Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!bruce!dec19!zik From: zik@dec19.cs.monash.edu.au (Michael Saleeba) Newsgroups: comp.arch Subject: Re: Dynamic Display Architecture Message-ID: Date: 17 Apr 91 11:41:48 GMT References: <1991Apr15.200955.3438@waikato.ac.nz> <3340@crdos1.crd.ge.COM> <20670@cbmvax.commodore.com> <1991Apr17.051746.15592@sbcs.sunysb.edu> Sender: news@bruce.cs.monash.OZ.AU Lines: 27 In <1991Apr17.051746.15592@sbcs.sunysb.edu> jallen@libserv1.ic.sunysb.edu (Joseph Allen) writes: >I had an idea for a hardware windowing circuit once which was very simple and >which would eliminate most of the problems windows have today. All you do is >break up the screen into small (maybe character sized) blocks. Then for each >block you have a pointer to where in memory the actual data is. It's really as >simple as normal character refresh memory, but with no font chip and with >wider (32-bits instead of 8) refresh memory. One device which did exactly this was the Texas Instruments TMS9929A (and others in the same family). This was a rather low-end device by today's standards (256*192 graphics), but was the graphics engine for at least two major machines, the Texas Instruments 9900 (?) and the Japanese MSX. It also had hardware sprites and some other goodies. Quite a nice system in a limited sort of way, and it certainly made eight-pixel scrolling quick as you point out. Unfortunately standard bit-scrolling was slower than ever since you had to keep track of all those pointers (actually character- generator blocks). There were some tricks to get around this, but basically it ended up slow and particularly awkard to program for, if you took advantage of all the features. ______ _ |___ / _ | | __ "I don't want the world - I just want your half." / / |_| | |/ / / / _ | / Name: Michael Saleeba / /__ | | | \ At: Monash University /_____| |_| |_|\_\ E-mail: zik@bruce.oz.au