The TI-74 "BASICALC": A Modern 8K Pocket Sized Reincarnation Of The CC40 And 99/4A



TI-74 Links
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-Great resource. Download TI-74 docs.
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Thanks to Charles Good for donating this article.

reviewed by Charles Good 
Lima Ohio User Group 
April 1992
Why did TI suspend further HexBus product development and
stop selling the CC40 in late 1984 less than two years after
the CC40 introduction in January 1983?  No, it probably
wasn't because TI's non release of the "didn't work very
well" Wafertape Digital Tape Drive left the CC40 without any
means of mass storage.  TI had that problem solved with the
CC40+ which had a built in reliable cassette interface.  But
the CC40+ was never released.  Why?  A probable answer to
these questions is that TI had something better up its
sleeve.   In 1985 TI began selling the TI-74, a downsized
improved version of the CC40 with an optional cassette
interface.  In 1992 these products are still available.  
The TI-74 is "modern" in the sense that TI still actively
sells the product through dealers.  Although first released
in 1985, my TI-74 user guides have a 1990 copyright
indicating TI's continuing support of the machine.  The
TI-74 is a "reincarnation" of the CC40 and 99/4A in the
sense that its BASIC is very similar to TI Extended BASIC
for the /4A and almost identical to the BASIC used in the
CC40.  Anyone familiar with Extended BASIC on the /4A will
have no trouble programmg the TI-74.  The similarities
between the 99/4A and the TI-74 are so profound that both
the Lima Ohio user group and the Swedish user group have
members who own a TI-74 and DO NOT own a 99/4A.  I have
typed in several games and application programs written for
the 99/4A into my TI-74 with very little modification.
Finally the TI-74 can be considered a "pocket" computer
because it measures only about 4x8x1 inches.  You can carry
the thing around in your shirt pocket if you don't mind
having half the computer sticking out beyond top of the
The TI-74 can best be described as a reduced sized CC40 with
more memory, a greatly enhanced set of scientific calculator
functions, and a slightly reduced suite BASIC commands
compared to the CC40.  The keyboard layout of the TI-74 is
very similar to that of the CC40.  Anyone familiar with the
key combinations of the CC40 will find the same keys,
usually in the same place on the keyboard, do the same
things on the TI-74.  Typing FRE(0) on the TI-74 shows 7710
bytes of program space available for BASIC programs.  On the
unenhanced 6K CC40 a FRE(0) shows 5730 bytes available to
The TI-74 is powered by 4 AAA batteries or an optional AC
transformer.  Most memory contents are preserved when the
computer is "OFF".  Although TI makes no clains about how
long the batteries should last, my experience suggests
several tens of hours of "ON" time on a single set of
batteries and many more hours of "computer is OFF" time.
Unlike many "modern" laptop and palmtop computers, the TI-74
does not have battery eating features such as a backlit
display screen or a built in hard drive.  Like the CC40 the
TI-74 has an LCD display that shows 31 5x7 pixel characters
of an 80 character line.  You can scroll or window
left/right with arrow keys and can use the up/down arrow
keys to display adjacent lines.  A contrast adjustment
allows viewing in most lighting situations. 
The keyboard has slightly concave rectangular (chicklet
style) keys which provide a definite tactile response when a
keypress is detected.  Keys are arranged in a manner
similar to, but not identical with, the CC40 keyboard.  The
alphanumeric keys are arranged typewriter style with a large
 key and (unlike the CC40) a shift key on BOTH sides
of the space bar.  Cursor and other special purpose keys
(FN CT Mode Break Run) are lined up in a row above the
letter keys where one usually expects to find number keys.
The number keys form a numeric keypad to the right of the
letter keys along with large ON and OFF keys.  Most keys
have at least two functions and many have more.  For example,
the letter keys all have specific calculator functions in
CALC mode and in BASIC mode these same letter keys can be
used to display on screen most BASIC commands with just two
keypresses.  Keys are closer together than on the CC40 so
touch typing is not possible.  However two finger typing is
fairly easy.  I am composing the first draft of this article
on my TI-74. 
Pressing the MODE key while in BASIC command mode switches
the TI-74 to calculator mode.  A total of 70 "scientific
calculator" functions are available by entering a number and
then pressing one or two keys to perform some action on the
number.  CALC functions include linear regression,
permutations, regular and hyperbolic trig functions, a full
range of statistics, and much more.  One interesting CALC
function allows you to enter angles in degrees as
degrees-minutes-seconds and have this converted to
degrees+decimals.  Factorials up to 83 can be calculated by
just entering a whole number and then pressing the "n!" key.
