Three and a half years ago, Apple released the iPhone 4 which introduced the world to the then-new Retina display.

In Apple's parlance, Retina is basically a cleverly-coined marketing moniker which stands for a screen with pixels so densely packed that the average eyesight (20/20 vision) is unable to discern the individual ones at normal distance.

Apple has since Retina-fied its iOS device lineup, including some Mac notebooks. With the exception of the MacBook Air which stayed at 1,366-by-768 and 1,440-by-900 pixels for 11 and 13-inch models, respectively, we've been kinda keeping our fingers crossed for a Retina iMac this Fall.

Apple instead gave us a radically different Mac Pro as its first desktop so powerful it's capable of driving three 4K displays simultaneously.

One would also expect Apple would by now have released a Retina Thunderbolt Display because the product's been unchanged for almost two years. Instead, the firm opted for the waiting tactics until Retina-grade desktop screens become available at consumer prices.

That day is now looming as Dell on Monday released two 4K desktop monitors starting at just 50 percent more than the $899 Apple Thunderbolt Display. Just a year ago, you couldn't find a decent 4K monitor under $5,000. But Dell's only warming up: by early-2014, the computer maker plans to release a 28-inch 4K monitor priced at under $1000...