Hacker News Reader

So you'd get "PNG" printed out when you accidentally "type"ed that file in MS-DOS. The 1A was the EOF character for text data back then.

Ah, that makes a lot of sense!

So what's 0x89 at the start? It's outside the ASCII range.

So when a 7-bit transfer masks out all highest bits, it becomes a invalid signature instead of the pixel data getting silently corrupted.