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The TMS9918 generates both grid-based character graphics (used to display text or background images) and [[sprite (computer graphics)|sprite]]s used for moving foreground objects.
The key features of this chip are, as highlighted
*256 by 192 full color pixels per screen
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=== TMS9918A, TMS9928A and TMS9929A ===
The '''TMS9918A''' and '''TMS9928A''' output a [[525 lines|60 Hz video signal]], while the '''TMS9929A''' outputs 50 Hz. The difference between '1' and the '2' in 'TMS9918A' and 'TMS9928A' is that the '1' version outputs [[composite video|composite]] [[NTSC]] video, while the '2' versions (including the TMS9929A) outputs analog [[YPbPr]]<ref>{{Cite web|url=https://discoverybiz.net/enu0/faq/faq_YUV_YCbCr_YPbPr.html|title=YUV, YCbCr, YPbPr colour spaces | DiscoveryBiz.Net|website=discoverybiz.net}}</ref> (Y [[luma (video)|luminance]] and Pr (R-Y) and Pb (B-Y) [[YPbPr|colour difference signals]]). The need for the latter was predominant in the [[625 lines|50 Hz world]], including Europe, due to the different video signal standards [[PAL]] and [[SECAM]]. It was more cost-effective to output Y, Pr and Pb and encode them into PAL or SECAM in the [[RF modulator]], than to try to have a different console for every different color standard. The '1' version also features an external composite video input which made it a handy chip to use in video "titlers" that could overlay text or graphics on video, while the '2' version does not.
The original variants of the TMS9918 were depletion load NMOS and manufactured on a 4.5 μm process; it was one of the first depletion load NMOS chips Texas Instruments manufactured in contrast to the [[TMS9900]] microprocessor which used the older enhancement load NMOS process that required three supply voltages. Due to the large die size and relatively high internal speed, the TMS9918 ran warm enough to necessitate a heat sink--some devices such as the Taiwanese DINA console (a hybrid Colecovision/SG-1000) neglected to install sinks and suffered from malfunctions of the chip. By 1983 Texas Instruments had shrunk the die size to 3 μm which ran cooler and no longer required a sink--MSX machines and the Sega SG-1000 used the newer 3 μm TMS9918 while most Colecovisions had the original 4.5 μm variant (the final run of the consoles produced in 1985 had the newer model TMS9918).
===TMS9118, TMS9128 and TMS9129===
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[[Toshiba]] made a [[Clone (computing)|clone]] called the '''T6950''' and does not support the undocumented pattern / color table masking feature in graphics 2 mode.<ref>{{Cite web|url=http://www.msx.org/forum/development/msx-development/undocumented-mode-1-2-polldiscussion?page=1|title=Undocumented Mode 1 + 2 : Poll/Discussion | MSX Resource Center (Page 2/4)}}</ref>{{better source needed|date=November 2015|reason=The provided source is a forum posting, which is a self-published source}} Later, Toshiba released the '''T7937A [[MSX-Engine]]''' with a built-in VDP and fixed the masking features. Both VDPs by Toshiba feature a slightly different palette than the Texas VDPs, with more vivid colors.
The TMS9918 was the basis for the [[Video display controller|VDP]] chips in Sega's [[Master System]], [[Game Gear]], and [[Mega Drive]].
==See also==
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