Originally published in the Lima
newsletter February 1991
THE 99/4 HOME COMPUTER:
by Charles Good - Lima Ohio User Group
A SHORT HISTORY OF THE TI HOME
TI began shipping the 99/4 (copyright 1979 on the color bar title
screen) in October 1979. It cost $1150 bundled with a 13 inch
color monitor (FORTUNE, December 3, 1979, p.54). Initially you
had to take the monitor and could not purchase the 99/4 separately, and
most purchasers had to pay close to full price. Bundling was
necessary because the 99/4 console passed but TIs TV modulator
initially failed to pass FCC lab tests for noninterference with radio
and TV broadcast reception. The modulator emitted too much RF
radiation (BUSINESS WEEK, March 19, 1979, p.37). However, at that
time the FCC did not regulate RF radiation from computing devices not
hooked directly to TVs. So TI got around the FCC regulations by
offering to the public a "complete package". It wasn't until
January 1, 1981 that the FCC began testing ALL computers likely to be
used in a home environment for TV/radio broadcast interference (POPULAR
COMPUTING, November 1981, p.6). TI eventually came up with a TV
mudulator that would pass FCC tests and on November 28, 1980 began
selling the console and monitor separately. The console's list
price was $650 (BUSINESS WEEK, December 8, 1980, p.28). This was
in one respect was actually a price increase, because the separate
prices of the console and monitor were $250 more than their previous
TI never published any sales data for the 99/4, but an independent
market research firm estimated that TI would sell 25000 between its
introduction and the end of 1980 (FORTUNE, June 16, 1980, p.139).
During the summer of 1981 TI quietly introduced the 99/4A with a list
price of $525. By the time production of the 99/4A ceased in late 1983
or early 1984 the store price for a brand new 99/4A was $50, and over 1
million, perhaps several million 99/4As had been sold.
SUMMARY OF DIFFERENCES BETWEEN THE
99/4 AND 99/4A.
The most obvious differences are the keyboard, the lack of lower case
letters on the "4", and the "4"s EQUATION CALCULATOR. Most "4"s
have an earphone jack on the front for private listening, but mine
doesn't. I will discuss most of these obvious differences in
detail. Other differences are listed in an accompanying article
by Mike Wright. The 4A gets its "A" from the fact that it has a
9918A video processor, whereas the 99/4 has a 9918 video
processor. The 9918A has bit map mode, which is not found on the
9918 processor. This means that any software that uses bit map
mode will not run on the 99/4. Other differences between the 99/4
and 99/4A (such as the "4"s lack of an XOP assembly directive) are
referenced in the index of the Editor/Assembler manual (p.456) under
the heading "Computer differences".
In general, all software written for the "4" will run on the 4A.
Some complicated routines on the 4A were required to achieve this
compatibility. The "4" has 256
bytes more free memory in TI BASIC than the 4A, so some BASIC software
written on a "4" may not work on an unexpanded 4A. Lots of
assembly or GPL software written for the 4A will NOT work on the "4",
and there is no easy way to upgrade a "4" to a 4A. The Mini
Memory module and its line by line assembler, and the E/A module and
its editor and assembler work OK on the "4". A partial list of
"won't work on the 99/4" software includes TI-Writer, Multiplan,
Funnelweb v4.x, the LINES program that comes with the Mini Memory
module, all the Milton Bradley game modules that were created to
accompany the MBX system, Word Invasion, Parsec, Story Machine,
Alpiner, Dragon Mix, and Word Radar. Most of these modules and
the LINES program are probably incompatible because they use bit map
mode. There are probably other reasons for the incompatibility of
Multiplan, TI-Writer, and Funnelweb. Even the non-editor parts of
Funnelweb won't work on the "4". When you boot Funnelweb into the
"4" using the extended basic module, the title screen shows blanks
where there should be lower case letters. You can then go to
Funnelweb's extended basic user list, but here the "4" locks up.
You can't boot any software from the XB user list.
THE KLUDGY 99/4 KEYBOARD
After playing around with my "4" for a couple of months, I am forced to
agree with the statement made in an accompanying FORTUNE magazine
article. The 99/4 is a real dog, mainly because of its keyboard.
There are 41 "chicklet" style keys, each slightly contoured and shaped
like a narrow rectangle. The 4A keyboard has 48 keys.
