Every time I sit down at a vintage Macintosh computer, there is an adjustment period when using the keyboard. I feel for the keyboard bumps using my index fingers to begin typing. This is because they are on the F and J keys on modern Macs and Windows computers. However, the position key bumps are on the D and K keys on Macs from the 80s and early 90s.
I finally started digging for some information on the changeover and found this Apple Support document about the “bumps” on the home keys
At some time in Apple’s history it was decided to put the “bumps” on the D and K keys while some other computer companies use the F and J keys. With the release of the PowerBook G3 Series, Apple moved the bumps to the F and J keys. Apple engineering has indicated there is no standard, such as ISO or ANSI that specifies which keys should have these “bumps,” or that they should have the “bumps” at all.
I learned typing in a school computer lab filled with “pizza box” Macs, and I remember the teacher saying something like, “use your middle fingers to find the home row keys because they are our longest fingers.” But it seems like it was just a fluke that those keyboards were setup like that and not for some “logical” reason.
After over 25 years of both Windows and Mac keyboards using F and J for position keys, and vintage Mac keyboards just feel weird.