Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!gatech!bloom-beacon!husc6!sri-unix!teknowledge-vaxc!dplatt From: dplatt@teknowledge-vaxc.ARPA (Dave Platt) Newsgroups: comp.sys.mac Subject: Re: possibility of mac video board Message-ID: <14409@teknowledge-vaxc.ARPA> Date: Tue, 7-Jul-87 17:52:45 EDT Article-I.D.: teknowle.14409 Posted: Tue Jul 7 17:52:45 1987 Date-Received: Fri, 10-Jul-87 06:56:18 EDT References: <14404@teknowledge-vaxc.ARPA> Organization: Teknowledge, Inc., Palo Alto CA Lines: 40 In-reply-to: rburns@teknowledge-vaxc.ARPA's message of 7 Jul 87 20:14:34 GMT Posting-Front-End: GNU Emacs 18.41.3 of Tue Apr 7 1987 on teknowledge-vaxc (berkeley-unix) Randy Burns asks, > Is there any reason why someone couldn't create a board that would > bypass the Mac's current video circuitry so grey tones could be > displayed on the existing internal CRT? > > Correct me if I am wrong, but this shouldn't be much more complicated > than the schemes that allow a Mac Plus to use a large CRT. It might > involve replacing the existing analog board and using a clip to the > 68000 to bypass part of the Mac's video management hardware. Actually, I suspect that supporting grey-tones via the Mac's internal CRT (with an analog-board swapout) would be substantially more difficult than the "large screen" enhancements (Radius et al) that have been implemented. Reason: Color Quickdraw (or with roughly the same capabilities and interface) is needed to support screens whose pixel depth is greater than one bit. Large-screen monochrome monitors for the Plus, etc. simply extend the monochrome Quickdraw to use a larger one-bit-deep pixelmap. At the moment, CQdraw is available only in the Mac II version of the 256k ROM; it would be necessary to retrofit it into the 128k-ROM system somehow (INIT patches or a similar method) in order to support a grey-scale in the internal monitor. Apple hasn't done this, and (from what I've read in this newsgroup) they aren't seriously considering doing so due to the size of the retrofit and [I assume] their view that the market for such a retrofit would be limited. It's conceivable that one of the external-monitor vendors will decide to reverse-engineer Color Quickdraw (or license it from Apple?) in order to support a new color or grey-scale monitor that would be compatible with the SE (via the slot) or the Plus (via a clip-on interface of some sort). If this were to occur, then perhaps a hack based on this version of QD could be implemented that would use the internal monitor. Only time will tell whether there's a real market for this sort of enhancement.