dhinds@portia.Stanford.EDU (David Hinds) (05/02/90)
In article <1093@ntmtv.UUCP> urbach@ntmtv.UUCP (Steve Urbach) writes: > >Go back to your math book ;^) . You forgot to includ *ALL* the variable >in your formula. 640*400 = 256k bits of MONO pixels with atributes. >To get all 256 colors you need 256K bytes just for 8 bit color >atributes plus 8k bytes for pixels and 4k bytes for intensity bit. Sorry, go back to your VGA book. Where did this memory for "pixels" come from, and what is it supposed to do? There aren't any intensity bits in graphics, either. My VGA card (an ATI VGA Wonder) didn't seem to have much trouble at 640x400 in 256 colors, with "only" 256K. >Then there is the *TEXT* mode pages that do not go away in graphics mode >with their mode bits (flash, underline,intensity, reverse) this takes >at least 3k bytes per page. Sorry, all those text pages DO go away in graphics mode; text and graphics memory are one and the same on all VGA cards I'm aware of. The 640x400/256 mode is not a standard VGA mode, and different vendors support it in different ways. The problem is fitting that 256K of memory into an address space of usually only 64K. Each card maker has their own scheme for switching pieces of memory into this address space. So, to use this mode, you either need software from your vendor, or drivers written specifically for your card. By the way - I saw an article somewhere about the final specifications of the Super VGA ROM extension. Does anyone know if any vendors have started to support this yet, or have device drivers to do this? This should clear up a lot of the problems, and make extended VGA cards vastly more useful. -David Hinds dhinds@popserver.stanford.edu
msschaa@cs.vu.nl (Schaap MS) (05/02/90)
In article <1640101@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes: >Unless you have a True Blue VGA card, it will give you 256 colors >at 640x400. It's a "standard" extension to the original IBM standard >that all independent VGA card makers allow. Read the manual to >discover what mode you have to set that card to, to get this option. >Of course your software have to support this option. No. I've got a Tseng based VGA card (VGA ULTRA) which doesn't support a higher 256 color mode with 256k than 320x200. Michael.
rb@cc.ic.ac.uk (Robin Becker) (05/03/90)
A public domain fractal program uses tweaked VGA programming to get some weird modes out of standard (register compatible) VGA cards. I have used 768 X 576 X 16 colours (221k) on my PS/2 model 80. The program is called FRACTINT and the authors include sources so you can see how they do it.
thomas@everexn.uucp (Thomas Poff) (05/05/90)
i've been told that 640 x 400 IS possible with 256k RAM on the video card. currently, i'm running a standard VGA monitor with a 512k RAM Paradise card that displays 640 x 480 w/ 256 colors (unusual). Most display cards try different sync rates for 640x480 256 color modes and thus won't work with VGA (non-multi-sink) monitors. I tho't some people might find this interesting. What I really want to know is how the heck do you get access to the other banks of 64k in the 640x480 256 color mode. I've written a TIFF file loader in Assembly that uses the 320x200 mode which uses only 64k of video RAM. could someone PLEASE tell me how to do the bank switching?!?!! Thanxs in advance.
jmerrill@jarthur.Claremont.EDU (Confusion Reigns) (05/06/90)
In article <1990May4.232402.5936@everexn.uucp> thomas@everexn.UUCP (Thomas Poff) writes: >i've been told that 640 x 400 IS possible with 256k RAM on the video card. >currently, i'm running a standard VGA monitor with a 512k RAM Paradise >card that displays 640 x 480 w/ 256 colors (unusual). Most display cards >try different sync rates for 640x480 256 color modes and thus won't work >with VGA (non-multi-sink) monitors. I tho't some people might find this >interesting. Quite, especially since I'm using a VGA monitor (non-multisync) right now, and can display 640x400x256 fine (I can't display 640x480x256 because I don't have enough RAM on my VGA card). I seriously doubt that your information is correct. Where did you hear this? -- Jason Merrill jmerrill@jarthur.claremont.edu