Tic-Tac-Toe for HP-85 and HP-41C

The famous Tic-Tac-Toe game for HP-85 computers as well as HP-41 calculators. There is also a variant of the programs where an HP-85 plays against an HP-41 connected via HP-IL, a reference to the movie WarGames.

Requirements

To play Tic-Tac-Toe against an HP-85 computer or an HP-41 calculator, you can use one of the emulators listed below. Of course, the preferred and funnier way is to play it on real vintage hardware!

If you want to let an HP-85 play against an HP-41, you need the real hardware as well as an 82938A HP-IL interface for the HP-85 and a 82160A HP-IL interface for the HP-41. Furthermore, the 82938A interface has to be configured as Non-System Controller (because the HP-41 always assumes the role of system controller). Unfortunately, the preset is System Controller and you have to open the interface to change this setting. I've modifed my 82938A interface and installed a toggle switch so I can change the mode without opening it.

The Programs

• HP-41 programs:
  • ./src/41ttt-ppc.txt: This HP-41 program was written by Christopher Rath (thank you!) and requires the PPC module. I used it as the base for the other HP-41 programs.
  • ./src/41ttt.txt: Mostly identical to 41ttt-ppc.txt except that it does not need the PPC module.
  • ./src/41tttil.txt: This HP-41 program plays Tic-Tac-Toe against an opponent connected to the calculator via HP-IL.
• HP85 programs:
  • ./src/85ttt.txt: This HP-85 program plays Tic-Tac-Toe against a human opponent. The board is displayed as graphics.
  • ./src/85tttil.txt: This HP-85 program plays Tic-Tac-Toe against an opponent connected to the computer via HP-IL.

Loading Programs

• The most boring and time consuming way is to type the programs into your computer or calculator.
• If you own an optical wand 82153A for your HP-41 calculator you'll find barcodes of the programs in directory ./barcode.
• If you use the V41 emulator you can load the programs using the *.raw files in directory ./bin. Of course this works for many other HP-41 emulators.
• If you use Everett Kaser's HP-85 emulator there is a disk image TTT85 in directory ./disks containing all the HP-85 programs.
• If you own a PIL-Box you'll find a disk image TTT41 in directory ./disks containing all the HP-41 programs.

Usage

All the programs use the board layout shown below. To make a draw just enter the number of the corresponding square.

+---+---+---+
| 7 | 8 | 9 |
+---+---+---+
| 4 | 5 | 6 |
+---+---+---+
| 1 | 2 | 3 |
+---+---+---+

41ttt-ppc and 41ttt:

• XEQ "TTT"
• Enter seed, then press R/S
• The calculator randomly selects who starts the game
• If it's your turn enter your draw and press R/S
• After some thinking the calculator will display his draw

85ttt:

• should be self-explaining, just RUN it.

41tttil and 85tttil:

• Make sure that the HP-85 HP-IL interface is configured as Non-System Controller.
• Connect the HP-41 and HP-85 via HP-IL interface.
• RUN the HP-85 program.
• When you're prompted to start the opponent, run the HP-41 program entering XEQ "TTTIL".
• Watch and enjoy!

Emulators

HP-85: A fantastic emulator of the great HP-85 computer, written by Everett Kaser. Still actively maintained and extended.

HP-41C: There are many excellent HP-41 emulators. Personally I most often use V41 written by Warren Furlow, the maintainer of the hp41.org site.

References

• Christopher Rath: Tic-Tac-Toe Algorithm & HP-41C Implementation.
• Jean-François Garnier: HP-IL Resource Page.
• pyILPER: a great emulation of virtual HP-IL devices.