\catcode`\{=1 % left brace is begin-group character
\catcode`\}=2 % right brace is end-group character
\catcode`\$=3 % dollar sign is math shift
\catcode`\&=4 % ampersand is alignment tab
\catcode`\#=6 % hash mark is macro parameter character
\catcode`\↑=7 % circumflex is for superscripts
\catcode`\_=8 % underline is for subscripts
\chardef\active=13 \catcode`\~=\active % tilde is active

\let\bgroup={ \let\egroup=}