An INV(erse) key will reverse the effect of most CALC
functions.  For example pressing INV and TAN will yield the
ARCTAN of the displayed number. 
Mathematical display and accuracy are identical to that of
the 99/4A and the CC40.  Ten digits are displayed on screen
with internal calculations carried to 13 or 14 digits.
Large and very small numbers are displayed in scientific
As an educator, one feature of CALC mode I particularly
appreciate is STAT mode.  I can enter a long list of student
test scores and then obtain statistical information such as
the median and standard deviation of these data.  Other
statistics available once you enter a set of numbers (data)
include sum, sum of squares, number of data entries,
regression, line intercept and slope, and correlation
coefficient.  Stastical data can be entered as single data
values (as I do for student grades) or paired values (such
as plots on a two dimensional graph). 
BASIC programs as well as text assigned to "hot keys" (up to
10 hot keys each of which will recall from memory up to 80
characters of text and/or mathematical formulas) remain in
memory when in CALC mode and can be immediately recalled by
pressing the MODE button to enter BASIC mode.  Stastical
data remain in memory when you switch from CALC to BASIC
mode and can later be accessed by going back to CALC.  When
you turn the computer "OFF" and later turn it "ON" you are
returned to the mode you left when you pressed "OFF".
Memory contents (BASIC programs, the contents of "hot keys",
and stastical data) are all preserved when the computer is
Except for lacking commands for user defined graphics,
speech, color, sprites, and sound, TI-74 BASIC is very
similar to TI Extended BASIC on the 99/4A.  Keeping in mind
the limited screen display of the TI-74, 99/4A users should
have no trouble programming the TI-74.  Although TI-74 BASIC
has a few fewer functions than CC40 BASIC the differences
between the two are minor.  Most CC40 BASIC software
listings can be typed into the TI-74 with no modifications
at all and will run with no problems. 
The following functions in CC40 BASIC are not available on
the TI-74: 
-- BEEP (Used in the CC40 with DISPLAT AT.  There is no
sound at all available on the TI-74). 
-- ATTACH and RELEASE (A feature of CC40 subprograms I have
never actually actually seen used). 
-- CALL CHAR (There are no user definable display
-- CALL INDIC (No user definable display indicators are
-- CALL SETLANG (No alternative languages for text prompts.
All built in text prompts in the TI-74 and its software
modules are in English). 
-- CALL VERSION (The version of BASIC is identical on all
-- CALL CLEANUP (Instead you can remove from memory
variables not being used in the current program by SAVEing
to a non existant device). 
-- There is no direct access to assembly language except for
CALL IO on the TI-74.  Therefore the following CALL's of
CC40 BASIC are not available on the TI-74; GETMEM POKE PEEK
The only important CC40 BASIC software I have that can't be
modified to work with the TI-74 are "DIR" programs designed
to read the directories of mass storage devices such as the
Wafertape drive and Quickdisk drive.  These programs are
very useful because they give you the exact spelling of
program and data file names.  You need the exact spelling to
load from these devices.  The directory reading software
uses assembly CALL's not available on the TI-74.  The only
other important assembly CALL known to me on the CC40 is a
CALL EXEC(xxxx) to deactivate the battery saving automatic
power down.  The same thing can be done on the TI-74 by a
specific sequence of keypresses. 
Standard equipment that comes with the TI-74 includes two
book length guides, a set of alkaline batteries, a plastic
hard case, and a quick reference card that fits into the
inside of the hard case's hinged lid.  I really like the
hard case and keep my TI-74 in the case most of the time,
even when I am actively using the computer as I am now to
enter the text of this article.  The case is very tough and
prevents accidental keypresses.  The increased size of the
TI-74 plus case does, however, make it more difficult to
keep the computer in one's shirt pocket.  If you open the
case lid all the way you can lean the TI-74 against a small
object at a convenient viewing/typing angle and position the
case lid over the object's top for stability.  Right now as
I type this article I have my TI-74 resting against an
A cartridge port to the right of the display accepts a solid
state software or RAM cartridge.  Available software
these software cartridges are almost identical to cartridges
of the same name sold for the CC40 and the TI-95
programmable calculator.  When I sent in my TI-74
registration card to TI, I received back a large color
brochure describing TI's custom module service for industry.
