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Texas Instruments 99/4A and TMS9918 History

A little break from displays today to go back into my deep dark history. For my first 20 years in the industry, I was an I.C. designer and led led the architecture a number of CPUs and graphics devices.

I got a “shout out” of sorts in an IEEE article on the 99/4 computer by Wally Rhines, CEO of Mentor, about my work on the TMS9918 graphics unit which was my first design (started in 1977). Contrary to what the article states, I was NOT the only designer, back then it took 7 “whole engineers” (quite a few less than today) to design a graphics chip and I was the youngest person on the program. I think the 9918 took less than 1 year from raw concept to chip. Wally gave things from his perspective as a high level manager and he may be off in some details.

The 9918 coined the word “Sprites” and was used in the TI 99/4A, Colecovision, and the MSX computer in Japan. It was the first consumer chip to directly interface to DRAMs (I came up with the drive scheme). Pete Macourek and I figured out how to make the make the sprites work and then I did all the Sprite logic and control design.

A “Z80-like” register file compatible superset clone of the 9918 was used in both the Nintendo (Nintendo was a software developer for Coleco) and Sega Game systems among others.

After working on the TMS9918, I led the architecture and early logic design of the TMS9995 (which resulted in my spending 6 months in Bedford England) which is also mentioned in Wally’s article. If the TI Home Computer was not cancelled, I would have had a major part in the design of both the CPU and the Graphics chip on the 99/8 and 99/2.

Back in 1992 in the I was interviewed about the home computer in the days of BBS Bulletin Boards. This was only about 10 years after the events so they were more fresh in my mind. At the time of the 1992 interview, I was working on the first fully programmable media processor (and alluded to it in the interview) that integrated 4 DSP CPUs and a RISC processor on a single device (call the TMS320C80 or MVP). Another “little thing” that came out of that program was the Synchronous DRAM. You see I had designed the DRAM interface on the 9918 and the TMS340 graphics processor family and had worked on the Video DRAM (predecessor of today’s Graphics DRAMs) and was tired of screwing with the analog interface of DRAMs; so in a nutshell, I worked with TI’s memory group to define the first SDRAM (one of the patents can be found here). The 320C80 was the first processor to directly interface with SDRAM because it was co-designed with them.

For anyone interest, I wrote some more about my TI Home Computer and 9918 history on this blog back in the early days of this blog in 2011.

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