There are a couple signs of strain beyond the MacBook Neo and the desktops. Apple's Mac mini, which is a nice desktop if you can buy it. Credit: Andrew Cunningham Apple's Mac mini, which is a nice desktop if you can buy it. Credit: Andrew Cunningham The Apple Macintosh is more than 40 years old, but it’s still going strong, and its recent success was significant enough that Apple CEO Tim Cook called it out during the company’s earnings call last week . In particular, Cook credited the new low-cost MacBook Neo, which Apple says is attracting a fair number of new Mac buyers rather than simply prompting upgrades from previous customers. But Cook also noted that the Mac’s success was being held back somewhat by “supply constraints… on several Mac models,” which was exacerbated by “less flexibility in the supply chain” than Apple was used to; the company also expects to pay “significantly higher” prices for RAM than it has been so far.…