For about $100 per module TI offers to manufacture (burn
eproms for) custom TI-74 software modules taylored to a
customer's specifications.  Specific examples of some custom
modules are described in the brochure. 
For me the most useful TI-74 module is the battery backed 8K
RAM.  A similar module exists for the CC40.  You can save an
"image" of the TI-74's memory into the module, remove the
module, and later reinsert the 8K RAM and load its contents
back into the TI-74.  Used this way the 8K RAM serves as a
mass storage device.  You can also leave the RAM module in
the TI-74 and exchange the contents of the computer's memory
for what is stored in the module.  You can thus keep two
different BASIC programs in the computer at the same time,
one in the RAM module and one in the computer's memory,
switching back and forth between the two. This memory
flip-flop trick is something you can't do with a CC40.  You
can also use the 8K RAM as additional CPU memory by invoking
CALL ADDMEM.  This makes about 15700 bytes of memory
available in BASIC instead of the the TI-74's normal 7710
The TI-74 has a 10 pin peripheral connector TI calls the
Dock Bus.  Available TI peripherals that fit this connector
include an AC adapter adapter (the "adapter adapter" plugs
into the TI-74 and TI's AC9201 AC adapter plugs into the
"adapter adapter"), a battery powered thermal printer, a
cassette tape recorder interface, and an MS-DOS computer
interface.  I don't yet own any of these peripherals, so the
descriptions below are based on information published by TI
and on articles that have appeared in past issues of TI PCC
The PC-324 THERMAL PRINTER is set up as device #12 and uses
an unusual size thermal paper roll.  You can either purchase
FAX paper and cut it to size with a hacksaw or pay $5 at a
dealer for a 3 roll pack of "official" paper.  Sort of
reminds you of the paper "problem" with the 99/4's Thermal
Printer (TP)! The small PC-324 printer is about the same
length and width as the TI-74.  It runs on batteries or an
optional AC adapter.  Text is only 24 columns.  There is
only one text font and there are no dot addressable
graphics.  From CALC mode you can use the PRINT key at any
time to print the screen display.  From BASIC mode you can
LIST programs or OPEN the printer in a program or from
command mode and print whatever you want. 
The CI-7 CASSETTE INTERFACE CABLE allows you to use most
cassette audio recorders, even those that use mineature
cassettes, to save BASIC programs or data files to tape.  It
appears to work the same way as the cassette interface of
the never released CC40 PLUS.  Its operation also resembles
that of the Wafertape drive.  You can save several files
sequentially on the same tape each with a different file
name.  If you don't know the exact starting position of a
particular file the TI-74 can search the tape from the
beginning for a particular file name and when found load
that file.  The TI-74 can also be programmed to load the
next file found on the tape irrespective of file name.
Screen prompts are available telling the operator to press
the recorder's PLAY, RECORD, and STOP buttons and the
computer automatically senses the beginning and end of the
requested file.  You cannot use the CI-7 to save programs
from a CC40.  Many have tried and failed to do this.
Apparently the TI-74 contains within it specific code needed
to operate the CI-7 cassette interface, code which is
lacking in the CC40. 
The PC INTERFACE CABLE connects between the Dock Bus and the
25 pin parallel port of an MS-DOS computer.  With this cable
you can use the TI-74 to directly control the MS-DOS
computer via several device numbers.  Addressing device 14
lets you print using a parallel printer connected to the PC.
Device 45 lets you direct output from the TI-74 to the PC's
monitor for a nice 80 column multi line display.  You can
save or load TI-74 programs to and from the PC's disk drives
by referencing device 100.  Text in ASCII format can be
saved to the PC's drives with device 101.  If you own an
MS-DOS computer this cable would seem to be a very useful
TI-74 peripheral.  Can it be used with the CC40? I don't
know, but someone should find out.  The PC interface may be
the mass storage solution for CC40 owners who cannot get
obtain a Quickdisk or Wafertape drive. 
