In some systems, backspace was not buffered. It shifted the last offset position of the memory position to be stored for the next character. Backspace may just

In some systems, backspace was not buffered. It shifted the last offset position of the memory position to be stored for the next character. Backspace may just be pc--, and every other character is just a poke. This is pre-ASCII. There was no standardisation of how you might expect input to work. For example, there is no backspace character in unshifted PETSCII.