Where You Go From Here

What You Can Do Now

You started this primer knowing the TC-01. You now know what to check in TC-01 code before moving it to a 256. And you can use what the 256 adds:

S19 put many of them into one game.

A few things the video chip offers are not covered here:

Sprite collision coordinates. This primer reads only whether two sprites have touched. Where they touched, it works out as the assembly course does (S24): from the positions your program already keeps.
How much the blitter can do in a frame. The primer shows that a command runs on its own while your program continues, and how to tell when it has finished. It doesn't give figures for how many fills or copies fit into one frame. Measure your own: count frames around a batch of commands, as S7's counter makes easy.
The older screen modes. Graphics 1, Multicolour and the 40-column Text 1, and two display tricks: 80-column text that blinks, and pages that alternate automatically. A game has little use for them.

Put your own game on a 256. Start from S19's and change one thing at a time: a second enemy type, a level stored in the expansion RAM (S5), a title screen in Graphics 7 (S12).
Use the line interrupt in your own game. S15 held a score panel still under a scrolling playfield and changed a colour part-way down the screen. Those two handlers are the patterns to start from.
Keep the TC-01 in mind. Everything in S3 is a check you can make on your own TC-01 code. A game written with those few traps in mind is much easier to keep running on both machines. Port 26h tells it which one it's on: the TC-01 reads FFh there, and a 256 running your program reads it with bit 1 clear.

All three are worth a message.