Superficially the 10 pin Dock Bus looks quite different from
the 8 pin HexBus.  However, as first noted in 1990 in
articles published in TI PCC NOTES and later in an article
by Dan Eicher in the March 1992 issue of the Lima User Group
newsletter, the Dock Bus and HexBus are electronically
identical.  Two extra Dock Bus lines not found in the HexBus
that allow an external 6 volt source to power the computer
or peripheral through the bus.  By connecting the proper
wires of a HexBus cable to corresponding wires of a Dock Bus
If you don't want to make your own cable you can buy one
from L.L. Conner for $15.  Plug one end of the Conner cable
into the TI-74's Dock Bus and attach a HexBus cable to the
other end.  With this HexBus/Dock Bus cable I have used my
TI-74 with the following HexBus peripherals: RS232, Printer
80, Printer Plotter, Wafertape Drive, and Quickdisk drive. 
I much prefer to my use Printer 80 with my TI-74 rather than
the 24 column PC324 printer.  Like the PC324 the Printer 80
can be run on batteries or an AC adapter.  Unlike the small
hard to find expensive rolls of thermal paper used by the
PC324, the Printer 80 uses easily obtainable FAX paper rolls
or with a Thermal Ribbon obtainable from Sears or by mail
from TI regular sheets of typing paper. 
With my TI-74 I can OLD SAVE and OPEN files to and from my
Quickdisk (device 8) with no problems at all.  This is in
spite of the fact that I have the HexBus rather than the
Dock Bus version of the Quickdisk drive.  All I need is the
HexBus/Dock Bus interface cable made by L.L. Conner.  I know
of someone who uses a Dock Bus Quickdisk drive with his CC40
also with no problems.  The few CC40 applications written
for the Wafertape drive assume this device is configured as
device #1.  That's how I have always used my Wafertape Drive
with my own CC40.  It is fortunate that the tape drive can
be switched to other device numbers because I can't
successfully use my Wafertape drive as device 1 with the
TI-74.  The TI-74 expects the CI-7 cassette interface to be
device 1.  If I switch my Wafertape drive to some other
device number (I use device 2) then I can OLD SAVE and OPEN
files to and from wafertapes with my TI-74. 
I knew when I bought my TI-74 that the syntax of TI-74 BASIC
is almost identical to that of CC40 BASIC.  I now know that
the similarities between the BASICs of these two devices are
more profound.  Any BASIC program written on a CC40 and
saved to Quickdisk or Wafertape will successfully OLD into
the TI-74 and if the program doesn't use any of the BASIC
functions unique to the CC40 will RUN in the TI-74.  Almost
my entire library of CC40 BASIC programs stored on disk or
wafertape will load RUN out of my TI-74! The two computers
use similar 8 bit central processor chips (TMS70C20 for the
CC40 and TMS70C46 for the TI-74) that use the same assembly
instruction sets and BASIC token codes. 
The only reason for using for using small "notebook" or
"palmtop" computers such as the CC40 or TI-74 is portability
and/or ease of operation.  The additional memory and better
displays of desktop computers mean that in general desktops
are more powerful.  Software is available for desktops that
can accomplish anything that can be done with ROM cartridge
or BASIC software available for the CC40 and TI-74.  There
is a lot to be said for portability! The ability to carry
the CC40 or TI-74 around with you and use them anywhere (a
classroom the office on a camping trip etc) is the raison
d'etre of these small computers.  Unlike "modern" laptop
computers whose batteries usually last less than 4 hours per
charge these small TI machines last tens or a couple of
hundred hours of on time on a set of batteries.  For use in
the field the TI-74 and CC40 and their battery operated
peripherals offer lots of convenience.  For example, I am
typing this article while I lay in bed proped against a
couple of pillows.  A few minutes ago I made a phone call
from the phone by my bed that required me to look up the
phone number.  I have my name/address/phone data base stored
in my TI-74's 8K RAM cartridge, so I did a CALL GET(-1) to
store this article in the RAM cartridge and at the same time
put my data base in the TI-74's memory.  I looked up the
number and made the call.  Then I did another CALL GET(-1)
to bring back my document into memory and put my data base
back into the RAM cartridge. 
--1-Its CHEAPER.  You can get one used for $55.  Used TI-74s
are hard to find and a new one costs $100. 
--2-CC40 BASIC is a bit more powerful. 
--3-The KEYBOARD is physically larger and thus according to
some people easier to type on than the keyboard of the
--4-There is an assembly language word processing cartridge
called MEMO PROCESSOR available from TI for the CC40.  No
commercial word processing software is available for the
TI-74.  I am using a BASIC word processor program I wrote
myself to enter this article into my TI-74.  MEMO PROCESSOR
is much better than my BASIC word processor. 
