-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 James Richard Tyrer wrote: > Timothy Miller wrote: >> On 8/8/06, James Richard Tyrer <[EMAIL PROTECTED]> wrote: >> >>> Note that mode 1 only has 350 or 400 vertical lines in the VGA >>> emulation >>> modes and the default vertical is 70 Hz with 900 total lines. How >>> would >>> our TV out handle this? OTOH, real CGA character mode (which is >>> in the >>> IBM VGA spec) will work on a TV since it is non-interlaced with 200 >>> visible lines and 262 total lines at vertical 60 Hz . >> >> Keep in mind that we have a disconnect between what the host thinks >> VGA is doing and what we're actually scanning out of the video >> controller. The VGA emulator program converts continuously from one >> to the other. Thus, we can have any physical resolution that we want. >> For the TV, we configure the video controller appropriately and set >> up the converstion program to handle the appropriate size of the >> output framebuffer. >> >> Also, if you're wondering how to tell if there's a TV on there, you >> just don't need to. Head 0 has the analog DACs, useful for a >> multisync monitor. We'll configure that via DDC (typically). Head 1, >> IIRC, is connected to the TV chip. We'll just configure the TV >> according to the region (different BIOS images?) on head 2. Then we >> set up the two (independent) video controllers to scan out the same >> framebuffer at two different resolutions (one or both will use the INC >> instruction in the vc to skip the extra space), and viola! > > Problem! Which you missed. > > In video mode 1, (with a real VGA) the VGA output needs to be either > a 350 or 400 lines image while the TV output needs to be 200 lines. > How do we handle this? Do we have the VGA output 480 lines and the > TV output 240 lines? >
On PAL that would be (IIRC) 256 lines. Hamish. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFE2bC1/3QXwQQkZYwRAl3BAKDGl9p2xG6eJ43PVHivQ+9JWcsFFACgveSJ lfNqUwTCNLUVWduor1li7Zc= =R/vg -----END PGP SIGNATURE----- _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
