Apple Computer 1

The auction house Bonhams had a History of Science auction last October 22, 2014 in New York. Among the highlights was an Apple-1 computer with exceptional provenance and in beautiful, working condition. (I got the pictures here from the Bonhams website). It was estimated to sell for US$ 300,000 to US$ 500,000. Continue reading “Apple Computer 1”

Panasonic JE-885U

885l 885nm 885r I asked my mother for the Panasonic 885 electronic calculator she used when I was a child. It uses four AA size batteries or an AC adaptor. Some of the keys no longer work, and I haven’t tried to check if the AC adaptor still works. The power switch reveals a red metal square when the unit is turned on. The case is made of imitation leather stitched at the edges and at the corners. I love its design—the colors, shapes, and fonts. I just found out that when holding the unit with the left hand (and pressing the keys using the right hand), the user could put his or her left thumb on the space with the word “Panasonic.”

885c 885a Continue reading “Panasonic JE-885U”

Shirriff’s Sinclair Scientific simulator

Ken Shirriff has reverse engineered the Sinclair Scientific, an incredible 12-function scientific calculator made by Sinclair Radionics in 1974. (I got the picture on the left from here.) He reports the details here. According to his August 30, 2013 blog post:

I’ve reverse-engineered the Sinclair Scientific calculator. The remarkable thing about this calculator is they took a simple 4-function calculator chip and reprogrammed its 320-instruction ROM to be a full scientific calculator. By looking at the chip, I’ve extracted the original code, reverse-engineered how it works, and written a JavaScript simulator that runs the original code and shows what the calculator is doing internally.

Adventure in Oz

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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.

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Continue reading “Adventure in Oz”

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.)
Continue reading “CHAOS”



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.