What's the correct Unicode code point for the Apple IIe's "delete" symbol?

Question

I was writing an essay today about using the Apple IIe I grew up on, and I wanted to add some examples that included the "delete" symbol that was used for the cursor:

But try as I might, I couldn't find this anywhere in Unicode. The Unicode Block Elements include ░ and ▒, and Unicode Geometric Shapes includes things like ◼ and ▣ and ▩, but none of those are that very distinctive 5x5 checkerboard.

The recently-added Symbols for Legacy Computing block includes MouseText's shading characters, but still not the unique Apple IIe "delete" shape. Since Unicode didn't add it to "Symbols for Legacy Computing," that would presume it exists somewhere else in Unicode already, but I haven't been able to find it, and this approximation with a box simply doesn't look right:

]10 PRINT "HELLO, WORLD"□

So is there an actual Unicode code point for this character? Does it have a better name than just "the delete symbol"? Did it get left out of Unicode?

Answer 1

TL;DR:

There is no 'REVERSE FIVE-BY-FIVE CENTERED CHECKER BOARD' (*1) in all of Unicode's blocks. Closest by looks and positioning might be the

• "REVERSE FOUR-BY-FOUR CHECKER BOARD" U+1FBA6

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Alternatives

The

• "SQUARE WITH DIAGONAL CROSSHATCH FILL" U+25A9

might be a good close choice if it's about recreating the appeal independent of output media while

• "BLACK SQUARE FOR STOP" U+23F9

from the Media Control section will most often result in the right placement.

Those are, unlike the 'Symbols for Legacy Computing', of older addition, thus more likely to be present in output charsets for your document. Ignoring the rendering issue, I would think the

• "REVERSE FOUR-BY-FOUR CHECKER BOARD" U+1FBA6

would do the best job creating the impression of the checker board nature of the IIe character. As shown with modern '8 bit games', it's only relevant what impression is created, not that it's really in all details true to source material (*2).

No Chance for the Real One?

Well there is. Adding a

• "SYMBOL FOR DELETE SQUARE CHECKER BOARD FORM" at U+2427

was proposed January 2022 and might as well be on the road to addition. It may take some time until fonts will adopt it, so until then the reverse 4x4 should do the job.

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Background

Apples Choice

The 5x5 middle aligned checkered symbol is what Apple placed as glyph for the DELelte character ($7F). As a code to remove any other code it does by nature not have any visualisation (*3). With this it has been a common code place for machine specific additions (*4).

MouseText

The checker board is not part of Mousetext. Its two 'half' filled blocks at code position $56/$57 are different and represented by "MEDIUM SHADE" (U+2592) and "INVERSE MEDIUM SHADE" (U+1FBA0).

The Questions

[...] would presume it exists somewhere else in Unicode already

Nop, it doesn't.

and this approximation with a box simply doesn't look right:

]10 PRINT "HELLO, WORLD"□

Why? I do in fact think of that as a very good representation. Not at least as it should work with most output media due being an older addition.

So is there an actual Unicode code point for this character?

No

Does it have a better name than just "the delete symbol"?

No, not even that, as that naming is only true for the Apple IIe.

Did it get left out of Unicode?

Yes.

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*1 - Unicode naming of "REVERSE FIVE-BY-FIVE CENTERED CHECKER BOARD" a in

• INVERSE since Unicode description is made assuming a black on white rendering and a checker board starts out with white in the top left corner, but ours need to be black
• FIVE-BY-FIVE as the obvious structure
• CENTERED as we want to have it hover in the middle of the character cell
• CHECKER BOARD to denote the alternating fore-/background scheme

*3 - Many of those modern '8-bit' style games do not really use scaled up 8 bit graphics but high resolution, often even 3D models made to give that look while still using finer details. Did already turn me off more than one otherwise nice game.

*3 - Beside using it's control picture of U+2421 ␡ [DEL].

*4 - Commodore used for example a "SQUARE WITH UPPER LEFT TO LOWER RIGHT FILL" (U+1FBA7) or "BLACK UPPER RIGHT TRIANGLE" (U+25E5) depending on charset.

Answer 2

Only because @trikly asked (in this comment), from the relevant Unicode documentation(PDF), the three new "Specific symbols for delete" that have been accepted for future inclusion in the standard: (Seems Apple wasn't the only system to use such a symbol to represent Delete.)

Specific symbols for delete

• 2427 SYMBOL FOR DELETE SQUARE CHECKER BOARD FORM
  • symbol for delete in the Apple II character set
  • fills the bounding box of 002B +
• 2428 SYMBOL FOR DELETE RECTANGULAR CHECKER BOARD FORM
  • symbol for delete in the TRS-80 character set
  • fills the bounding box of 0048 H
• 2429 SYMBOL FOR DELETE MEDIUM SHADE FORM
  • symbol for delete in the Amstrad CPC character set, which also encodes 2592 ▒ separately
  • fills the character cell → 2592 ▒ medium shade

Answer 3

In order to determine what Unicode symbol should be associated with that character, one would have to ascertain what the dot pattern was supposed to represent. The particular pattern of dots used for the character was chosen to fit in a 5x8 matrix, and some design aspects might have been different if a different size of matrix had been used. In a 7x9 matrix, for example, there might have been four illuminated pixels on each side of the shape rather than three, or the shape used for the 5x7 matrix might have had a frame added around it (trying to have a frame around a checkerboard pattern in a 5x5 area would make the middle look like an "X" or "O" rather than a checkerboard). If one assumes the goal was to have a shaded square which does not fill the character box, I think Unicode points 25A7 through 25A9 ("Square with [different kinds of diagonal] Fill") would all be perfectly reasonable candidates, with 25A9 probably being the best. Point 25A9 looks reasonable in both normal and fixed-spacing fonts: ABC▩EFG and ABC▩EFT; it's centered within the X height, but shorter, and its interior is filled but not solid.

Another possibility would be 203B "Reference Mark" which looks like "ABC※EFG" or ABC※EFG. It wouldn't match the dot pattern when magnified, but one would hardly argue that character 0x2F shouldn't be recognized as a slash, but rather as a diagonal sequence of five dots. Someone given the task of representing ※ in a 5x7 matrix would be likely to produce the exact same pattern of pixels as Apple used for their 0x7F character.