The article fails to mention the single worst feature of the PCjr -- at least the early version which was inflicted upon me.
Real IBM PCs had 15 characters worth of typeahead: if it was busy while you were typing, what you had typed was stored in a little buffer and played back later, when the next prompt arrived. If you typed too much (the 16th and subsequent chars), it would BEEP! to let you know that the extra chars were being ignored.
PCjr? Oh my.
There was still typehead on the PCjr. There was also still a beep. The semantic interaction between these, however, had been diabolically redesigned.
For some reason, the PCjr wasn't always able to receive a typed character while it was busy. Someone once claimed this was because of its lack of DMA; I never learned why. In any case, it *did* apparently have some inkling that it had lost a character.
The PCjr's somewhat more modest "bip!" therefore meant "I lost the one character you just typed".
At least that was the theory. Unfortunately, even the signal telling it that it had lost a character was flaky. What the sound actually meant was "I MIGHT have just lost a character".
Which meant that as soon as you'd typed 1-2, maybe even 3 chars, you got an audible signal meaning "give up, you have no idea what's in the input buffer now".