Four Column ASCII (via) is a reformatted version of this Hacker News comment that presents the ASCII chart in four columns of 32 characters instead of the usual presentation of eight columns of 16 (as seen eg here). A four column representation makes a number of patterns in ASCII (both bit-wise and otherwise) much clearer, for example why Ctrl-Space, Ctrl-@, and Ctrl-` all generally generate a null byte.

(I suspect that ASCII is traditionally presented in an 8 column by 16 row table because that fits into an 80x24 terminal or terminal window.)