1. ## Powering the TI 89 (and many other calculators) with lithium batteries

The TI 89, like most calculators, uses AAA sized batteries. These vary from 1.5v in the fully charged disposable variants, to 1.2V NiMH rechargable batteries. I wanted to replace the batteries with a rechargable solution that could charge while the device is being used.

Conveniently, 5v fits nicely …

2. ## Getting a dos machine on the network, and getting dosbox to talk it it

I was trying to play multiplayer doom, and not chocolate doom, where one of the machines is a dosbox and the other is a computer I built after a few months of collecting parts from recycling places. The specs:

• Pentium MMX 233 (I found this one taped down to a …

# I found it

http://tict.ticalc.org/docs/J89hw.txt

Yes it! I found it! The document of glory!

/* meanwhile, here's some hackery with i2c on the TI-89 (because I didn't even bother with that untested code from 2004 on the archive) */
#include <tigcclib.h>

/* Notes
The lines …

# Goals

• Replace the batteries with LiPo, tp4056+protection (is the protection needed?) with small slit on the bottom for charging