Editing Macintosh XL (section)

=== Display System ===

==== Rectangular Pixel Issue ====
Unlike all true Macintosh computers, the stock Macintosh XL displayed rectangular pixels with a 3:4 width-to-height ratio. This caused significant distortion when running Macintosh software:<ref>{{cite web |url=https://www.folklore.org/StoryView.py?project=Macintosh&story=Square_Dots.txt |title=Square Dots |author=Andy Hertzfeld |publisher=Folklore.org |access-date=2025-01-25}}</ref>
* Circles appeared as vertical ovals
* Squares looked like tall rectangles
* All graphics appeared stretched vertically

==== Macintosh XL Screen Kit ====
Apple offered the Macintosh XL Screen Kit to address the pixel aspect ratio problem. The kit included:<ref>{{cite web |url=https://lisafaq.sunder.net/single.html |title=The Apple Lisa FAQ |publisher=Lisa FAQ |access-date=2025-01-25}}</ref>
* New 3A boot ROMs
* Modified video state ROM
* Replacement yoke coil for the CRT
* Installation instructions

The Screen Kit changed the display resolution from 720×364 to 608×432 pixels, providing:
* True square pixels matching the Macintosh
* 50% more screen area than the Mac's 512×342 display
* WYSIWYG compatibility with Macintosh software
* Professional appearance for graphics applications