Path: utzoo!attcan!uunet!snjsn1!bilbo!greg From: greg@bilbo (Greg Wageman) Newsgroups: sci.electronics Subject: Re: What micro in Intellivision video games? Message-ID: <987@snjsn1.SJ.ATE.SLB.COM> Date: 16 May 89 18:51:08 GMT References: <847@m3.mfci.UUCP> Sender: news@SJ.ATE.SLB.COM Reply-To: greg@sj.ate.slb.com (Greg Wageman) Organization: Schlumberger ATE, San Jose, CA Lines: 49 In article <847@m3.mfci.UUCP> colwell@mfci.UUCP (Robert Colwell) writes: > >I'm looking at an Intellivision video game for a friend, ca. 1979, which >seems to only remember how to put out vertical and horizontal sync, but >nothing else. I suspect the micro, but the manufacturer glued metal >heat sinks to the tops of the chips in question and I can't tell what >they are. Does anybody out there know? As I recall, the Intellivision used a Z80 processor driving a Texas Instruments TMS9918-A display controller. This is the same graphics chip that TI used in their 99/4 home computer, but without the proprietary "GROM" (Graphics ROM). This is a "sprite"-oriented graphics chip with several display modes, and it managed its own DRAM display memory. The highest resolution it can produce is 256 by 192 with 16 colors from a fixed palette. It generates a composite video signal on-chip. It is theoretically capable of mixing external video into its display. It is programmed via a two step, "register-select, data byte" scheme, with an auto-incrementing address mode for block-loading the display RAM. The 9918 runs quite hot so the heatsink is a good idea. I believe TI came out with a high-temp version of this part sometime later. The 9918 has a number of limitations, including the ability to display only 4 active sprites on the same scan line. Any additional active, lower-priority sprites are blanked. The result is that in some complex games, like "Donkey Kong", you will see some of the moving graphics wink out and wink back on periodically. There are also limitations in the number of simultaneous colors you can get within an 8 by 8 pixel block. All in all, it is a pain to program, but was a fairly powerful part for the price. Longish .signature follows. Skip now. Greg Wageman DOMAIN: greg@sj.ate.slb.com Schlumberger Technologies UUCP: ...!uunet!sjsca4!greg 1601 Technology Drive BIX: gwage San Jose, CA 95110-1397 CIS: 74016,352 (408) 437-5198 GEnie: G.WAGEMAN ------------------ "Live Free; Die Anyway." ------------------ Opinions expressed herein are solely the responsibility of the author.