alt Hacker NewsThe idea was that the free bit would be repurposed, likely for parity.
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This is not true. ASCII (technically US-ASCII) was a fixed-width encoding of 7 bits. There was no 8th bit reserved. You can read the original standard yourself here: https://ia600401.us.archive.org/23/items/enf-ascii-1968-1970...
Crucially, "the 7-bit coded character set" is described on page 6 using only seven total bits (1-indexed, so don't get confused when you see b7 in the chart!).
There is an encoding mechanism to use 8 bits, but it's for storage on a type of magnetic tape, and even that still is silent on the 8th bit being repurposed. It's likely, given the lack of discussion about it, that it was for ergonomic or technical purposes related to the medium (8 is a power of 2) rather than for future extensibility.
I would love to think this is true, and it makes sense, but do you have any actual evidence for this you could share with HN?
When ASCII was invented, 36-bit computers were popular, which would fit five ASCII characters with just one unused bit per 36-bit word. Before, 6-bit character codes were used, where a 36-bit word could fit six of them.