update is
asigniicant improvement, there may be some reasonable charge depending
on the nature of the change. You may change the (socketed) EPRDH yourself
or if you don’t feel up to it, you can always have us do it. The only
difficulty is inserting the device into the 24 pin socket without mashing
the pins. Otherwise, it’s afive minute job.
CURTIS ELECTRD DEVICES, lnc., Box 4090, Mountain View, CA 94040
Tele: 415 494 7223 TNX: 910 373 2017 Cable: CURTIS, PALD ALTO, CA
Shipping address: 4140 Transport Ave., Palo Alto, California 94303
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