Talk:Texas Instruments TMS9918

"RGB" output and RAM

The "2" versions do not output Red, Green, Blue video. They output Component_Video of the type where color (chroma) information for only the Red and Blue is output, and the brightness Y (luminance) signal is taken from the Green signal. Green color information is derived from the R and B color, and the Y brightness.

See YPbPr. This is sometimes seen as R-y, B-y, Y.

Computers using the component video version can be connected to a component video monitor for color, or the Y signal can be connected to a composite video monitor for greyscale.

The article also is unclear about the 16k of RAM, making it read as though the RAM is internal to the VDP. The RAM is on an external bus.

As used in the TI-99/4 and TI-99/4A computers, the 16k RAM was the VDP RAM, while the 9900 CPU had only 256 BYTES of RAM to work with. The design was such that the powerful (for the time) CPU was reduced to being a data shuffler for programs running on the VDP. Only when running pure assembly language programs, which required the 32k expansion, was the CPU brought into full use.

Dates

When (what year) was the chip released? Is it still in production and if not when was it discountinued? RJFJR (talk) 03:16, 10 December 2007 (UTC)

• As far as I know, the TMS-9918, as used in the TI-99/4 computer, was released in 1979. When the TI-99/4 became the TI-99/4A in 1981, the chip was replaced, as a result, by the TMS-9918A. It was this version of the chip that had been well-known among early computer and videogame fanatics. The TMS-9928A (NTSC) and TMS-9929A (PAL) chips, which are the ones that address the R-Y and B-Y color signals as well as luminance, were released in 1982 (the ColecoVision and its computer counterpart, the Adam, both employed the TMS-992xA series, among others). WikiPro1981X (talk) 09:08, 30 August 2009 (UTC)

Amateur's Tool

This section needs a serious revamp, or at least someone to proofread it. Salgat (talk) 01:23, 29 May 2008 (UTC)