Although each 99/4 key depresses
separately, the keys are not what experienced users would call "full
travel" There is no tactile response, no click, before the keys
suddenly bottom out at the end of their downward travel.
Non-alphanumeric keys include one (and only one) SHIFT, an ENTER, a
SPACE bar, and a SPACE key immediately to the left of the "A"
key. Alpha keys always produce upper case letters, so the SHIFT
key is not used as often as it is on the 99/4A. There is are no
ALPHA LOCK, FCTN, or CTRL keys on the "4". The "4"s SPACE key and
bar do exactly the same thing, leave a blank space. I can see no
reason at all for this space KEY, in addition to the normally
positioned space bar. There are ASCII characters built into the
99/4 console that are not implemented on its limited keyboard, yet
there is this stupid extra space key.
Touch typing on the 99/4 is difficult. The keys are spread apart
the same distance as on the familiar 99/4A keyboard, so it is possible
to get all your fingers at once onto the keys. But the small
vertical size of the keys and their lack of tactile feel makes touch
typing difficult. The small size and minimal contour of the "4"s keys
makes it difficult for a touch typist to find by feel and seat his or
her fingers in the center of the desired keys as the fingers move
blindly around the keyboard. The fully contoured much larger keys
of the 4A (larger because there is less space between keys) makes touch
typing much easier. A special problem to experienced touch
typists is the lack of any key to the right of the "L". This
means there is no "home" key for the little finger of the right hand to
touch, and this will drive most touch typists crazy. Frequently,
when I try to type on my "4" I end up accidently moving my fingers over
one key to the left on the home key row so that all ten
fingers have something to touch. My left hand pinky finger is
then on the useless SPACE key instead of on the "A" where it should
be. Then I type rtow fevfw. TI recognized this
problem. The only application software written for the 99/A that
is likely to require touch typing, the Terminal Emulator II, has a
keyboard overlay with a raised area creating a fake key for the right
hand's little finger.
TI provided a series of overlays specifically for use with the 99/4 and
not usable with the 4A. Some overlays were packaged with the "4"
and others were available with specific command modules. Because
of the narrow vertical size of each key there is enough room between
rows of keys on the "4" to display a text prompt immediately above ANY
key, not just above the numeric keys as is the case with the 4A.
The overlays have text prompts for special keypresses, and cover the
entire "4" keyboard, with the keys sticking up through holes in the
overlay. Special keypress usually involve using the SHIFT key in
combination with a letter key. One overlay packaged with the "4" shows
the editing keys used in BASIC. SHIFT/Q=quit.
SHIFT/W=begin. SHIFT/ESDX= arrows. SHIFT/R=redo. SHIFT/T=erase.
SHIFT/A=aid. SHIFT/F=delete. SHIFT/G=insert.
SHIFT/Z=back. SHIFT/C=clear. SHIFT/V=proceed. There
is nothing intuitive about some of these keypresses (why not SHIFT/B
instead of /Z for back), so the overlay is really needed. Another
overlay packaged with the "4" shows the split keyboard keys that can be
used with some games to simulate the 8 positions of joysticks #1 and
#2. In addition to the overlays packaged with the computer, I
have seen overlays designed for use with the following command modules:
Terminal emulator I, Terminal emulator II, Video graphs (PHM3005), and
Video Chess. There may be other overlays I havn't seen.
One of the reasons I give the 99/4 my "real dog" rating is the
uncontrollable multiple repeat of the keys on my "4"s keyboard.
This makes it almost impossible to do any useful typing, touch or hunt
and peck, on my "4". Autorepeat of all keys at rate of 12
characters per second after a 1 second delay is listed as a NEW feature
of the 99/4A (99ER MAGAZINE, Vol 1 #2, July/August 1981, p.48).
