One of the surprises I discovered reverse engineering the NEC GB-1 EGA card was discovering that the ET2000' CRTC chip had 18 address lines. This means it can address up to 256K in a single plane.
This is more memory than ET3000 VGA chipset could handle so that was a bit odd.
I found this article from an 1986 issue of EDN magazine that shed some light.
https://archive.org/details/edn-1986_02_06/page/106/mode/2up
They talk about a theoretical board design that could do up to 1280x1024.
I think they meant four ET2002's, as four attribute controllers don't make a lot of sense as it's not like rasterizing to a CRT is a parallelable operation.
This is the first mention of the ET2003 bit-slice controller I have seen anywhere. The bit-slice engine and the ability to coordinate with a co-processor (like the Z80 on the GB-1) were clearly features targeted at producing a IBM PGC clone.
The failure of the PGC to establish itself as a standard probably scuttled all those plans, and so the ET2000 was doomed to remain only the heart of an unassuming EGA clone, with its coprocessor support relegated to doing port translation for CGA titles.
Talk about a "you pass butter" moment.
The Internet Archive is really a priceless resource. Here's a note from a 1987 issue of "Computer Magazine" about what was fixed in a 4/6/1987 ROM revision for the ET2000.
I have seen photos of boards with this date printed on their ROMs, but nobody has dumped it yet.
If you collect video cards and don't dump their ROMs and upload them there is a special place in hell for you.
There's also a mention of the ET2000's "microsequencing engine". Whatever the hell that is.
I suspect that's another part of intended PGC emulation support.
I'd like to emulate it as well someday, but that is a rabbit hole I don't dare go down for quite a while. I don't even know if my PGC runs - it doesn't fit in my 5150.
There's also the IM1024 with a 186 on it, I think.
gloriouscow
crazyc