Dual planes and Pattern Name Table RAM

Some good progress today, a welcome change from banging my head against uncooperative SDRAM controllers.

This morning I implemented dual pattern planes, first with the MiSTer USER button selecting which plane to display, and then implementing transparency to show both.

The pattern planes were showing fixed patterns generated from the screen address. Next step was to implement Pattern Name Table (tilemap) RAM (4KB) and then display the pattern (tile) stored in the RAM. For now just Plane A, 8-bit pattern, 32x32 single page.

Pattern Name Table RAM initialised with '00'

The different number of display modes together with the 'Japlish' manual make my head spin a little. But I have no doubt after it's all implemented it'll slot together nicely - after all hardware engineers like to make life easy for themselves and to hell with the software engineers!

Now to get some pattern names into the RAM... might have to hook up the 68K soon!

[And what better way to kill time while building with Quartus than to discover new (to me) Japanese shmups on MiSTer! I'm starting to like Same!Same!Same! (aka Fire Shark).]