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Differences between the 99/4 and 99/4A

Between the TI 99/4 and the TI 99/4A were some striking and less striking differences:

- The keyboard of the 4A was better and greater. De 4 had keys like those of a calculator. The most striking difference are the orange ENTER- and SHIFT-keys on the 4.

- The smaller number of keys on the 4 could lead to some risky situations. For instance, the 4 didn't have a FUNC-key. A program could be stopped with SHIFT-C. Who instead of that pressed SHIFT-Q, lost everything, because this was the fatal reset combination.

- On the 4, you could only type in capitals.

- Unlike the 4A, the 4 had overlays that covered the whole keyboard.

- In the start menu the 4 had an extra option: the calculator function. This explains why the 4 had 5 KB more ROM.

- The 4 had a different graphic chip, with an extra mode, although one could not use it in BASIC.

- The adapters were different - never confuse them!





Welcome to the nostalgic history of home and game computers  

TI's short-lived adventure

The Texas Instruments 99/4A changed my life. It was the first home computer I came in touch with in the early eighties, through a friend from high school. With admiration I followed the piece of magic he performed with this machine; I'd never seen anything like that before. Most amazing was the moment when this computer started to talk through a Speech Synthesizer and when even more mysterious things happened through the modem, a device in which one had to put the receiver.

For me it was the beginning of an addiction to countless games like TI Invaders, but also the beginning of a long exploration of all the possibilities of BASIC.

The Texas Instruments 99/4A was the successor of the TI 99/4, which because of it's late introduction in Europe only led a short life there. The case was just as elegant as that of the 99/4 - aluminium and black plastic - but some aspects were improved. The 99/4a had a mature keyboard, a major improvement compared with the (only) 41 calculator-like keys of the 99/4. More differences between the two computers are described in the box elsewhere on this page.

Competitors Afraid
When Texas Instruments announced in 1979 that it would launch it's own home computer, competitors like Apple and Commodore shuddered. That was understandable, even more when it turned out that the TI 99/4 and the 99/4A would be the first home computers with a 16 bits processor. Its name was the TMS 9900, manufactured by Texas Instruments since 1976.

In other respects these home computers also showed great promise. For instance, they were equipped with an excellent graphic chip, known from the Colecovision and of course also manufactured by Texas Instruments. This chip conjured up sixteen colours on the screen and made it possible to use sprites. 

The TI 99/4 and 99/4A had a cartridge slot that simply asked to be used. A tape recorder in combination with these computers, somehow or other was 'not done'. Texas Instruments and some other companies produced dozens of different cartridges, varying from games to administrative programs.

Soon many options were available, all manufactured by Texas Instruments. People who had plenty of dough - the prices were substantial - could equip there home computers with an external floppy drive, and acoustic modem, a thermal printer and the famous Speech Synthesizer. This thing with its canned voice produced much hilarity, I remember.

When you had all those options, you had a snake of devices connected to your computer. Texas Instruments was aware of this problem and started to sell in 1982 the so-called Peripheral Expansion Box. This box was equipped with a floppy drive and a memory extension and had besides that six slots to hide other options in an orderly way. With this large box you had almost a real PC at home.
Very slow
In spite of all this it went wrong with the TI 99/4A; competitors could heave a sigh of relief. I don't know if it played a role in the failure of the home computer adventure of Texas Instruments, but one of the problems was the incredible slowness with which BASIC programs functioned on the TI 99/4 and 4A. This was caused by the fact that BASIC was double interpreted - and thus the advantages of the fast processor were nullified. Programs in machine code, like on the cartridges, didn't have this problem and functioned as one should expect on this kind of computers.

What anyhow caused problems for Texas Instruments was the fact that it kept the technical details of the TI 99/4 and 4A secret. Therefore competitor couldn't profit with own games and options. But the other side of the coin was that for the TI there was less choice in options and games then for other home computers.

Beige model
Besides, Texas Instruments initially asked a substantially prices for the computers, and the options were also expensive. Soon a price ware flared up with Commodore and other companies. Texas Instruments tried to survive on the home computer market with a beige model of the TI 99/4A that was cheaper to manufacture, but it was of no avail. Finally TI went below the cost price, and the company was in the red.

TI was through with it
At the end of 1983 Texas Instruments decided to quit the home computer market. Then, some 2.5 million 4A computers were sold. It is to its credit that Texas Instruments during a long time maintained the service for owners of its home computers.

Specifications of the Texas Instruments TI 99/4A

Manufacturer Texas Instruments
Period 1981 - 1984
Frequency 3,3 MHz
RAM 16,25 KB 
Text mode 32 x 24 (16 colours), 40 x 24 (2 colours)
Graphic mode 256 x 192
Colours 16
Sound 3 channels, 5 octaves, 1 noise
I/O monitor, cassette, cartridge, 2x joystick, extension port
Price 525 U.S. dollar

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History of Home and Game Computers, by Erik Klooster, the Netherlands

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