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

My first association for this symbol isn’t a house, but an indent marker, like here (“Right Indent Box” in particular): https://www.atlantiswordprocessor.com/en/help/images/ruler.p...

Or here as a tab stop in GeoWrite (in the top left, below the “file” menu): https://static.wikia.nocookie.net/commodore64/images/6/68/Ge...

Some mechanical typewriters had physical markers/stops that looked similar. The best I could find in a hurry: https://www.mrmrsvintagetypewriters.com/cdn/shop/files/DSC_7...

Wow this is a beautiful article. I love Code page 437 - my first experiences with computers used it. I made two little things that are a homage to the pixelated and "cyberpunk" "screaming electron" "information superhighway" glory that is IBM Code Page 437:

1. Endless scrolling random Code Page 437 text: https://o0101.github.io/random/ (but it seems to be broken indicated by an overabundance of the non-existent "block question mark". Code here in case anyone wants to submit a fix :) : https://github.com/o0101/random)

2. Base-437 - a way to encode any binary file into faithful-to-code-page-437-glyphs that you can nevertheless throw into HTML no problemo: https://browserbox.github.io/Base437/ This means, for instance, you can have a "data:image/png;base437,ëPNG♪◙→◙ ♪IHDR ◘♠ \r¿f ♦gAMA Åⁿa♣ cHRM z& Çä · ÇΦ u..." URI for an image. I just think it looks cool being able to see the content rather than base64 which hides it. Code: https://github.com/BrowserBox/Base437

Linked in this article is VileR's excellent website <https://int10h.org/>. In fact, it is linked 8 times in this article. If this kind of thing interests you, I highly recommend following those links. VileR's site is probably the best resource we have today that preserves the various PC OEM fonts from a bygone technological era -- an era that lives on in the memories of those of us who first encountered these machines early in life.

I'm genuinely in awe of the time and effort VileR has poured into recovering each font, and their countless variants, from a wide range of ROMs. The site not only archives them all with incredible attention to detail, but also offers live previews, aspect ratio correction, and other thoughtful features that make exploring it a joy. I've spent countless hours there comparing different OEM fonts, and hunting down the best ones to use in my own work!

Wow, it really goes in depth on the topic, in the beginning I was like "wtf am I even reading this" and after a while I was hooked by the writing style, the depth of the research and also the design of the website. Really, really cool.

I seem to recall whether 0xE1 in codepage 437 is supposed to be a Greek lowercase beta (β) or a German sharp s (ẞ) is intentionally a bit fuzzy, so its perhaps they intended it to be both a delta and a dingbat.

I'm not really sure if a house fits it that much, wouldn't a generic "house" symbol have a chimney (although obviously, it's hard to fit one in with such a low resolution).

There’s a certain amount of “it just is” when it comes to non-textual characters. I remember being interviewed by a reporter from The Wall Street Journal about the claim that Wingdings had an antisemitic message secretly encoded in it because NYC output as the sequence skull and crossbones-star of David-thumbs up, but the choice of where those characters were encoded is purely a consequence of grouping similarly themed characters together (so, e.g., the star of David comes in the midst of a sequence of religious symbols).

Really good article! Personally it has me convinced that the 0x7F character was originally meant to be a delta, but whoever drew it did a poor enough job that it made other teams at IBM think it was supposed to be a house. As the article says, when you look in the PC BIOS source listing, there's a comment saying "DELTA" next to where the bitmap for the 0x7F character is defined. https://github.com/philspil66/IBM-PC-BIOS/blob/main/PCBIOS.A...

I think those symbols were so underutilized, IBM didn't care about cementing their names. It's an ambiguous triangle. Use it as delta. Use it as a house. It doesn't matter because the programmers are the ones that give it true purpose.

This was a fantastic article. The ASCII art alone is worth a click.

My guess: it's the "mode change" code found in various IBM punchcard encodings, punch 11-8-7, canonically represented by an upper-case delta.

It would make sense to render this somewhat differently from the regular Greek character. This may also explain why it's rendered differently in various manuals: once, as commonly represented in EBCDIC charts, as a delta, once, as it's actually represented in the on-screen character set.

One more theory - it could be a tabulator or cursor symbol (for word processing applications).

What I remember from my experiences with terminals and printers (the only display devices available at the time) from 1978-1980 was that the 0x7F <DEL> character rendered as a checkered box. This correlates with (0xFF) Figure 5 in the article. This was common among all printers I worked with, Teletype, Epson, Okidata, TI, Printronix, and even IBM. Also all the Lear Siegler, Televideo, DEC, Hazeltine, terminals I used did something similar. Even the character ROMs in my Ferguson Big Board II, and Kaypro II used the same checkered box pattern.

> There is just one thing I cant't quite comprehend. Let's assume for a second that DEL was supposed to be delta. Did IBM seriously not try different ways of drawing a delta, before settling on the house glyph? With a little bit of effort, it is completely possible to draw a convincing delta, even in 8×8 pixel space.

But exactly the same argument applies to the Greek fonts where something that looks even more like a house is unmistakably intended to be delta, since it sits between gamma and epsilon. They could have made that looks like a triangle, but didn't.