--1-CALC MODE.  Scientists, engineers, and educators will
appreciate the rapid availability of 70 scientific and
statistical functions on the TI-74.  The same sorts of
calculations can be done in BASIC with the CC40 (and the
TI-74) by putting formulas into BASIC programs, but doing
the math directly from the keyboard is much easier and
--2-More user memory is available on the TI-74 than you get
in an unexpanded CC40. 
-- 3-Physical size.  The CC40 is just a little too big to
get your hand around and is slightly awkward to carry around
or hold in one hand.  No matter how you carry the CC40 it
seems the keyboard overlays are about to fall off and your
gripping fingers have trouble finding a place where they
don't press some keys. In my opinion the TI-74 is much
easier to handle.  You can easily and grasp the TI-74
with the fingers of one hand.  The hard case prevents
dust accumulation, accidental keypresses, and the
accidental loss of the quick reference card (or the LEARN
PASCAL keyboard overlay).  I feel very comfortable about
carrying my TI-74 around with me in my hand, in my briefcase,
or in my coat or shirt pocket just about everywhere I go.
Personally I have no more difficulty typing on the TI-74
keyboard than I do on the CC40.  In both cases two finger
"must keep looking at the keyboard" is my technique.  Touch
typing is not really possible on either machine. 
--4-The DOCK BUS is physically superior to the HexBus.
Although the two bus designs are electronically identical
the HexBus is structurally flimsy.  When inserting a HexBus
I/O cable into the bus on a CC40 or HexBus peripheral it is
hard to seat the cable properly.  There is lots of "play" in
the HexBus opening and it is possible to bend some pins
in the bus as you fool around with inserting the I/O cable.
The HexBus cables themselves are flimsy.  They are very
flexible and it is difficult to avoid pulling on the cable
rather than the small rigid cable end piece when removing an
I/O cable from the HexBus.  The DockBus and its I/O cables
are more substantial.  Cables fit snugly into the bus with
no free play and little likelyhood of bending a bus pin.
The cables are stiffer than HexBus cables and have large
easy to grasp ends.  Physically the DockBus and its cables
seem more substantial and thus probably more reliable than
the HexBus. 
The capabilities of the CC40 and TI-74 are similar.  The
TI-74 is a better math calculator.  The CC40 has a better
word processor but both can be used as calculators or text
processors.  Because of the memory flip-flop capability of
the 8K RAM and for physical reasons I prefer the TI-74. 
     Available by credit card directly from TI at
   --HX1010 Printer 80, the 80 column HexBus printer, $70 
   --CI-7 Cassette interface $35 
   --PC324 Thermal printer $60 
   --Technical manual $5 
   --8K constant RAM cartridge $50 
   --Learn Pascal, Stastics, Mathematics, Finance, Chemical
Engineering software cartridges $50 each 
   --TP324 thermal paper and PC Interface cable also
probably available directly from TI, prices unknown. 
     Available from EDUCALC at 800-677-7001 or (credit card
orders only 24 hours) 800-535-9650 
   --TI74 (the topic of this article) $99.95 
   --Statistics, chemical engineering, finance cartridges
$39.95 each. 
   --8K constant RAM cartridge $39.95 
   --PC324 Thermal printer $89.95 
   --TP324 paper for printer $4.95 
   --CI-7Cassette interface $26.95 
   --PA201 AC interface for TI74 (the "adaptor adaptor",
uses adaptor below) $6.95 
   --AC9201 adaptor to power printer and/or TI94 $16.95 
   --PC interface cable, allows storage of TI74 software on
PC disks and use of PC screen controlled by TI74 $54.95 
Available from L.L.^Conner Enterprise 1521 Ferry St.
LaFayette IN 47904, phone 317-742-8146 
--Custom cable to connect HexBus peripherals to the TI-74s
DockBus, a special order item, $20 
--Custom cable to connect HexBus RS232 to TI99/4A RS232
card, a special order item, $20. 
--Various HexBus peripherals.  Call for availability. 
Available from T.A.P.E. 1439 Solano Place, Ontario
California 91764, phone 714-989-9906 
--Quickdisk disk drives, either the DockBus version or the
HexBus version (with the L.L.^Conner cable) will work with
the TI-74. 
Jim Lesher, 722 Huntley, Dallas Texas 75214, phone
--nice selection of HexBus peripherals 

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