Texas Instruments 99/4A Computer

My uncle bought this computer, used it for a while, then gave it to my family when I was in high school (I think). It was our very first computer.
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“This is THE Home Computer”

I have a copy of a 20-page Texas Instruments brochure (CL435C) made in 1982. I have high-resolution scans of the pages, but I’m only posting thumbnail versions here. A low-resolution file in portable document format is available here.
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Adventure in Oz

oz01 oz02
I was able to find a copy of the program I mentioned in an earlier blog post at The Old Computer.  (See the zip file Adventure in Oz.  For some reason, the actual TI Extended BASIC file is called LOAD instead of OZ.)  It was apparently typed in by someone named Suzanne Nomina, and I had to go over all the lines in the programs and correct the typographical errors in them.

oz03 oz04
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Preparing for an Adventure in Oz

TIEB The second program I’m entering on Classic99 is also the first in TI Extended Basic.  (The picture on the left shows the book that apparently comes with the TI Extended Basic Command Module.)

It’s called Adventure in Oz.  It’s the longest program in the book Programs for the TI Home Computer by Steve Davis.  It’s composed of four programs:  the main one has 320 multiple-statement lines, two other programs create two data files, and the last one is a TI Basic music-playing program called Rainbow.

By default, the TI-99/4A had 16 KB of RAM (also called VDP (Video Display Processor) RAM).  Adventure in Oz requires the Memory Expansion unit (32 KB of RAM, but with only 24 KB available to TI Extended Basic programs).  The main program listing and the values of the numeric variables are stored in the Memory Expansion, and the values of string variables (in the two data files) are stored in VDP RAM.


The book says that the adventure game requires TI Extended Basic, the Memory Expansion unit, and a floppy disk drive. It fails to mention that the game also requires the Speech Synthesizer module.

So far, I’ve input enough code to show the title page.  When I have more time, I’ll type in the rest of the program.  I’ll blog about it when I’ve finished.


davisThe first TI BASIC program that I entered on Classic99 is CHAOS.  I got its listing from the book Programs for the TI Home Computer by Steve Davis (Dallas, TX:  Steve Davis Publishing, 1983).

There is a minor typo in line 370.  In the book, the two colons are not separated by a space.  The program with the typo seems to work correctly when run in TI Extended BASIC but causes an error when run in TI BASIC.  Page 5 of the book provides the fix:  “Place a space between colons if they are to be used as print separators.”  (Note that the program is to be entered with a space in between the colons, but when LISTed on the screen, the spaces between the colons disappear in TI BASIC.)
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I recently discovered a wonderful TI-99/4A emulator for Microsoft Windows called Classic99.  The emulator is incredibly detailed.  (For example, the screenshot above emulates the screen you would see if you used a television set as the display.)  Although I have used it only for a few hours, I would consider it my favorite software of all time.

This is my first blog entry about the Texas Instruments Home Computer. I plan to write more in the future.