Such an odd choice not to have a timer interrupt on Apple II and then having to do this kind of trickery on a MouseCard. I guess this saved a few bucks...
In its defense, it also predates a lot of what we take for granted. The idea that a game might want to scroll smoothly or update at 50/60 FPS without flickering just didn't occur to people in 1979.
Cost was the innovation for those early home computers. They weren’t doing anything remarkable, except for doing it at a price ordinary people could actually afford. If you were willing to spend more (because the computer ran your payroll, or because the computer got people to drop quarters into it all day long) you could get much more capable stuff.
These days you can drop a few hundred bucks and get something that’s not too far off from the best that money can buy. The main difference between a cheap PC and what passes for a “supercomputer” these days is that the supercomputer has much better interconnects and there’s just a lot more of it.
It's been a real trip watching the accumulation of exponential improvements the past 50 years.
Atari 800 Home Computer System was released in 1979 and had both bitmap and character graphics as well as sprites.
The Commodore 64 is _so_ much better for graphics and sound it's not even funny, but if you look at the timelines, it came along a _while_ later than the Apple II.
Woz is one of the greatest engineers of the 20th century, and the Apple II demonstrates his talent. But his brilliance at simplifying things always straddles the line between optimized and overoptimized. The Disk II might be his greatest feat at doing more with less, while the video circuitry falls just into overoptimization, given the color fringing, NTSC dependence for color, and lack of lowercase. Integer BASIC is somewhere in the middle; great performance (especially given (or maybe because) Woz knew nothing about mainstream BASIC), but the code is so tightly written that it was easier for Apple to license Microsoft BASIC than to add floating-point code to Woz's work.
Without the mouse IRQ, if one wants to support the whole line of Apple II computers, one has to vapor lock on the II+, remember that the IIgs's $C019 high bit means the inverse than the IIe, and the //c requires more trickery around it. (cf https://github.com/cc65/cc65/blob/master/libsrc/apple2/waitv...)
However, for a machine released in 1983 (the Apple IIe) it is indeed very odd. But the IIe is an odd machine in many ways.
The Apple II platform stagnated as Apple poured all their resources into the Apple III (which has all those features and much more).
The Apple II refused to die, so Apple assigned a pair of engineers to design a cost-reduced version of the Apple II, and this became the IIe. The goal was only to minimize manufacturing costs, so the new features like timers were off the table.
The IIe became an unexpected smash hit in the home and education markets (stealing those markets from the 128k Mac), and only then did Apple devote some new resources to the platform (and reposition the 128k Mac as a laughably underpowered productivity machine).
The Apple IIc (1984) was the first Apple II to get a proper modern makeover. Of course it was a flop, while the odd-ball IIe continued to fly off the shelves.
Thus there was downtime for an otherwise idle chip to do some work, and yes, saving a few dollars or 10s of dollars in 1970s money was a LOT of money!