I remember these registers fondly. I haven't got any notes on them any more so you will need a manual. I send my customers to C-tech as thats the only place I know of where you can download the programming manual. Hope this helps:
https://the-checkout-tech.com/manuals/cashregisters/Towa_ET-7626_and_MR1_programming_manual.html
Don't worry about the different model number. It was re-branded for the UK by Geller
Registerman, February 2015