> uppercase letters start at 0x41, and lowercase letters start at 0x61 And the reason for the 0x20 difference is that the Shift key on old teletypes turned the

> uppercase letters start at 0x41, and lowercase letters start at 0x61 And the reason for the 0x20 difference is that the Shift key on old teletypes turned the 0x20 bit on and off. In the same way the Control key turned the 0x40 bit off. So Ctrl-A = 0x01 = 'A'/0x41 - 0x40.