The Apple II graphics resolution modes could be mixed with text. So that is to say, in either the lo-res or hi-res modes, a hardware register setting would conceal a bottom portion of the graphics frame buffer, revealing four lines of the text mode.
I think all the circuitry for shifting out the pixels must have been very minimal and shared between the text and hi-res mode.
So, .. if you recall, the character cells in the 40 column text mode are all also 7 pixels wide. The character cells were 7x8. In that space, a certain font fit exactly, with a two pixel space between characters. Here is A:
OOO |
O O |
O O |
OOOOO |
O O |
O O |
O O |
|
-------+
In high res graphics mode, you could create a bold font, by using the extra column:
Anyway, the high res graphics mode pixels coincided exactly with the text mode pixels. You could imitate the text mode using high res graphics, and it would look indistinguishable. (Except for not being able to make the characters blink simultaneously, though even that could be sort of faked with page flipping.)
I think that in a 8x8 character cell that would result from a 160x192 mode (40x24 text), it might have been more awkward to design the font. You want an odd number of pixels, for symmetry, so probably characters will be 7 wide. 5 would leave 3 pixels of space, which might be too much. For designing 7 pixel font glyphs, maybe 7 scan lines is not enough height.
It's possible that part of the decision was around the design of the text mode and its font, and the high res graphics was tied to that, pixel for pixel.
I think all the circuitry for shifting out the pixels must have been very minimal and shared between the text and hi-res mode.
So, .. if you recall, the character cells in the 40 column text mode are all also 7 pixels wide. The character cells were 7x8. In that space, a certain font fit exactly, with a two pixel space between characters. Here is A:
In high res graphics mode, you could create a bold font, by using the extra column: That was seen in a lot of games.Anyway, the high res graphics mode pixels coincided exactly with the text mode pixels. You could imitate the text mode using high res graphics, and it would look indistinguishable. (Except for not being able to make the characters blink simultaneously, though even that could be sort of faked with page flipping.)
I think that in a 8x8 character cell that would result from a 160x192 mode (40x24 text), it might have been more awkward to design the font. You want an odd number of pixels, for symmetry, so probably characters will be 7 wide. 5 would leave 3 pixels of space, which might be too much. For designing 7 pixel font glyphs, maybe 7 scan lines is not enough height.
It's possible that part of the decision was around the design of the text mode and its font, and the high res graphics was tied to that, pixel for pixel.