This is a bit of history that has always fascinated me ever since I found out in the nineties while employed at Accolade, where we were reverse engineering the Sega Genesis, that the VDP in the Genesis was a variant / descendent of the humble 70's TI TMS9918 (mentioned at the heart of the SG-1000 / Colecovision / MSX and more) - we made a lot of hay in our clean room reverse engineering effort using Texas Instruments data sheets for the 9918!
It is also casually mentioned that the TMS9918 inspired the VDP in the Famicom/NES but I haven't seen any direct proof because it also seems possible that the 2A03 was derived from Nintendo/Ikegami Tsushinki 'Namco Galaxian' inspired arcade board design notably used in Donkey Kong. It's an interesting thread and perhaps studying Galaxian arcade hardware and Donkey Kong hardware and contrasting it with the TMS9918 and 2A03 can establish some geneology for home and arcade VDP design in the early 80's
But it is clear that there was a pretty 'open source' attitude towards hardware IP at SEGA and Nintendo and elswhere in the early 80s.
Nikkei Electronics did an article about the design process of the Famicom in the mid 90s. It mentions that Nintendo began work on designing the Famicom after Coleco representatives demonstrated a prototype Colecovision to them as part of an aborted Japanese distribution deal. Here's a translated version if you're interested: https://web.archive.org/web/20120731044313/http://www.glitte... The 2A03 definitely copies basic functionality ideas from the TMS9918, but it's implemented completely differently, it's not an expanded clone like the Master System VDP.
BTW after the deal with Nintendo fell through, Coleco next tried to get Sega to distribute the Colecovision. This deal also didn't happen, and the next year Sega released the nearly identical SG-1000. Kinda sad that they got screwed over twice.
Well noted, the article is a treasure! They do mention dragging a Donkey Kong with them to Ricoh and that they wanted to surpass everything before and make something that was as capable as their arcade hardware. The scrolling of the 2A03 design was a major advantage. It's very enlightening to see how they were inspired by the Colecovision but wanted to surpass it which they did in many ways.
As much as we like to consider consoles as these closed exclusive tech kind of things, a lot of it was externally designed. With Genesis/Mega Drive, if a TMS9918 gets you most of the way there and it is better than what else is out at that time, then that is good enough.
When the goal is just to put pixels on screen at the pace of the scan line, a TI part will have solved most of the nagging base issues issues and it is easy to build on. No need for a clean room design.
Yes and that would be why Sega used it in the SG-1000. TI was no longer updating the VDP so later it was evolved in the Master System which was then evolved to the Genesis/Mega Drive. So to be clear the Genesis/Mega Drive did not have a TMS9918 inside just something that was similar enough to get a foothold into reverse engineering the actual VDP.
Absolutely, I didn't think it was the TMS9918 but it had a clear lineage from it. Like getting a modern Ryzen processor and realising that old 486 instructions are in there.
It is also casually mentioned that the TMS9918 inspired the VDP in the Famicom/NES but I haven't seen any direct proof because it also seems possible that the 2A03 was derived from Nintendo/Ikegami Tsushinki 'Namco Galaxian' inspired arcade board design notably used in Donkey Kong. It's an interesting thread and perhaps studying Galaxian arcade hardware and Donkey Kong hardware and contrasting it with the TMS9918 and 2A03 can establish some geneology for home and arcade VDP design in the early 80's
But it is clear that there was a pretty 'open source' attitude towards hardware IP at SEGA and Nintendo and elswhere in the early 80s.