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Re: Square pixels?

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On Monday, June 7, 2021 at 8:20:18 AM UTC-7, Thomas Harte wrote:
> I am the author of an Apple II emulator; I recently received a bug report that its pixels aspect ratio is off — e.g. in text mode, pixels are not square. 

AppleWin developer here.

I've never known any Apple 2's using a TVs or Apple monitors to have 1:1 aspect ratio (AR).  The consensus is that a 4:3 AR is the de facto standard.

Using pixels, 280/192 = 1.45... which "roughly" matches 4:3 = 1.333.

If you draw a circle you will need to use scaling to have it display without it looking like an ellipse.

We had a thread about this back in 2017 called: Emulator aspect ratios?
* https://groups.google.com/g/comp.emulators.apple2/c/YUsAV1BX1Ks

At the time I posted this information:  (There was a bug in the original code, here is the fixed version)

# Code

HGR
CALL-151
c051 n c054
2000:7f
2027:7f
3fd0:7f
3ff7:7f
c050 n c052

# Measurements

Apple Color Monitor
===================
Width: 9.5"
Height: 7"
Diagonal: 12"

Franklin Color Monitor
======================
Width: 9" or 22.5 cm
Height: 6.5" or 16.5 cm
Diagonal: 11"
Aspect Ratio (Width/height):

# Calculations

Apple:
DPI Width: 560 dots/9.5 inches = 58.94 dpi
DPI Height: 192 dots/7 inches = 27.42 dpi
Aspect Ratio (Width/Height): 9.5 / 7 = 1.35

Franklin:
DPI Width: 560 dots/9 inches = 62 dpi
DPI Height: 192 dots/6.5 inches = 29.58 dpi
Aspect Ratio (Width/Height): 9 / 6.5 = 1.38

Ergo, the aspect ratio is very close to 4/3 = 1.33.

Hope this helps.

m.

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Square pixels? Thomas Harte <thomas.harte@gmail.com> - 2021-06-07 08:20 -0700
  Re: Square pixels? kegs@provalid.com (Kent Dickey) - 2021-06-07 16:44 -0500
  Re: Square pixels? cybernesto <cybernesto@macgui.com> - 2021-06-26 15:49 +0000
    Re: Square pixels? Michael J. Mahon <mjmahon@aol.com> - 2021-07-05 11:08 -0500
  Re: Square pixels? "Michael 'AppleWin Debugger Dev'" <michael.pohoreski@gmail.com> - 2021-07-07 09:10 -0700

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