Explaining Small House in PC's OEM fonts

[EdS]

There’s a very readable article here digging into the 0x7F character in the IBM PC’s OEM font (later code page 437)

Why is there a "small house" in IBM's Code page 437?

Why did IBM decide to include a symbol representing a house in their character set? It’s a strange glyph; adding a smiley is readily arguable, and playing card suits have existed in prior character sets, but a house—as far as I can tell—it didn’t exist as a glyph anywhere before IBM’s Code Page 437. It seems to come out of thin air. To my knowledge, there are no (surviving) documents on the design process of the character set. The little bit we know comes from a few interviews, like the one with David J. Bradley, and from meticulous research done by people like VileR. So, the only thing I can do is speculate. Here are my thoughts…

Much PC-character-set art within… I wish I could call it ASCII art - much from the site INT 10h which celebrates exactly that.

Not far away we find another article of interest:

The origins of DEL (0x7F) and its Legacy in Amiga ASCII art

via Delta House. : languagehat.com

via a-b-c-d-x-y-z...HOUSE? | MetaFilter

also discussed at HN

[NoLand]

The Amiga ASCII art article is great!

Regarding our special character, I do think that this passage on ITA2 encoding gives it away:

The pattern of five punched holes (❶❶❶❶❶) activates the letter mode and ❶❶⓪❶❶ activates the figure mode. Any binary sequence following a mode shift prints the character in that mode.

Notably, on (IBM) punchcards, punch 11-8-7 is “mode shift”, serving the same purpose, and is represented by an upper-case Delta. I do think, this is what this is.
It does make sense to render this somewhat differently in a character set that does comprise Greek letters, to differentiate this from the actual Delta. It’s drawn the same way, but at a narrower height. And it’s vertically centered – so this is not a “normal” character (rather, indicating a function symbol).

(0x7F versus Delta.)