[stella] More CC info

Subject: [stella] More CC info
From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx>
Date: Sat, 17 Aug 2002 19:11:25 -0700
I took a look at this link:


From the PIC assembly I was able to glean that the closed captioning system on line 21 works like this:

FIELD1 - shared by CC1, CC2, T1, T2
FIELD2 - shared by CC3, CC4, T3, T4

One packet of data is sent per field.

It looks like the line is split up into 14 zones that are either a white or black pixel. This doesn't bode particularly well for the 2600 since the 2600's playfield is 40 bits across, not an even multiple of 14.

It appears as though the 14 bits are interpreted as two 7-bit words. Could someone look at the assembly and try to find out more?

I believe the first 7-bit word would be interpreted as a header designating the cc mode (cc1, cc2, etc...) and the 2nd word would be the character:

Again I'm not sure whether the bits would be aligned right left or reversed but it might be clearer if someone understood the assembly better.

I haven't found any info on the header format but the character set is readily available online.

If it does turn out to be 14 bits does anyone know of a kludgy way to mix playfield and sprites to simulate scaling the 2600's display accordingly?

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