Autorepeat is NOT described in TI literature as a feature of the
"4". On my "4" any of the keys are likely to repeat
INSTANTLY. When you depress a "4" key, the keypress registers in
the memory of the computer at a point about 1/2 way down the travel of
the key. There is no tactile response that this has
occured. The only thing your finger feels during a keypress is
the sudden stop when the key bottoms out. If the key hovers in
this "1/2 way down" region you get mmmultiiiplle displays of theee
keeey on the scrrreennn. Try as I might, I can't seem to avoid
this. My "4"s keyboard is very sensitive. Other experienced
4A users who have tried my "4" all have the same problem. Having
to use backspace (SHIFT/S) and delete (SHIFT/F) after every 6-10
keystrokes gets old really fast. It has been suggested to me that
this problem may be related to the ageing of my "4". The
condition may not have existed when my "4" was built. One
collector of TI computer products told me, "I had a 99/4 that did
that. I got rid of it and replaced it with a 99/4 that still
ONLY UPPER CASE LETTERS
No keypress on the "4" keyboard will give ASCII codes 97-122, the lower
case letters. Everything you type is in upper case, and this
means you only use the SHIFT key in routine typing to shift the numeric
keys and display !@@#$%^&&*(). The 99/4 uses a 5x6
pixel grid to display upper case letters. The 99/4A uses a 5x7
grid to display both upper case and lower case text. If you load
into the "4" BASIC software written on a 4A that includes lower case
text, the program seems to work OK, but no lowercase letters are
displayed on screen.
THE EQUATION CALCULATOR
When you PRESS ANY KEY TO CONTINUE from the color bar powerup screen of
the "4", you get a menu with three choices. Press 1 for TI BASIC,
2 for EQUATION CALCULATOR, 3 for TITLE OF COMMAND MODULE.
The EQUATION CALCULATOR is a way of using the "4" in mathematical
calculations without having to write a BASIC program to do the
calculations. You can do simple arithmetic, and you can also use
exponential numbers, PI, SQR, exponents, SIN, COS, TAN, and ATN in your
calculations. Everything that can be done using EQUIATION CALCULATOR
can also be done using a TI BASIC program, or directly from BASIC
The EQUATION CALCULATOR screen is divided into three sections.
The bottom section is where you do your calculating. You can, for
example, type in a simple calculation such as 1567+56.98-145+(12/98),
press <enter>, and display the answer. To do the same thing
in BASIC command mode, you would have to type PRINT before you typed
the numbers of the calculation. A single calculation is limited
to 28 characters (one line of text).
You can define variables such as LENGTH=60, press the up arrow, and
have this variable stored in memory and permanently displayed in the
upper third of the EQUATION CALCULATOR screen. You can display up
to 6 variable names and their current values on screen in this way and
not have to worry about the display scrolling off the top of the
screen. You can do the same thing in BASIC command mode by
pressing <enter> after typing LENGTH=60. The value of
LENGTH would be stored in the computer's memory, but it would only
remain on screen until it scrolled off the top due to subsequent
You can also define an equation such as PERIMETER=2*LENGTH+2*WIDTH and
store this equation in the middle part of the EQUATION CALCULATOR
screen. You can then define the values of the variables LENGTH
and WIDTH, use the down arrow to bring the equation into the bottom
work area of the EQUATION CALCULATOR screen, press <enter> and
display the current value of PERIMETER. You can then redefine
LENGTH and/or WIDTH, and reuse the equation to calculate the new value
of PERIMETER. You can also store equations for repeated use in a
BASIC program, although you cannot store such an equation in memory in
BASIC command mode. In command mode you would have to retype the
equation each time.
I don't think EQUATION CALCULATOR is very useful. Apparently TI
didn't either, because they dropped it when the 4A was released.
From BASIC (a program or from command mode) you can do all the same
things, and more. The main limitation of EQUATION CALCULATOR is
the 28 character size of a formula or chain calculation. The most
common routine calculating I do on my 99/4A is to balance my
checkbook. I enter BASIC command mode and type PRINT, followed by
my initial bank balance, followed by all my subsequent withdrawals (as
minus numbers) and deposits (as positive numbers). Before I press
<enter> to display my balance I can check the screen to see that
all the numbers in the calculation are typed correctly and use INSERT
or DELETE to correct mistakes. Such a long chain calculation
requires several lines on the screen to display all the digits before
pressing <enter>. TI BASIC command mode gives me 4 lines.
EXTENDED BASIC command mode gives me 5 lines. EQUATION CALCULATOR
allows me only one line of digits.
When it was released in 1979 the 99/4 was the only consumer device that
could really be called a "Home Computer". It was the first to
utilize cartridge software. Its speech synthesis was, and still is,
unequaled. It was easy to use, easy to program in BASIC, and it
was powerful. Its high price was probably the major reason for its
initially limited sales. Its rotten keyboard didn't help
either. I'm sure glad we now have the 99/4A. The 4A
is much superior to the "4".