The Millipede Prisma 3 Graphics system was almost the ultimate TV graphics add on for use, originally with the BBC B and later, for A300 / A400 / Risc PC series computers running RISC OS 3. The system is an 8 bit RGB 768 pixel x 574 lines interlaced display which is fully broadcast genlockable. It is supplied as an external mains powered system box, with a podule control card connected by 50 way ribbon cable. The system had a 64 bit internal graphics bus for high speed graphics processing and a Hitachi HD63484P98 9.8MHz Advanced CRT controller. It has 6 MB RAM which could be used to provide up to 14 frames worth of animation.

Oh, good memory! Seems to be Steve Ciarcia's Circuit Cellar article "Build the GT180 Color Graphics Board"
https://archive.org/stream/byte-magazin ... #page/n118

I remember reading that article back then. I wonder if the chip is still available.

The NEC µPD7220, also known as the 7220, was the first true graphics processing unit (GPU), designed as a microprocessor, with VLSI, the first implemention of a graphics processor as a single Large Scale Integration (LSI) integrated circuit chip. This enabled the design of low-cost, high-performance video graphics cards, such as those from Number Nine Visual Technology, and was the basis for clones such as the Intel 82720. The 7220 project was started in 1979, and a paper was published in 1981. It debuted in Japan with NEC's PC-9800 series of personal computers in 1982, and then released independently. The 7220 had a fillrate of 1.25 megapixels per second and a rasterisation rate of 125 polygons (100-pixel by 100-pixel) per second, faster than central processing units (CPU) at the time. The 7220's high resolution color graphics led NEC to market it as a "resolution revolution". By 1983, it was used in NEC's APC computers, and other computers from Digital Equipment Corporation and Wang Laboratories.
The 7220 and its clones led the early GPU market for several years, and was still the best known GPU in 1986. It was eventually surpassed by the more powerful Hitachi HD63484 ACRTC, released in 1984.

The video memory size is 16 bit wide, so say if you want 256 colours+, up to 16bit colours,you need
16 off fast shift registers, I used 74F166's but I've seen 74F299's used as well
All explained in in Hitachi's ACRTC application note II Circuit and Software doc # ADE-502-006A.

The Deckel/Maho 'Dialog 12' CNC controller (manufactured by Grundig.)

The controller itself was a 19" box, with double extended Eurocard sized multilayer PCBs inside.
When it came out, it probably was in the same price range as a Mercedes, and not a small Mercedes.

68020 (16MHZ) for interpolation and motor control.
68020 (12MHz) plus 68881 as the main CPU.
68000 (8MHz) plus HD63484 just for graphics.
68000 (8MHz) for communication (and maybe to tie those three VME bus systems together.)
A Z8000 or similar for the PLC subsystem (maybe manufactured by Klöckner/Möller.)

Rumours said that the engineers had used Pascal for writing the code for those 68k systems.

Video of the machine:
https://www.youtube.com/watch?v=X2fUXCk6F3A

Later, there was a failed 'Dialog 13' prototype at Grundig.