[stella] 2600 questions

Subject: [stella] 2600 questions
From: Glenn Saunders <cybpunks@xxxxxxxxxxxxx>
Date: Tue, 20 Jun 2000 16:35:19 -0700

From the 2600 programmer's guide:

"Since the TIA latches all instructions until altered by another write operation it could be updated every 2 or 3 lines".

I'm assuming this means that whenever you want the same scanline to show up for multiple scanlines, you simply execute a WSYNC on the successive lines? But for any kernel that does register hits in mid-scanline, you must re-execute those hits on every scanline, right?

So if you just wanted to draw a stripe, you could have one line in the kernel and all others would be WSYNCs? Could the programmer also use this screentime to perform number crunching and other non-visible stuff? This is how the paddles are typically read, correct?


"when a 1 is written to D1 of the CTRLPF register, the left half of the playfield takes on the color of player 0 and the right half takes on the color of player 1."

Does this mean it actually does a color shift automatically in hardware? Also, this feature does not prevent sprites from being used on those scanlines, does it?

That's one feature I never knew about. I thought Combat was doing the color shift manually.

Also, has anyone thought of trying to wire something into the unused bits (D5 D4 and D2) of PortB/SWCHB?

Also, anyone know the reason why the trigger buttons connect to the TIA instead of PIA?

Glenn Saunders - Producer - Cyberpunks Entertainment
Personal homepage: http://www.geocities.com/Hollywood/1698
Cyberpunks Entertainment: http://cyberpunks.uni.cc

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