Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!husc6!mit-eddie!ll-xn!ames!oliveb!pyramid!voder!apple!lsr From: lsr@apple.UUCP (Larry Rosenstein) Newsgroups: comp.sys.mac Subject: Re: Color compatibility across full Mac line Message-ID: <1209@apple.UUCP> Date: Mon, 29-Jun-87 14:56:29 EDT Article-I.D.: apple.1209 Posted: Mon Jun 29 14:56:29 1987 Date-Received: Wed, 1-Jul-87 01:47:54 EDT References: <10574@decwrl.DEC.COM> Reply-To: lsr@apple.UUCP (Larry Rosenstein) Organization: Advanced Technology Group, Apple Computer Lines: 95 In article <10574@decwrl.DEC.COM> harrow@exodus.dec.com (Jeff Harrow, NCSE BXB1-2/E02 DTN=293-5128) writes: >In response to a recent comment from Larry Rosenstein, I would >like to suggest that 20K or so of patches to continue to allow >*ALL* programs written for *ANY* Macintosh (specifically full >color programs written for the Mac II to be runable on any >Classic Mac with appropriate translation to B&W) is a VERY >reasonable tradeoff. I apologize for the confusion. The 25K figure was picked out of a hat. (That is the size of the current patches for the Mac Plus). For all I know, it could require 50K or 100K to implement the necessary code. (After thinking about it a bit longer, I think the 100K figure might be more accurate.) I don't have any concrete information on the work that went into implementing Color Quickdraw. My intuitive feel is that it was considerable. Consider what would be required. You would have to provide support for all the new data structures (colored grafPorts, patterns, cursors, windows, controls, menus; PixMaps; graphics devices; color palettes). The patches would have to understand these structures and map the colors to black or white (whichever is closer). There are probably 100+ new calls that would have to be implemented. It is not a matter of making these calls NOOPs. You need to get the same results as on a Mac II running a 1-bit deep screen, so these call have to do some amount of work. Also, some of the Color Quickdraw algorithms were written assuming a 68020. If any of these needed to be ported to the Mac Plus, they would have to be rewritten. (In this case, it is not clear that you could achieve an adequate level of performance.) On top of this, consider color printing. One would naturally want to have the same color output as on a Mac II. I think this would require most of Color Quickdraw to be ported to the Mac Plus. >One of the cornerstones of the Mac line has been this fantastic >compatibility, and it should indeed be carried forward. Will >every program written to make use of full color look decent (or >even work well) in B&W? No, of course not, but that also applies >to a Mac II running with a B&W monitor - it is up to the >developer to make sure that the result is reasonable (the gray >scales could be automatically translated to standard replacement >patterns by the patches). On a Mac II, every machine is capable of 16 levels of gray. On a Mac Plus, there is only black and white. The gray levels makes a big difference. I don't think you can simulate 16 levels of gray adequately on a Mac Plus. As far as compatibility goes, I think there are 3 kinds of color applications: (1) Applications that use the old color model. These are limited to 8 fixed colors, but this model is supported on all machines. This is a way to get limited color with no compatibility issues. (2) Applications that use the new color model, but only in a simple way. In this case, it is easy to check for the existence of a Mac II, and make different calls if color is available. The MacApp DrawShapes example does this, and I expect most commerical program will also work this way. (3) Applications that use color in a sophisticated way. Examples would be a color painting program, color animation program, a program that uses color table animation, etc. In these cases, it would be difficult to make tests at all the necessary places to support color and B&W machines. On the other hand, since they are advanced users of color, the programs would not be very useable on a B&W screen. (Consider a color painting program on a B&W screen; you would have a difficult time distinguishing colors..) >As a developer AND a user, I don't want to see the Macintosh line >in the position of so many of its competitors, where some >programs require THIS configuration, and some require THAT. I As far as color goes, the situation is not (and hopefully will never be) as bad as the MS-DOS world. The Mac II has a definite color architecture, which is extensible. I expect commercial developer to write application that fit into categories (2) or (3). In other words, either the application will either be compatible on all machines (but color machines will have extra color features), or the application will run only on color machines because it is more sophisticated. Sorry for the confusion caused by my earlier message. -- Larry Rosenstein Object Specialist Apple Computer AppleLink: Rosenstein1 UUCP: {sun, voder, nsc, mtxinu, dual}!apple!lsr CSNET: lsr@Apple.com