Path: utzoo!attcan!uunet!aplcen!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!think!mintaka!bloom-beacon!eru!luth!sunic!mcsun!ukc!inmos!braa!davidb From: davidb@braa.inmos.co.uk (David Boreham) Newsgroups: comp.os.os9 Subject: Re: RAVE Message-ID: <3956@ganymede.inmos.co.uk> Date: 6 Feb 90 10:27:31 GMT References: <12794@cbnewsd.ATT.COM> <1495@mcrware.UUCP> <12979@cbnewsd.ATT.COM> Sender: news@inmos.co.uk Reply-To: davidb@inmos.co.uk (David Boreham) Organization: none Lines: 42 In article <12979@cbnewsd.ATT.COM> knudsen@cbnewsd.ATT.COM (michael.j.knudsen) writes: >Thanks to Tim Harris for excellent answers to my RAVE questions. >Looks like CD-I will be worth the wait -- if it comes in >expandable computer boxes. > >I never heard of "CLUT" before, but it sounds like bits per pixel. >I can see that an 8-bit CLUT, one pixel per byte, would be the >easiest to program grafix algorithms for, tho heavy on memory. >(The coming KMA-68/Coco-4/CocoPro will have an 8-bit/pixel mode, >so could be easi to port RAVE to). > >Naturally using 2 or 4 bits/pixel, meaning 4 or 2 pixles/byte, >is harder to deal with in drawing lines, shifting images, etc. >Have I interpreted CLUT correctly? >-- >Mike Knudsen knudsen@ihlpl.att.com (708)-713-5134 >"Round and round the while() loop goes; > Whether it stops," Turing says, "no one knows." My company (INMOS) originally coined the acronym ``CLUT'' in 1985. It stands for Colour Look Up Table and was first used to describe the IMS~G170, then G171 devices. The IBM PS/2 computers and the 8514 display adaptor were designed around the G171 (which was specially made for IBM). Nowadays there are about 16 manufacturers of clone devices, all called ``CLUTs''. Other prople who make similar things use different names (cf RAMDAC for Brooktree). In 1989 we introduced a new video devices called the G300 CVC (Color Video Controller). This device is used in at least one of the cards designed for RAVE. Because the datasheet (and the design) was done by engineers who worked on CLUTs and because the output stage of the part is actually lifted from one of our newer CLUTs, I expect that the CLUT term crept into the G300 documentation. This may explain the use of this term in RAVE. Anyway, in INMOS, saying ``a n-bit CLUT'' would mean that the output DACs had n-bits, not that the pixels had n-bits. For instance, the G171 had 8-bit pixels but 6-bit DACS and is called a 6-bit CLUT. The G300 has 8-bit DACs and can spport either 1,2,4,8,16,24-bit pixels (in the new revision at least). David Boreham, INMOS Limited | mail(uk): davidb@inmos.co.uk or ukc!inmos!davidb Bristol, England | (us): uunet!inmos.com!davidb +44 454 616616 ex 547 | Internet: davidb@inmos.com