Ti-Basic Bitcoin Miner

A bitcoin miner for Texas Instruments calculators (Ti-83 Premium CE/TI-84 Plus CE) fully written in Ti-Basic. It should also work on other TI calculators, but I can't check that since I don't have any other. It was written on a Ti-83 Premium CE (french model of the TI-84 Plus CE), OS version 5.2.0. It can't actually generate any bitcoins since it's well too slow to mine on the actual blockchain - it uses old blocks that you can find on https://blockchain.info/.

Hashrate

0.0001 H/S on a Ti-83 Premium CE (2h50 for one block hash)

How to use it

Download Ti-Connect to transfer the files to your calculator.
Enter your block version/prev_block/merkle_root/time/bits/nonce in Str5/Str6/Str7/Str8/Str9/Str0 in BTCINIT.
Start BTCMINE and wait for around 3 hours. Your block hash will be displayed and it will tell you if your nonce is or isn't correct.

How does it works

Since I can't put any comments in Ti-Basic, here is a summary :

• BTCMINE : Takes BTCINIT's block information and generate the block hash.

It uses :

• BTCINIT : Sets some constants, like the block's information and BCHANGE key.
• SHAPREP1 : Puts the block's information in decimal in L1 and preprocess them.
• SHAWLIST : Generates the W(j) list of L1 (W(1)-W(16) are L1(1+16.E)-L1(1+16.E)) in L2.
• SHACOMP : SHA-256 compression function of L2. Output in L6(1)-L6(8) (where the constants were for the second round).
• SHAPREP2 : Moves the hash of the block from L6(1)-L6(8) to L1(1)-L1(8) and preprocess them.
• BTCDISP : Generates the final hash, display it and tell if the nonce was or wasn't correct.

And those use :

• BCHANGE : Changes the base of Str0 (initial base : A | new base : B) - supports bases 2,10,16 (and 36 as input)
• SHACONST : Sets SHA-256 constants in L6.
• CHOOSE : SHA-256 Choose function (inputs : S,T,U | output : V)
• MAJORITY : SHA-256 Majority function (inputs : S,T,U | output : V)
• SIGMA0 : SHA-256 SIGMA_0 function (input : S | output : V)
• SIGMA1 : SHA-256 SIGMA_1 function (input : S | output : V)
• GAMMA0 : SHA-256 GAMMA_0 function (input : S | output : V)
• GAMMA1 : SHA-256 GAMMA_1 function (input : S | output : V)
• ROTATE : Bitwise right rotate through carry function (input : S,T | output : Str0 in binary)

If that doesn't make any sense to you :

• SHA-256 white paper : http://www.iwar.org.uk/comsec/resources/cipher/sha256-384-512.pdf
• A good youtube video on that subject : https://www.youtube.com/watch?v=UZBZPOEVyJA

Future of this project

I don't plan to make a lot of changes to this project, it was done in 2 days to prove how slow those calculators are. It is actually pretty amazing that they can actually do all of this stuff in some ways - and that you can do it with 10 strings. I could optimise it a little more, make a loop that will increase the nonce until the block is solved, but it's well too slow anyway. I know that it would be faster if it was written in C and compiled in ASM, but that wasn't the point : I did everything directly on the calculator, and I can't code in C direclty on my calculator.

How you can help

If you are better than me in english and see any mistakes, feel free to contact me, that's not my native language.
If you have a better calculator (like a TI-Nspire) or an older one (like a Ti-82 Plus) that can run this code, please send me your results so I can write them here.
If you want to improve it, feel free to create a new branch or to ask for collaborator's rights.