And Other Math Stuff

Very Sad Fact: My TI-85 was stolen last week. )-:

Calculator Hacks

The 4-Buck Serial Link (TI-82/85/92)

The 4-Buck Serial Link - Frequently Asked Questions

Link Cable Connector Schematic (TI-82/85/92)

Finding your ROM Version

CalcSound (TI-85)

TurboTI - Accellerate your calculator (TI-85)

TI-85 Emulator for PCs (TI-85)

Andreas Westfeld's $5.00 Parallel-Port Link

Info on the "$5.00 Parallel-Port Link"

ZShell (TI-85)

The Unofficial TI Calculator Page

This page was initially contstructed for the sole purpose of hosting the schematic that I made for the 4-buck serial link (since there had been nothing but ASCII schematics previous). Then that expanded into somewhat of an answers to frequently asked questions page (like the "330R" question.) Since that got so many hits, I kept adding stuff. And now we have what you see here... If you have any suggestions, please mail me.

The 4-Buck Serial Link

Most of us who have TI calculators have long wanted a gizmo to hook the calculator up to the computer to transfer files. However, we didn't feel like spending the $50 ($75 with Educational "discount") for the TI-Graphlink cable. Thankfully, Timo Stenberg invented his "Four Buck Serial Link." It requires it's own special software, but hey, it costs less than $4.00. It's quite simple to build and the parts are easy to obtain. Click on the schematic at the left for a bigger version that's easier to read. Then, get the software and instructions here.

Quant	Description	RS Cat No.
Parts List
2	3.3k ohm resistors	271-1328
1	330 ohm resistor	271-1113
2	4.7v (approx) Zener Diodes	276-565
1	LED with 2v drop	276-1622
1	Serial Connector
1	TI Calc Link connector

Frequently Asked Questions about the $4.00 Serial Link

Q: Does the link work?
A: Yes, and it works quite well.

Q: How much does the link cost?
A: As the name implies, about us$4.00, depending on the size of your spare parts box.

Q: Can I buy a link from you?
A: Not yet. But soon. Email me if you're interested.

Q: What calculators does it work with?
A: I know it works with the TI-82 and TI-85, but I'm not sure about the TI-92. The TI-81 has no link port.

Q: The schematic says to use a 4.7v Zener Diode, but the RS part number you give is for a 5.1v Zener diode.
A: Doesn't matter - either will work. RS doesn't carry the 4.7v variety.

Link Connector Schematic

Hooking up the connector
Jack 2.5mm stereo \| \| - GND (Ground) \|_\| \|_\| - W (White wire) \|_\| - R (Red wire)	Sleeve ---- Ground / Braid White ---- Ring Red ---- Tip

Parallel Link Information

Andreas Westfeld invented this link hardware for the TI-85 and TI-92 which connects through the parallel port of your computer. For construction information, click (English) or (German).

Many people complain that this link doesn't work for them. Here are common places for trouble:

Requirements for this link

gork@arn.net

You must have a bidirectional parallel port.
Your parallel port must be at a standard address.
Don't try to use it through a chained parallel device. (eg. Backpack CD-ROM, tape drive, Zip drive, etc.)
You must use the LINK85XP.EXE program to transfer files. (LINK92XP.EXE for the '92) The link doesn't work with 82's.
You must have a PC. (ie, not a Macintosh)

As for diodes, try a small silicon switching diode like the 1n4148. Any of the generic cylindrical, radial packaged, small silicon switching diodes that are black with one silver or white band from radio shack should work fine. Apparently 5.1v Zener Diodes work fine, also.

CalcSound

Ever want sound from your calculator? Eric Linenberg [ELinenberg@gnn.com] describes how:

Here are the directions to make your very own MONO calculator speaker which DOES NOT lock up your calc outside of ZShell. I am in the process of a 2- speaker STEREO version, but I will post that later.

Parts

Miniature PCB-Mount Piezo Buzzer (RS cat# 273-074)
TI calc-to-calc link
Solder, or at least electrical tape
Electrical tape

Directions

Chop your link near one head through the thick part of the rubber. If you want you can chop it closer to the plug but you'll have to break through the (ceramic?). Take the non-covered wire and solder it to the end of the buzzer (this is on the front of the buzzer.)
To the other speaker input, attach the red and white wires.
Then with electrical tape attach the buzzer cleanly to the butt of the head of the link.
That's it. I am going to the electronics store today to see if they have a low voltge speaker, because the sound from the buzzer is slightly inferior to that of headphones but with others around you can hear it like in school. So it's very cool.

TI-85 Emulator

There's a very cool TI-85 emulator and ROM 10.0 image available at ftp://users.aol.com/davidells/TI-Calc.

TurboTI-85

To make your TI-85 calculator at least twice as fast, open it up. Then place a 1.0pf capacitor in series with capacitor C9. If you wish to add a "turbo switch," add a switch in parallel to the 1.0pf capacitor that you have added. To turn turbo off, flip the switch, which will in effect eliminate the 1.0pf capacitor by shorting it out. Note that C9 is 33pf.

Be careful, surface mount components are a pain to work with.

Here is the idea: (from  Isaac Salpeter [ias3110@pobox.com])

                      __1pf_
lower                /      \
pad of C9---[33pf]--|        |----upper pad of C9
                     \      /
                      switch

There is a good text file on Accelerating The TI-85 by Keith L. Miller at here

There's more miscellaneous info here.

SSHD

There is an interesting project underway to create an external "Solid State Hard Disk" (SSHD) for the TI-85 using an external I2C memory chip.

I'm currently working on making a nice graphical schematic.

Info is available here.

Finding your ROM Version

To find out what ROM version your calculator has, hit [2nd] [Mode] [Alpha] [S]. The calculator will say "Enter Self Test," under which is your ROM version. Hit [exit] to leave this menu. If you hit [Enter], your memory will be erased.