home *** CD-ROM | disk | FTP | other *** search
- Path: sparky!uunet!haven.umd.edu!darwin.sura.net!spool.mu.edu!sdd.hp.com!caen!uwm.edu!rutgers!cbmvax!cbmehq!cbmger!peterk
- From: peterk@cbmger.de.so.commodore.com (Dr Peter Kittel Germany)
- Newsgroups: comp.sys.amiga.hardware
- Subject: Re: 4000
- Message-ID: <9589@cbmger.de.so.commodore.com>
- Date: 15 Sep 92 14:05:21 GMT
- References: <1992Sep11.201954.256@Rapnet.Sanders.Lockheed.Com> <1992Sep12.004219.1688@sbcs.sunysb.edu>
- Reply-To: peterk@cbmger.de.so.commodore.com (Dr Peter Kittel Germany)
- Organization: Commodore Germany
- Lines: 40
-
- In article <1992Sep12.004219.1688@sbcs.sunysb.edu> mrubino@csws3.ic.sunysb.edu (Michael N Rubino) writes:
- >In article <1992Sep11.201954.256@Rapnet.Sanders.Lockheed.Com> msnider@Rapnet.Sanders.Lockheed.Com (Marc A. Snider x0193) writes:
- >
- >> - standard graphic modes up to 1280x400 (more with overscan)
- >
- >Including 800x600
- >
- >> - up to 256,000 colors from a 16.8 million color palette
- >
- >The graphics are true 8bit (256 colors), but a new HAM mode gives you 256k
- >colors.
-
- Don't know who ever came up with this number of 256k colors. It's too small!
- Look, in PAL interlace, you have 1280x512 *plus* overscan. This is 640 K
- pixels. And if you choose the base colors of your HAM8 properly, you can
- have *every* color of the 24-bit palette, so you can give every pixel its
- own color. Thus I count over 640k colors and not "only" 256k :-)
-
- The issue of the base colors is the following: In HAM8, you have 6 bits
- for data and 2 bits for control. If the upper 2 bits are zero, the lower
- 6 bits select one of 64 base palette colors. And you can choose those.
- When any of the 2 control bits is set, the lower 6 bits serve to set the
- *upper 6 bits* of the selected color component (determined by the 2 bits).
- So you can't modify the lower 2 bits of a palette base color. BUT: If you
- look deeper into it, you will realize that with 64 base colors you can
- generate a set of base colors that contain every possible combination
- of the lower 2 bits of every color component (RGB, 64=4x4x4). This
- provided plus modifying the upper 6 bits freely lets you definitely
- reach *every* color of the 24-bit (8 bits each for RGB) palette!
-
- >The HAM modes now support 640x480. This gives you the 256,000 colors CBM
- >is talking about. As far as Workbench or other productivity software is
- >concerned you can only get 256 colors at 640x480.
-
- Here it is again...
-
- --
- Best regards, Dr. Peter Kittel // E-Mail to \\ Only my personal opinions...
- Commodore Frankfurt, Germany \X/ {uunet|pyramid|rutgers}!cbmvax!cbmger!peterk
- Back from vacation, anything happened?
-