The TI-80 calculator came out in 1995 and was, with the TI-84 Pocket.fr, the smallest of the TI calculators ever released. Not much was known of it, with its proprietary processor, its tiny 64*48 screen and its lack of a link port (unless you have the ViewScreen model, who have a port for linking with a computer to take screenshots).

As he told us on TI-Planet, in February/March 2010, critor managed to dump both the 3.0 and 4.0 versions of the ROM with a EEPROM programmer and began analysing them. The mysteries of the TI-80 could be solved, but no. None of the 32KB of code could be recognized, since it's a proprietary processor and not a z80 like the TI-73 to 86, and a lot of the system messages seemed to be lacking from the ROM, as if part of the ROM was stored somewhere else. But where is the missing part of ROM? The TI-80 actually stocked the ROM in two different chips: a LH5359 ROM of 64KB capacity, and the proprietary Toshiba T6M53A processor. Unfortunately, no documentation on this processor had been found and no other known devices uses it.

Fortunately, Randy Compton studied the ROMs Critor dumped and found out a TI-BASIC glitch allowing him to dump the entire ROM on-screen. From there, he found 16KB was missing for a total of 48KB and began transcribing the ROM character by character. 97% of the ROM was dumped this way, the rest was non-displayable characters and pairs of codes showing the same character.

Randy didn't stopped there. He then managed to get his hands on a rare TI-80 ViewScreen with ROM 4.0, who have a linkport, and wrote the first ever assembly program, allowing him to dump the entire ROM through the link port, only used until then to take screenshots. The first complete ROM dumping of a TI-80 v4.0 was made.

To conclude this act of wizardry, Randy then wrote the first ever TI-80 emulator, made available today on TICalc and TI-Planet (in french). He also made a documentation available here. The TI-80, the last pre-Nspire calculator to lack an emulator, is now emulated. Randy won't stop there either. He also announced a kernel allowing ASM programs to be ran, a dumping program (the ROM isn't included with the emulator) and programs to transfer data via the link port.

After 15 years, the last locked TI calculator has now been unlocked, thanks to Randy Compton.

I saw this on ticalc.org this morning at school, and would have posted about it if Omnimaga weren't blocked there.
However, it's not very useful for most of us, who don't have a ROM
A great achievement nonetheless!

Omni's blocked at your school?

Whoakay, awesome

Even the TI-80 is now emulated.

Wow!  That's awesome! 
How did he figure out the ASM opcodes?

Wow! That's quite a feat.
I'm very interested to learn how he reverse engineered an instruction set for an undocumented, proprietary processor.

Cheers! To the emulation of Texas Instrument products!

Wow, this is awesome news to be sure. Wasn't Randy also one of the people involved in hacking the TI-81? I have a TI-80, but not one with a link port. No way to get a ROM dump from it.

Also, it's official: Randy Compton is a freakin BEAST.

We have emus for all the calcs now!

Edit: Minus CX and other color-nspires, I guess.