The 1963 standard⁰ answers your questions. (Probably the final 1967 version does too, but it's not online anywhere.) In this instance the more common 8-column

The 1963 standard⁰ answers your questions. (Probably the final 1967 version does too, but it's not online anywhere.) In this instance the more common 8-column presentation actually better reflects the design. It's important that the low 4 bits of '0' are 0. The 0x2X column and 0x3X column are related by shift (on some devices²). ⁰ http://worldpowersystems.com/archives/codes/X3.4-1963/index.html http://worldpowersystems.com/archives/codes/X3.4-1963/index.... ¹ https://en.wikipedia.org/wiki/Binary-coded_decimal https://en.wikipedia.org/wiki/Binary-coded_decimal ² https://en.wikipedia.org/wiki/Bit-paired_keyboard https://en.wikipedia.org/wiki/Bit-paired_keyboard